1 Environment is Everything
Greetings stoners/growers. Did you know that some new indoor gardeners think that all they need to do is buy a grow light and hang it above their plants? WRONG! These growers are underestimating the importance of environmental quality. Just like people, plants can only perform well when they are comfortable and receiving proper atmospheric conditions. Maintaining a proper temperature and humidity range is really critical to your success. Many plants enjoy higher relative humidity (60-80%) in their vegetative stage and lower (40-50%) during flowering. I try to maintain my indoor garden at 82°F (28°C) when the lights are on and 64°F (18°C) when they are off – but hey, that’s just me and my capsicums. Different plants have different requirements.
Equally important is clean air, proper CO2 / oxygen ratio, and adequate air circulation. You wouldn’t want to spend your life locked in a stagnant cupboard, would you? Air movement is your best defense against mold and other pathogens as well as the plants’ vehicle to remove waste products from the leaves and facilitate respiration. There is something magical about fresh air so don’t underestimate the importance of it. Fresh air brings fresh supplies of CO2 – a crucial component of photosynthesis – your plants can’t “breathe” without it! You can bring fresh air in with an intake port, exhaust fan and timer. Another way to ensure a constant supply of fresh air is to provide a convection air leak in the enclosure. Furnish a small hole near the floor at one end and another in the ceiling at the other end. Use some kind of filter to catch bugs and dirt. (At the very least a window screen or a pair of old tights if you have any spares knocking around!) For optimum control of temperature and humidity and coordination of CO2 enrichment and ventilation, specialized environmental controls are available to automate and maintain precise atmospheric conditions.
#2 Killing with Kindness
As your plants grow, their nutrient requirements increase, so it’s all too easy to get over-excited when they are young and err into over indulgence with fertilizers, plant additives, enhancers, and other stuff. Sometimes it’s because of the old adage, “If a little is good, more must be better,” or you just follow too many people’s advice. Before you know it, you’ve got some kind of mysterious blend of chemical hocus-pocus that may not be compatible.
When you see curled leaves like claws, burnt leaf tips, slow overall growth or damaged new growth (terminal shoots), my advice is usually “go back to basics.” Flush the media with clean, pure water for a day or two, and then run a half strength dose of a good quality fertilizer. Once the plants re-establish themselves and begin to show normal growth, slowly increase the nutrient concentration and eventually you can start adding other growth enhancing products again.
A reasonable amount of additives can be very advantageous. My advice is to choose a well-established manufacturer who provides a complete line of nutrients and additives, and follow their program. Always use a conductivity meter to check the strength of your nutrient solution.
#3 Watering and Transplanting
Many new growers start with hand-watering their plants in soil and pots. It seems to be the simplest way but improper watering and transplanting is a common error. Start off your plants in small pots and make sure you transplant your plants in graduations. Let the plants develop a solid root ball before increasing container size, and then only step up a couple inches at a time. The theory here is to keep a consistent medium that the roots can dominate. Empty soil stays too wet and becomes water logged. The plant needs to generate a thick root ball mass to be healthy. Use a good quality soil mix that is light and provides good air retention. Pack the soil firmly and water immediately. Leave soil a few inches below the top of the container to hold water while it soaks in during watering. Do not water too often. It’s good to let the media dry out a little and then water completely. Feel the weight of the pot – it’s a great indicator of how much water is in the soil. Water lightly once to wet the substrate and break the soil tension, then come back after a minute and saturate. Let some water run out the bottom to leach out old contaminants. If you use trays under your pots, do not leave standing water. Kick the bucket, or lift it a bit to judge weight. This is a good indicator of water content. Too-frequent watering and over fertilizing is one of the most common mistakes new growers make. An old saying for soil growing is “fertilize weakly weekly,” and there is some truth to that.
