Maximum Yield USA July 2015

HUMIC OR FULVIC ACID “Fulvic acid not only surrounds mineral ions, it can also help transport them through the cell membrane and release them inside the cell.” in soils with high clay content. Clay particles and organic matter have a strong negative charge, and they tend to hold onto positively charged minerals too tightly for root hairs to easily take them up, meaning important plant nutrients such as potassium, calcium, magnesium and essential trace elements can be locked up by clay particles. Humic acid forms a bridge between the clay particles and the mineral cations. Fulvic acid has a much smaller molecular weight, and is more biologically active. Fulvic acid not only surrounds mineral ions, it can also help transport them through the cell membrane and release them inside the cell. This means fulvic acid makes a great foliar spray, allowing trace elements such as copper, iron, manganese and zinc to be better absorbed through the leaves. Fulvic acid also stimulates the metabolisms of plants, which makes fulvic acid treatments a great way to quickly correct trace metal deficiencies while stimulating plant growth. Improving Iron Uptake In soil, humic and fulvic acids help with the uptake of iron. Iron is one of the limiting factors in soil since it is easily oxidized and turned into rust. Once oxidized,100 Maximum Yield USA  |  July 2015



HUMIC OR FULVIC ACID “Fulvic acid foliar sprays make a great tonic for sick iron becomes unavailable to plants, but humic and fulvic acids not only keep iron soluble, they also stimulate cell clones, especially when membranes to take up iron more efficiently. Iron is a combined with kelp.” catalyst for chlorophyll production, so as plants take up more iron, they make more of the green pigment that harvests light energy to make sugars. Some of the sugars are used for energy to grow and reproduce, some are stored in the flowers and fruit, and some are leached from the roots to feed plant growth-promoting microbes in the root zone. Humic acid in the root zone also stimulates the uptake of nitrates and other essential elements.“Before you give up on your preciousseedlings or clones,try a little fulvic acid tonic first.”Adding Seaweed Extracts roots to initiate new growth, so a foliar spray with fulvic acid and kelp is fast-acting when absorbed by the leaves.Humic and fulvic acids work even better when combined Research shows that plants start to respond to fulvic acidswith seaweed extracts. Seaweed extracts are loaded in as little as four hours, and vigorous root growth andwith natural plant-growth hormones such as auxins stress recovery is often evident in as little as two days.and cytokinins. Humic and fulvic acids hold onto the Before you give up on your precious seedlings or clones,auxins in an exchangeable form to amplify their effects try a little fulvic acid tonic first.on plants. In fact, Virginia Tech’s 10-year study onorganic biostimulants found that five parts of humic acid Stress Protectioncombined with two parts of seaweed extracts worked 50%better than either product alone. If you want more lateral Humic and fulvic acids also help protect your plantsroot growth and more root mass, you can easily make against stress. In the Virginia Tech study, it was foundyour own humic acid and kelp root stimulant. that the 5:2 ratio of humic acid to kelp stimulated plants to make 50% more of a powerful plant protection agentPerfect for Clones called superoxide dismutase (SOD), an enzyme that sponges free radicals and protects the chloroplasts andFulvic acid foliar sprays make a great tonic for sick clones, membranes of the cell. To be effective, SOD must beespecially when combined with kelp. If your cuttings are turned on by either an iron/manganese complex or aslow to root, or if the leaves start to turn yellow and falloff, try using a fine mist of fulvic acid and seaweed at therecommended 5:2 ratio. Rooting hormones are actuallymade by plants in the leaves and transported to the102 Maximum Yield USA  |  July 2015



HUMIC OR FULVIC ACID “If you use RO water, humic copper/zinc complex. If the enzyme is activated, a single acid may be SOD molecule can perform more than 1,000 chemical reactions per second in the cell, so if you condition your a slightly plants against stress with humic acids and kelp, plants better choice.” will stay green longer and recover faster. Improved levels of SOD can help protect plants against heat stress, drought stress, UV stress and salt stress. Just remember to condition plants against stress before the stress happens. Hydroponic Use In hydroponics, both humic and fulvic acids work well, but there are minor differences. If you use RO water, humic acid may be a slightly better choice. Humic acid contains both humic and fulvic acid fractions and it has a buffering effect on pH. RO water alone has practically no buffer for pH. When using RO water, the pH can spike upwards during rapid vegetative growth, or crash during heavy fruiting and flowering—sometimes overnight. But humic and fulvic acids help buffer pH. In nature, humic and fulvic acids raise the pH of acidic soils and lower the pH of alkaline soils, neutralizing both conditions, while having a moderating effect on your plants. Humic acid also adds more than 62 beneficial trace elements to the water. Since RO water is stripped of nearly all of its minerals, humic and fulvic acids make a great water treatment for hydroponics. If you use hard water, shift the balance towards fulvic acid. Hard water is usually high in calcium and magnesium ions. Since fulvic acid molecules are smaller than humic fractions, they are better at surrounding the calcium ions to help keep them soluble and available to plants. Fulvic acid is also more acidic than most humic acid products. Since hard water is generally higher in pH, fulvic acid may be a better choice when using well water in hydroponics. “Humic and fulvic acids raise the pH of acidic soils and lower the pH of alkaline soils.”104 Maximum Yield USA  |  July 2015