#4 Understanding pH
Besides just the addition of fertilizer, nutrient solutions require other specific properties to work effectively. pH is an important factor. This ranges between 5 and 7 in most cases but varies depending on a gamut of particulars: cultivar, plant growth stage, type of grow system, fertilizer program, water characteristics, and even environmental conditions (light, heat, etc.) to name a few. My advice to growers is to let the pH run a range of about a full point. For typical plants, the rule of thumb is to aim for or 6.0 and let it rise (or drop as the case may be) about a point before adding adjusters. Essential elements become available at different pH values, so by letting your pH vary across the scale you have a better chance of all elements finding their optimum assimilation point. I prefer the range of 5.5 to 6.5 as a good gradient zone. Letting the pH drift alkaline (above 7.0) is more likely to stress plants than a slightly acidic pH. My main point here is that you don’t need to adjust your pH as often as you might be led to believe. Invest in a quality, digital pH meter and calibrate it regularly. Finally, only measure the pH of your nutrient solution once you have added all your fertilizer and additives, as these can affect it too.
#5 Nutrient Temperature
Root health is vital to your garden’s success so naturally you don’t want to cook your roots or allow them to become too cold. Nutrients are most easily absorbed when the nutrient solution is around 68°F (20°C). Typically, temperatures in your indoor garden will drop at night as much as 10°F (5°C). That is perfectly acceptable. But if your water / nutrient solution is too cool it will cause the growth rate to decrease. Cold tap water can shock roots and cause other problems. However if the solution is too hot all kind of nasty things will happen. As water becomes warmer it can hold decreasing amounts of dissolved oxygen (which is really important for root health). If you are using a recirculating system, pay special attention to heat as it can transfer to the solution in many ways. The most common is absorption from trays, channels, containers or plumbing. This is a result of radiant heat from sunlight or even artificial lighting. Pumps can also create heat and be a factor. Protect your solution from direct sunlight. Insulate or sink your nutrient reservoir in the ground if possible. I have run my solutions through buried hose or pipe to cool them before returning to the system. Water chillers are available for extremely warm conditions. Nutrient heaters (with integrated thermostats) are also available at very reasonable prices to help you cope with cold conditions.
#6 Oxygen
Oxygen content in your nutrient solution is often neglected or misunderstood. Just like fish require oxygen in water, so do plants. Plant roots absorb O2 and need it for various purposes, but the primary reason for keeping an oxygenated solution is to fend off anaerobic bacteria such as Phytophthora root rot (blight) and damping off fungus (Rhizoctonia root rot). For the same reason, soil and other grow mediums must offer good aeration. As I said above, solutions can become depleted of oxygen if the water becomes too warm or stagnant. Organic solutions can easily become deficient as the culture often utilizes the oxygen. Dissolved oxygen is measured in mg/L. Typical optimum values range about 10 and 30 mg/L. Over 40 is considered saturated and under 5 is considered deficient. There are reagent kits and meters available but I hardly find them necessary. Air stones or spray nozzles generally do the trick. I often use a hose-end siphoning device designed for proportioning liquids into a hose stream and just let the intake suck air. It will induce fine bubbles into your water flow. They are cheap and widely available in garden shops. Soils should contain good porous substrates and, again, be sure to let them dry out between watering. Finally, keep your nutrient solutions agitated to prevent stagnation.
#7 Lighting
You could write a whole book on lighting an indoor garden so I’ll just try and outline some basic principles here. Where you place your lights can dramatically influence plant growth rate and structure. If the light levels are insufficient, plants will respond slowly and tend to be weak and elongated. It will be fairly obvious; you need more light. If the lights are too close to the plants the new growth will dry and curl. This will also be pretty apparent and is a more common mistake. Place your hand at the same level as the tops of your plants. Keep it there for a minute or so. If your hand starts to become noticeably warm your lights may be too close. Another good way to measure temperature is to fill a small plastic bottle with water and hang it at plant level with a mercury thermometer in it. This will provide an accurate interpretation of actual temperature. Most of the heat accumulation in an enclosure is from the lights. Air and water-cooled fixtures are a very effective method to remove unwanted heat before it becomes an atmospheric concern.