HUMIC OR FULVIC ACID What’s On the Shelf? It’s not always easy to determine which products on the store shelf contain humic or fulvic acid. That’s because humic and fulvic acids are complex molecules, and regulators have a hard time defining exactly what they are. In most states, manufacturers aren’t even allowed to put the words fulvic acid on the labels. Fortunately, that may be about to change. This summer, the AAPFCO will meet in Denver to decide on formal definitions and testing procedures for humic and fulvic acids. Afterwards, the departments of agriculture in various states should be able to set new labeling standards. In the meantime, look for the words humic acid on the label and check out what color the product is. Products rich in humic acids are usually dark brown to black, and fulvic acids are usually yellow, orange or amber. “Products rich in humic acids are usually dark brown to black, and fulvic acids are usually yellow, orange or amber.” E xperiment with humic or fulvic acids to make your own custom tonics and before long, you will find the perfect recipes to grow healthier, faster-growing, more stress-resistant plants.106 Maximum Yield USA  |  July 2015



BEGINNER’S CORNER Hold That Hose!Summer Garden by Danny KlittichWatering Advice Watering is sometimes overlooked as an important Garden Design part of the gardening process. A good watering As we all know, plants schedule can improve plant growth and vigor, and take up water from a bad schedule can do the opposite. In fact, home the soil using their roots. We also know gardens are generally overwatered, which can cause that not all plants a variety of issues. Here are some tips you can use to require the same gauge your watering needs and give your plants the amount of water. In water they need on time and in the right amount. light of this fact, gardeners should108 Maximum Yield USA  |  July 2015 take these diverse watering needs into account in their garden designs. When planting, make sure the plants you are putting in the same bed or on the same sprinkler line have similar water requirements. This is why most sprinkler clocks come with many different programs so you can set each bed of plants with their own watering schedule.  

Automation ” As the seasons change, you should be adjusting yourOne of my goals as a gardener is to have watering schedule to reflect thea beautiful garden that requires minimaleffort so I can spend more time enjoying ”changing needs of your plants.it than sweating in it. Watering can be Time of Daya time-intensive practice if done by Finally, let’s touch on the time of day tohand, which is why most gardeners usesprinklers and automated timers. This water. Many of us enjoy coming home from work,also allows for consistent applicationof water. Most of us set that clock once grabbing a beverage from the fridge, and thenwhen we install it and then let it do itsthing throughout the year or growing doing some light watering in the garden to windseason, but this is not ideal. As the seasonschange, you should be adjusting your down the day. This is a nice way to relax, butwatering schedule to reflect the changingneeds of your plants. Here is a simple way watering in the evening can encourage a highto gauge the needs of your plants: overnight humidity in the garden. This makes• Water your plants deeply with a long irrigation cycle and mark it a great environment on your calendar. for plant diseases like• Shut off your irrigation and let your plants grow with that powdery mildew, rust and allotment of water.  black spot to take hold.• Wait for the plants to start to wilt.  Plant pathogens love• When you notice the first damp, humid garden signs of wilting, water your plants and then mark it on 5:30 AM conditions, as do snails your calendar. and slugs, so the best time to water is early morning• Count the days between watering and subtract by one day to get before the sun comes the ideal time between watering.  up. This allows the water Using this method, if I waterdeeply on a Monday morning and to sink into the soil andnotice on the Thursday that theplants are starting to wilt, I should set the early morning sunmy irrigation clock to water every threedays. When the weather cools, I can to dry out the gardenadjust the clock to 4-5 days, and whenit heats up, I can reduce the watering slowly. Watering in the lateschedule to every other day. This method encourages plants to grow morning may cause issuesdeep roots to take up water from lower inthe soil. When you water too frequently, in hot places because theplants will only grow roots along the toppart of the soil and then if you forget to sun may already be toowater or the temperature increases tooquickly, your plants will suffer. It also intense and the waterdecreases your water use and helps keepyour water bill low. Lastly, it prevents the on the leaves may causeground from becoming oversaturated,which causes root rot issues.  sunburn. You can also have the water come on twice, with a little time in between, to allow the moisture to soak in, reducing run-off. Watering is a seemingly simple task, but it does require some thought and effort to make your garden grow to its fullest potential. Follow these tips to ensure both healthy plants and minimal water wastage. Danny Klittich is a doctoral candidate in entomology at the University of California, Davis, and a research consultant with CleanGrow. His research focuses on increasing plant resistance and tolerance to arthropod pests. Other interests include biological control, integrated pest management and woodworking. Maximum Yield USA  |  July 2015 109

by Kyle L. Ladenburger THE ESSENTIAL ELEMENT Do you want better roots, increased flower and fruit formation, and plants that are better able to resist diseases? Make sure your plants are getting phosphorus. Here’s how.110 Maximum Yield USA  |  July 2015



PHOSPHORUSA n element is deemed essential to “PHOSPHORUS IS plant nutrition when a plant cannot ESSENTIAL FORproperly progress through its normal MAINTAININGgrowth and reproduction cycle without HEALTHY,it. Over the last century, scientists have STRONG PLANTS.”determined that 16 elements are vital toproper plant growth. If any one of these water and carbon dioxide into simpleelements is absent, a plant will not grow carbohydrates or sugars. The residualand develop to its fullest potential. energy created is then held in the ATP The essential elements are separated and distributed throughout the plantinto groups based on the roles they as needed. It is almost like charging aplay in plant development. Elements battery: the energy is harnessed, storedtermed macronutrients are most and distributed as needed.important because plants requirethem at higher amounts to perform Phosphorus Typesimportant developmental processes.Micronutrients, also called trace Plant-available phosphorus exists inelements, are usually found in most the soil solution as orthophosphatehealthy soils, but can also be supplied by anions dihydrogen phosphate anda grower via supplemental fertilization. monohydrogen phosphate. SinceAmongst the macronutrients is orthophosphates are negatively chargedphosphorus, an element with many key ions, they are not attracted by a soil’sroles to play. cation exchange capacity, but they do still interact quite strongly with iron,Phosphorus in the Garden aluminum and calcium cations in the soil, often creating products that are insolublePhosphorus encourages root formation and unavailable for plant uptake.and growth; increases flower and Phosphorus uptake is directly affectedfruit formation and the quality of by the soil or rooting media’s pH level,seed development; and enhances with maximum availability occurringdisease resistance. Phosphorus is in a pH range between 6 and 7. Plantessential for maintaining healthy, roots take up orthophosphate ionsstrong plants. It plays a crucial role when they come into contact within the production of the nucleic them in a soil solution and rootsacids DNA (deoxyribonucleic acid, with many lateral root hairs have aa molecule that encodes the genetic significantly increasedinstructions used in the development level of potential and functioning of living organisms) phosphorus uptake.and RNA (ribonucleic acid, which isused to read and interpret the DNAmap). Not only does phosphorusplay important roles in the structuraldevelopment of plants, it also has ahand in the conversion of biochemicalreactions within a plant. Most notably,it plays a role in photosynthesis andthe production of ATP, or adenosinetriphosphate-—the chemical structurethat provides the energy needed fornumerous other chemical reactions.Through photosynthesis, a plantharnesses the energy of light in thepresence of chlorophyll to combine112 Maximum Yield USA  |  July 2015

“MYCORRHIZAL FUNGI CAN HAVE A DRAMATIC EFFECT ON A PLANT’S ABILITY TO UNLOCK AND ABSORB PHOSPHORUS.” Mycorrhizal fungi can have a dramatic effect on a plant’s ability to unlock and absorb phosphorus. Cool temperatures and low moisture levels can significantly reduce the ability to absorb phosphate ions and can possibly lead to a deficiency. Phosphorus is required by plants in relatively small amounts comparedwith the other macronutrients—nitrogen andpotassium—but when levels reach a critically lowstate and deficiencies occur, plant growth is stillgreatly affected.Phosphorus DeficienciesPhosphorus deficiency can be more difficultto diagnose than nitrogen and potassiumdeficiencies because the symptoms are oftenmuch less obvious to the naked eye. Earlydetection is complicated by the fact that adeficiency may present itself in the form ofa slowly developing plant that will lookedstunted. Phosphorus-deficient plants will beslow to mature and are often mistaken for muchyounger, but healthy, plants. Some plant species,including tomatoes, corn and members of thebrassica family, will develop a purplish coloringto the stems and undersides of the leaves. Thiswill often occur in the older growth first asphosphorus is mobile within a plant, meaning itcan be transferred to developing growth, whereit is most needed. Phosphorus deficiency can result frominsufficient plant-available phosphorus in thesoil or rooting media, but can also happen dueto soil conditions that are too cold to facilitateuptake by the plant. On the other end of thescale, an excess of phosphorus may show up asa deficiency of the micronutrients iron, zinc oreven cobalt. Excessive phosphorus levels candisrupt a plant’s normal metabolism. Maximum Yield USA  |  July 2015 113

PHOSPHORUS Phosphorus Sources114 Maximum Yield USA  |  July 2015 There are both organic and inorganic sources of phosphorus. Soils high in organic matter contain higher levels of organic phosphorus from materials like plant residues, manures, composts and dead microbial tissues. Commercially sold organic phosphate fertilizers include bone meal, different varieties of composted manure, and colloidal phosphate. Inorganic phosphate fertilizers are manufactured from a material called rock phosphate that is mined and subsequently processed into products that contain a higher concentration of phosphate. These “THERE ARE products include superphosphate, mono- BOTH ORGANIC ammonium phosphate AND INORGANIC (MAP) and di-ammonium SOURCES OF phosphate (DAP). PHOSPHORUS.” Hydroponic fertilizers usually mix one of these forms with water and other elemental nutrients to create the easy-to-use, concentrated liquid fertilizers we all enjoy. When buying a phosphate fertilizer, keep in mind that plants generally require relatively less phosphorus than nitrogen and potassium, so follow directions carefully and be sure to not overdo it. Phosphorus does not readily leach from soil and has a tendency to build up over time. Outdoor soil growers may find it beneficial to have their soil tested prior to any phosphorus fertilizer application. A s a final word of caution, phosphorus and the orthophosphate anions are, for lack of a better word, touchy, and can behave differently than other elements in the soil and in a hydroponic solution. Paying careful attention to both your grow media and environmental conditions can help you get the maximum rate of return.



HYDRO FOR HE LTH: UNDERSTANDING By Dr. Lynette Morgan BIOACTIVE We all know fresh fruit COMPOUNDS and veggies are highly nutritious, but some pack a bigger punch when it comes to their health-giving, bioactive compounds. Luckily, many of these superfoods are well-suited to hydroponic systems. Read on to discover how to increase the bioactive compounds of your favorite crops. Warning: you might have to stress them out before you test them out.116 Maximum Yield USA  |  July 2015



HYDRO FOR HEALTH “ USING G rowing our own fruits and veggies gives us access to HYDROPONICS, the freshest crops possible, which is one way to ensure GROWERS ARE we get the maximum boost of both flavor and beneficial ABLE TO FULLY phytochemicals. Many of our indoor gardening favorites such as tomatoes, capsicums, strawberries, arugula and MANIPULATE watercress are natural sources of important bioactive THEIR GROWING compounds that can be increased within the plant under ENVIRONMENTS hydroponic growing conditions. Using hydroponics, growers are able to fully manipulate their growing AND NUTRIENT environments and nutrient regimens to boost certain REGIMENS plant bioactives well above those found in mass-produced TO BOOST commercial produce. So what are bioactive compounds? Bioactive compounds CERTAIN PLANT are extra nutritional compounds that occur in small BIOACTIVES.” quantities in food. They are present in addition to the fiber, carbohydrates, vitamins and minerals we118 Maximum Yield USA  |  July 2015 associate with a healthy diet, and many bioactives are still undergoing intense investigation. TYPES OF BIOACTIVE COMPOUNDS There are several types of bioactive compounds found in a wide variety of plant foods, which can be broken down into categories such as flavonoids, carotenoids, plant sterols and glucosinolates. FLAVONOIDS Flavonoids are a large group of phenolic bioactive compounds involved in a diverse range of plant processes, including UV protection, coloration and disease resistance. Flavonols are the most widespread flavonoids and are found in onions, kale, broccoli, apples, cherries, berries, tea and red wine. Flavones are similar to flavonols but are less common. They are found in parsley, thyme and celery. Capsaicin from chili peppers is a phenolic compound as are tannins found in teas and many other types of plant material. Phenolic compounds include anthocyanins, which give berries and flowers their characteristic red, blue and purple colors. CAROTENOIDS Carotenoids are well-known bioactive compounds found in commonly grown plants such as carrots, tomatoes, peas, spinach and peppers. They give fruits and vegetables their distinctive yellow, orange and red pigments. One of the most well-known carotenoids is lycopene, found in tomato skin. Others include lutein in yellow peppers and carotene in carrots.



HYDRO FOR HEALTH PLANT STEROLS Plant sterols help reduce cholesterol levels when taken “SHALLOTS in sufficient amounts. They are largely obtained from HAVE THE MOST nuts, seeds, grains and avocadoes, and nowadays are incorporated into a range of plant sterol-enriched ANTIOXIDANT margarines and spreads. ACTIVITY OF ALL THE ALLIUMS.” GLUCOSINOLATES Plants containing glucosinolates are easy to grow and “LYCOPENE, THE take up little space. Vegetables containing high levels BRIGHT RED PIGMENT of glucosinolates include broccoli, cabbage, kale, IN TOMATOES, HAS A watercress, wasabi, Brussels sprouts, arugula, salad cress, NUMBER OF POSITIVE mustard, horseradish and other cruciferous crops. These compounds, which are converted into isothiocyanates PROPERTIES, LIKE during food preparation, are continually being studied forPROTECTING HUMAN SKIN their cancer-fighting and other medicinal properties. FROM SUN DAMAGE.” SULFUR-CONTAINING COMPOUNDS Allium species such as onions, shallots, garlic and chives 120 Maximum Yield USA  |  July 2015 contain sulfur compounds that are reportedly anti- inflammatory and powerful antioxidants good for lowering cholesterol, protecting against cancers and boosting the immune system. Shallots have the most antioxidant activity of all the alliums. TOP CROPS FOR BIOACTIVE COMPOUNDS Many superfoods contain more than one category of bioactive compound and deserve more attention when it comes to hydroponic production. Apart from the brassicas, such as broccoli and watercress, and alliums, such as onions and garlic, the main hydroponic crops of interest are berry fruits, capsicums and tomatoes. BERRY FRUITS Berries contain phenolic compounds, including anthocyanins, phenolic acids, tannins, carotenoids and vitamin C, which represent a wide range of antioxidants. Berries are also said to have anti-carcinogenic and anti- inflammatory properties. They can assist with maintaining good eyesight. TOMATOES Tomatoes are a perennial favorite amongst hydroponic growers. Not only do they taste great and contain a good range of vitamins and minerals, they also contain important bioactive compounds. Of these, lycopene, the bright red pigment in tomatoes, has a number of positive properties, like protecting human skin from sun damage. It is also said to be a powerful antioxidant and an anti- carcinogen. Lycopene is fat-soluble, so to extract and absorb as much lycopene as possible, eating tomatoes with some healthy oils is recommended.

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HYDRO FOR HEALTH “MICROGREENS GENERALLY HAVE SIMILAR OR HIGHER LEVELS OF BIOACTIVE COMPOUNDS THAN THEIR MATURE VERSIONS, WHILE CAPSICUMS Capsicums, bell peppers ONLY REQUIRING A FRACTION and hot chilies are well- OF THE GROWING AREA.” suited to indoor gardens and have diverse levels of bioactive compounds, depending on their type, cultivar, growing conditions and degree of ripeness at harvest. Generally, capsicums contain good levels of carotenes, phenols, capsaicinoids, xanthophylls and flavonoids. Hot chilies contain much higher levels of the phytochemical capsaicin—a potent antioxidant—than sweet bell peppers, but bell peppers have good levels of flavonoids and phenolic acids. MICROGREENS For those with limited space, growing plants specifically for their bioactive compounds can still be achieved with microgreens. While there is a diverse range of microgreen species with equally diverse levels of different phytochemicals, those with high levels of bioactivity are red cabbage, red radish, garnet amaranth and cilantro. Overall, microgreens generally have similar or higher levels of bioactive compounds than their mature versions, while only requiring a fraction of the growing area. INCREASING BIOACTIVE COMPOUNDS Determining the growth factors that will have the greatest effect on increasing the health-giving compounds in hydroponic plants is not as simple as just providing optimal growing conditions. In fact, many of the beneficial phytochemicals in plants are produced in greater concentrations when the plants are under stress, something we usually try to avoid. For example, lycopene in tomatoes increases when tomatoes are grown hydroponically under osmotic or salt stress created with a high nutrient solution EC in the root zone. Tomato plants grown with a higher EC commonly see a 30-40% increase in lycopene concentration. If we couple this with the fact that different tomato cultivars have widely varying, naturally occurring levels of lycopene already, it is possible to grow tomato fruit with a superfood status. Lycopene is generally highest in tomato cultivars with the darkest-colored skin, which includes many of the varieties listed122 Maximum Yield USA  |  July 2015



HYDRO FOR HEALTH “LYCOPENE IS GENERALLY HIGHEST IN TOMATO124 Maximum Yield USA  |  July 2015 CULTIVARS WITH THE DARKEST- COLORED SKIN.” as black types, which have purplish skin. While some of these darker-skinned tomato types are grown commercially, there is a wide range of older, heirloom varieties that are many times higher in lycopene than the standard red, commercial, hybrid tomato fruits. By combining a tomato variety with a naturally high level of lycopene with increased nutrient EC conditions to supply a slight amount of stress, the bioactive levels in the fruits could be potentially boosted many times higher than the standard red homegrown tomato. Fortunately, commercial tomato producers have started to take advantage of the increased consumer awareness of lycopene levels and some are growing hybrids specifically bred for higher levels of this compound. These high-lycopene tomatoes are marketed and sold in mainstream grocery stores as a “functional food,” making them a potentially profitable hydroponic niche crop for greenhouse growers. Stressing plants out to increase bioactive compounds also works for hydroponically grown broccoli. Levels of phytochemicals with biological activity in broccoli are a result of both the genetics of the plant and altered environmental factors. When hydroponic broccoli plants are grown with some applied stress (increasing the EC of the nutrient with sodium chloride), levels of certain bioactive compounds increase, resulting in a healthier crop. The organosulfur compounds in onions, garlic and other alliums can also be manipulated with the use of hydroponic techniques. The concentration of organosulfur compounds in alliums is due to the large quantities of sulfur that accumulate as the plants grow. Sulfur concentrations in excess of 1% on a dry-weight basis have been reported in bulbing alliums, and much of this is partitioned into the healthy, organosulfur compounds. The concentration of these important organosulfur compounds in alliums can be increased by increasing sulfur and nitrogen fertilization. In hydroponic trials, certain organosulfur compounds increased when nitrogen levels were increased, and garlic also responds in a similar way to increasing sulfur



HYDRO FOR HEALTH and nitrogen in the nutrient solution when grown hydroponically. This not only produces healthier bulbs, “RESEARCHERS ARE MUCH but also ones with increased flavor and pungency. MORE FOCUSED ON THE Genetics also plays a major role in the overall COMPOSITIONAL QUALITY OF composition of fruits, vegetables and herbs, and this includes their levels of bioactive compounds. In the past, CERTAIN PRODUCE.” commercial varieties have largely been bred for yields, appearance and storage life. These days, researchers are much more focused on the compositional quality of certain produce, with plant-breeding programs now in effect to enhance the levels of many of the commonly known health-giving compounds such as carotenoids and anthocyanins. These new varieties will be worth trialing as they come onto the seed market. G rowing plants specifically for their bioactive compounds and health benefits may seem like a new approach to hydroponic production, but with soilless growing methods, we have the ability to fully manipulate growing conditions to induce sufficient plant stress to boost their production of these naturally occurring compounds. To maximize the bioactive compounds in crops, home gardeners and commercial growers need to consider which types of plants to grow, what the right cultivars are and the ideal conditions for increasing bioactive compounds.126 Maximum Yield USA  |  July 2015



Achieving Shear Growth: Pruning to Maximize Fruit Size by Russell Landry Do you want the maximum yields possible from your plants? Pruning your plants after pollination increases the length of time cells divide in the fruit, which means bigger fruits, as Russell Landry explains.128 Maximum Yield USA  |  July 2015

W hen we prune or top off plants, we “Forcing the plants’ vascular systems and structures are removing the fastest-growing to grow bigger signals fruits to develop bigger.”shoots. This is done to remove apicaldominance, the phenomenon where Pruning Benefits understood benefit to removing apical-the main, central stem of the plant dominant growth is increased yields.grows more strongly than the side stems. Pruning has three main benefits. The Removing apical dominance just beforeRemoving apical dominance forces the first two—controlling the direction of the fruiting buds begin to develop canremaining growth points to produce growth and encouraging vigorous new enhance yields.and grow faster. Apical dominance is growth of side shoots—are well-knowncontrolled by the production of a plant and understood. A third and lessgrowth hormone called an auxin thatis developed in the plant’s leadingshoot. Auxins, in higher concentrations,inhibit and slow the growth of sidebranches and lateral shoots, givingplants a familiar triangular, orchristmas tree, shape. Removal of this dominantshoot promotes better growththroughout the rest of the plant,resulting in new lateral shoots thatare denser and more vigorous. Thelower branches and architecture ofthe plant become stouter insteadof being restricted by the apicaldominance of the main shoot. Theresult is a plant that has a morefull-bodied vascular system. Thechannels and pathways leadinginto other parts of the plantdevelop bigger than they normallywould have become, which is whythe excessive pruning of annualfruiting plants is so successful.Forcing the plants’ vascular systemsand structures to grow biggersignals fruits to develop bigger. Maximum Yield USA  |  July 2015 129

ACHIEVING SHEAR GROWTH During growth, young fruit buds “During growth, young fruit buds demanddemand much of the plant’s resources. much of the plant’s resources.”It is thought that removing apicaldominance stimulates the development cells divide for a longer period time is than cell expansion in determiningof cell division in branches leading critical. Typically, cells within fruiting final fruit size as generally, the moreinto fruiting trusses or pedicles. These bodies will divide for a limited time cells a fruit has, the larger its finaltrusses develop larger-functioning period. Fruit development occurs in size will be.xylems and phloems that may allow four phases: During peak fruit expansion, therefor the greater importation of carbons is an intense flow of photoassimilatesfrom the leaves, potentially resulting • fruit set from mature leaves into the rapidlyin greater cell division in fruits, which • a short period of rapid cell division enlarging fruits. Sugars generatedmay translate into a greater expansion • a longer cell expansion phase by photosynthesis, along with aminopotential for the fruits. A fruit that • ripening or maturation stage acids, calcium and other nutrients,has more cells ultimately has more move via the enlarged phloem intoexpansion potential, regardless of the Research has proven it is possible the ever-enlarging fruit.size of the plant. If you are busy growing to stimulate extended periods of cell The relative strength of the plant’sleaves, you’re never going to have the transportation structure is a majornecessary cellular division to drive fruit division. This has factor for fruit enlargement. Enhancedyields to their maximum potential. been achieved by transport is dictated by cell divisions applying ethylene that have stout vascular connections.When to Prune during the early During plant growth, xylem and flowering stage, phloem enlargement occurs in anFor most fruiting annuals, it is immediately after orderly and patterned manner ofimportant that all shoot growth be pollination. The superior vascular connections.halted at the beginning stage of exact reason whyflowering and fruiting growth. This will ethylene drives I n a nutshell, to a plant, if you buildhelp ensure there is no competition for this increased rate a bigger house, the seeds inside willimmature young fruitlets. Also, helping of cell division is be afforded greater protection. For athe fruit or its truss grow and have its unknown, but one grower, this means maximum yields of the theories is and greater fruit size. One other that it may signal benefit that comes along with building a genetic trigger a bigger house is that it often takes telling the plant to longer to ripen and mature a fruit with boost cell production a robust architecture. This effect further to safeguard the seeds of the next enhances fruit size and yield, as slowing generation with a larger, protective or delaying the death of the parent envelop (the fruit). plant hinders aging and lengthens the The rate and duration of cell growth period. If you want the largest division varies among fruits and also yields possible, it is imperative to among tissues within a fruit. However, increase the length of time cells divide the cell division phase gradually shifts in the fruit after pollination. fruit into the cell expansion phase. Cell division seems to be more critical “For most fruiting annuals, it is important that all shoot growth be halted at the beginning stage of flowering and fruiting growth.”130 Maximum Yield USA  |  July 2015



as temperatures rise… don’t forget about HUMIDITY by Lacey Macri & Bob Starnes Humidity levels can sometimes get overlooked in the summer months, especially when the heat starts soaring, but after a few mishaps, most growers will begin to realize how important monitoring and controlling humidity really is. Here are some general tips for optimizing humidity indoors, and how to avoid its associated issues throughout the summer months.132 Maximum Yield USA  |  July 2015



HUMIDITY F or gardeners who grow indoors in the summer, there are a few crucial guidelines to keep in mind134 Maximum Yield USA  |  July 2015 to give plants a fighting chance against potentially hot conditions. Humidity levels are often overlooked by novice growers, but after some trial and error, most “JUST LIKE EVERY other controllable environmental condition in the growroom, there is a sweet spot for humidity levels.” growers start to realize how important monitoring and controlling humidity really is. Just like every other controllable environmental condition in the growroom, there is a sweet spot for humidity levels. Let’s start by exploring how humidity interacts with your plants throughout their natural course of development. Humidity is a lot like osmosis—plants interact with their environment to maintain an equilibrium between the water levels inside and outside of their bodies. If the relative humidity in the growroom is too low (too dry), plants will transpire more water vapor back into the environment in an attempt to stabilize humidity levels. As a result, plants may compensate for the higher-than-normal water loss by taking up more water and nutrients through their roots. This can set the stage for leaf burn if plants take up too many nutrients, or even nutrient lockout. On the flipside, if the relative humidity inside a growroom is too high, transpiration will be slowed and plants may not be able to absorb any more water or nutrients. Transpiration is controlled by the plant’s stomata, which are similar to the human lungs in the sense that there is an exchange with the environment to carry out healthy survival and development. Water vapor is released into the environment as a cooling mechanism for plants (much like sweating), and CO2 is brought back in through the stomata to encourage growth. If the relative humidity is too high, plants will struggle to make this exchange. High humidity has a choking/drowning effect on the transpiration process.



HUMIDITY High humidity “BECAUSE OF levels come with a THEIR SIZE,few other risks as well. Many flowering plants maygrowers fear molds, mildews and the absorb more waterdreaded bud rot that happens as a result than normal, whichof high humidity levels during the flowering stage can contribute toof growth. Because of their size, flowering plants may higher humidity levelsabsorb more water than normal, which can contribute to higher in the growroom.”humidity levels in the growroom, fostering a favorable environmentfor bud rot development. Keep a close eye out for signs of bud rot, andadjust your environmental controls to suit your plants’ needs, especiallyduring the final few weeks of flowering—in this case, lowering thehumidity. If you are a novice growers, be careful not to overcompensatefor these risks by lowering your humidity to dangerous levels. This canbe equally detrimental, so it’s wise to find the sweet spot tailored to yourparticular situation. There are a few easy ways to set up your growroom from the start that willlessen the chances of encountering problems associated with inadequatehumidity levels. To start, space your plants appropriately. Many growersjust starting out are under the impression that the more plants they grow,the greater yields they will get. However, overcrowding plants predisposesthe environment to high humidity levels, especially since most plantsmaintain a humidity rating of close to 100%. As a general rule, give eachplant at least a 2- by 2-ft. area to flourish. Another added bonus to136 Maximum Yield USA  |  July 2015



HUMIDITY“OVERCROWDING spacing yourPLANTS PREDISPOSES plants generouslythe environment to is it opens up the benefitshigh humidity levels, of pinching plants. Growers whoespecially since most overcrowd their tents also have to beplants maintain a careful, as an overly dense population of growthhumidity rating of may promote even higher humidity levels. Deep waterclose to 100%.” culture may be particularly useful to accommodate these standards, as the nature of the set-up allows for robust root growth, along with maximizing vertical growth and providing a strong foundation to support prolific horizontal growth when spaced appropriately. Oscillating fans are another no-brainer when it comes to stabilizing humidity levels in your growroom. While they may not be enough to deter all of the problems associated with excess humidity, they will improve air movement, which vastly contributes to healthy transpiration. Determining the equipment you need to deal with humidity depends on the region where you’re growing. If you live in a humid climate, additional fans, dehumidifiers and exhaust systems may be necessary. In areas where arid climates are prolific, you might need a humidifier. D etermining your target humidity level based on your region’s climate and the garden’s stage of growth is vital for maximizing growth potential. Once you do these two things, you can determine what type of equipment you need to maintain your targets. You can implement all of the tricks in the world, but having your humidity out of whack will likely negate all of your other efforts, wasting precious time and money.138 Maximum Yield USA  |  July 2015



Good Greenhouse by Frank Rauscher | A greenhouse can provide growers of all skill levels with some fantastic, additional growing space. With the proper design, greenhouses can give green thumbs extended growing seasons and reduce their electrical expenses and dependency on artificial lighting. A greenhouse can be one of basic utility, or one that combines utility with beauty. It’s all up to you, your budget and your imagination. This article is for anyone considering the construction of their first greenhouse.140 Maximum Yield USA  |  July 2015



GOOD GREENHOUSE PLANNING and be aware of any build-T here are many reasons greenhouses ing restrictions are so popular. They are great for in your area ifproviding optimal growing conditions you’re setting upwhile helping growers reduce the something huge.electrical costs of growing purely You do not wantindoors. Need some additional, to be requiredsheltered space to grow the crops you to change planswant? Start planning a greenhouse! mid-stream.The joy that comes with having awonderful room filled with thriving Size &plants will be worth the effort of Locationdesigning and building a greenhouseon your property. Of course, if you To beginare already growing outdoors, thebenefits of protecting your plants from planning yourtemperature swings, pests and wind-blown diseases by adding a greenhouse greenhouse,to the mix can’t be overlooked. When you plan your new green- look at thehouse, most pre-fab kits from thehardware store do not come with area you have Fitting your greenhouse into your available space is key.extras like benches, tables, automaticvents, foundations or heating equip- to work with.ment. This is where proper planningcomes in. You will also need a source Greenhouses can be bought or built in mind you are not confined to squareof water, and perhaps electricity, soplan around these requirements, in many shapes, with many different or rectangular dimensions. You can features to better fit into your available have an L-shaped greenhouse, or even space. When choosing a location for separate mini greenhouses, which may your greenhouse, consider how much help you maximize your floor plan. space you’ll need for aisles, preparation Picture where the entry makes the most areas and equipment storage. Sketch sense, and how big it will be. Will you out some possible dimensions, keeping need to add a pathway leading up to142 Maximum Yield USA  |  July 2015



GOOD GREENHOUSE PLANNING the greenhouse? Decide if you want to move the greenhouse over time. Whether it’s a permanent or a portable structure, each option will heavily influence the size of your greenhouse and the materials you will end up needing. Lastly, if a part of your greenhouse is against a wall, keep in mind that one side of the greenhouse will not receive as much sunshine, so you’ll need to plan around this. Budget The next thing to look at is your budget. Decide what you are comfortable spending before you start planning all of your greenhouse’s features. From simple hoop types, to elaborate wood, metal and glass structures with many features, the cost per square foot of a greenhouse can vary enormously. Do you intend to grow during colder weather? If so, you will likely need to provide better insulation and even a heat source for your plants. Will you be combining natural solar energy with artificial light to provide the light energy needed by some of the crops you’ll grow? If so, planning where and how much artificial light is vital at the early stages of your design.144 Maximum Yield USA  |  July 2015

Greenhouse options vary depending on budget and needs. Next, it’s time to make a checklist of all of your desiredfeatures and compare this to your budget. Refer to thischecklist throughout the design process. Leaving animportant feature out only to discover it’s missing nearthe end of the design process will only be disappointing.“FROM SIMPLE HOOP TYPES, TOELABORATE WOOD, METAL AND GLASSSTRUCTURES WITH MANY FEATURES,THE COST PER SQUARE FOOT OF A GREENHOUSE CAN VARY ENORMOUSLY.” Maximum Yield USA  |  July 2015 145

GOOD GREENHOUSE PLANNING “ EACH DOOR TO THE OUTSIDE OF YOUR GREENHOUSE REDUCES BENCH SPACE AND, ULTIMATELY, THE NUMBER OF PLANTS YOU CAN GROW.”Wire mesh shelves are a common choice.Aisles Tables & Benches point but can take up a lot of space or reduce the amount of direct sunshineYou will need aisles in your green- Plan your tables and benches to coin- entering the greenhouse due to theirhouse to access your plants. Aisles are cide with your aisles. Start by looking design or construction. Barrels, formost efficient when they are down the at the many different types of benches instance, might be used to supportmiddle, so you can reach your plants or tables available and understanding tables or benches, but they take up afrom every angle. If your aisles do not the benefits of each. Keep in mind you lot of space. When considering the typeallow you to easily reach everywhere need to provide space and access to of table or bench to construct, look atyou are growing, it is likely to become water your plants. You also need space every aspect you can imagine, not justan issue down the road. If you will be to wash your hands, tools and other the immediate cost. Encourage yourselfusing a wheelbarrow, wagon or nurs- materials. As these work areas are not to revisit these plans before committingery trailer, make sure the aisles can actually providing space for plants, con- to your final design.accommodate it. Another important sider multi-functional tables. You don’tfactor in deciding the size of your aisles necessarily need a sink that drains tois the basic designs of the walls. Are wash your hands or tools, just some-your aisles far enough away from the thing to catch the water.walls so occupants can walk upright? Are you going to put plants beneathFor example, a barn-style greenhouse the work table? If so, the type ofallows you to reach hanging baskets, materials used for the table needsas they are slightly closer to you, while to keep debris from falling onto theallowing for easier construction and a plants below. Being able to keep yourstronger structure, but will influence new greenhouse clean and organizedwhere your aisles run. will maximize production. If your To complete the plan for your aisles, tables or benches will be shadingdecide if you can make your green- some of the plants beneath them,house work with a single entry point. you will need to grow plants thatEach door to the outside of your require less direct sunlight there, orgreenhouse reduces bench space and, provide artificial light for them.ultimately, the number of plants you The size and materials used for yourcan grow. The added cost for additional benches is critical. Some economicaldoors is another thing to consider. benches or tables come at a good price146 Maximum Yield USA  |  July 2015



GOOD GREENHOUSE PLANNINGFlexibility height-adjusted, adding to the design’s flexibility—just make sure that above all else, they are sturdy. You can also use growAs time goes by, you may wish to change the size or racks on wheels that are not only height-adjustable, but haveheight of your containers as your plants mature or the right kind of flooring to be moved to different areas ofyou add more variety to the mix. Is your watering the greenhouse, making access to plants that much better.system able to accommodate these changes? If you’re Your top-tier plants can be grown in hanging pots suspendedusing artificial lights, can they be moved or adjusted? from a horizontal pole to help reduce construction costsFlexibility is an important part of a well-designed while maximizing the amount of space and sunshine avail-greenhouse. Some shelf and bench varieties can be able for your crops. Making the best use of sunshine should be kept in mind throughout the design process. Shaded plants do not produce maximum yields. Framing & Siding Consider the types of siding and framing materials you will use after you’ve made your decisions regarding benches, tables, hanging poles, aisles and entryways, as all of these elements can impact the siding you’ll need. Siding choices include glass, fiberglass, plastics and more. Framing choices include wood, aluminum, galvanized steel, PVC plastic and more. Research the benefits and pitfalls of each material before making a decision. Your local climate will matter here a great deal. Is it sweltering hot in the summer? Freezing cold in the winter? Do your plants need protection from wind and snow? The strength of the siding and framing materials plays a huge role in the durability of your greenhouse. “ YOU WILL LIKELY NEED SOME HEATING AND VENTILATION OR COOLING EQUIPMENT WITHIN YOUR GREENHOUSE.”148 Maximum Yield USA  |  July 2015