#8 Know Your Limits
Many plants have a vegetative stage and a flowering stage. Basically, the vegetative stage is when the plant builds its structure – the botanical ‘scaffolding’ to support the future harvest. The flowering stage is when the plant stops growing and focuses its energies on producing flowers and fruit.
What makes a plant flower? Many things can trigger it, depending on the plant type. For instance, I delay my capsicums from producing fruit by physically picking off the flowers. I do this so that they first grow to a decent size before concentrating on producing a bigger harvest for me!
Plants like Poinsettia and Kalanchoe require short day lengths in order to start flowering (usually 11 hours or less). In an indoor garden, you can control when these plants grow and flower just by changing the length of your lights-on period. If you’re growing plants like these (known as ‘photosensitive’ plants) it’s important to ensure that they enjoy complete darkness during the lights off period – so no peaking! They require uninterrupted darkness in order to properly trigger flowering.
I’m wary of opening up a can of worms here but consider the following simple advice: When growing plants indoors, it’s important to take the space you have available into account. Sounds like commonsense, huh? But listen! It’s all too easy to get carried away in the vegetative stage, thinking that the bigger you grow your plants, they will automatically carry more fruit. This is true to an extent but you have to match the size of your plants to the containers they are grown in, the space available in your indoor garden, and the amount of light available. Also, remember that the transition from vegetative into flowering can be fairly gradual (it doesn’t happen overnight!) so growth can continue for a while even after you induce flowering with shortened days / lengthened nights. Knowing when to induce your plants to flower is a fine art (or science, depending on how you look at it!). Novice growers invariably grow their plants way, way too big at first.
#9 Don’t Get Bugged Out
Keep your indoor garden clean. Don’t get lazy: otherwise insects and diseases will be on you before you know it! Insect and disease control is one of the most devastating and misunderstood hazards of hobby growers. You get bugs, or at least finally notice them, and at that point it is often too late. You spray for them any number of lethal or ineffective insecticides, and that seems to help, but it takes a toll on your plants, and then the bugs come back. It is frustrating and it can cost you your yields and all the time and money you have invested in your garden. Plant diseases are much the same story. But there is a rhyme and reason to this dilemma. You just need to learn the timing and lifecycles of these ailments. You need to be proactive. Take precautionary steps. Beat them to the punch. There are many methods to avoid infestation, both procedural and environmental.
Clean the grow area and all plant equipment and systems between crops. Use 10% sodium hypochlorite (household bleach) or 3% hydrogen peroxide or whatever your desired disinfectant might be. Clean and rinse well. This is the best way to avoid common plant disease. Use filters to keep outside bugs and spores out.
Healthy plants are reasonably capable of fending off disease by their own mechanisms, whereas stressed plants become susceptible to all pests and disease. Bugs and disease usually start on one plant. Closely inspect all plants frequently, especially ones which seem to be weak or ailing. Learn where they hide and the telltale signs of damage. If you find a bug, act quick to reference information on the remedy. Bugs (and disease) have very definite life cycles. Don’t just spray, do your research. You have to know what, when, and how often to administer treatment. There will be a pattern of applications necessary to stop the infestation. This is the key. Believe me. You’ve got to be smarter than the bug (and that takes some effort!), but you will thank yourself many times over if you learn the fundamentals of proper insect management. Otherwise forget it. You might as well give up now and save yourself all the frustration of failure. Once you have a clean garden you might look into the application of predatory bugs, however this takes a wholly different level of skill and knowledge. There is so much more I want to tell you about this subject but … they don’t pay me enough for that. Heheh.
#10 Be Observant!
One of the most common mistakes, if you can call it that, is just not paying attention. You need to spend time just looking closely at your plants. Get your nose dirty. Become one with them. You can actually learn to feel what they feel. And in doing so, you can share in their triumph and trauma. Don’t be afraid to touch the plant. They like it. A healthy plant is not frail. Feel its structure and feel its life force. Look closely at your stem and sun leaves. Look for bugs or mold, injuries or deformities. Look under the leaves and on top and in the internodes. Look everyday at the new growth, the apical meristems and terminal shoots. Look for dry or curled tips, chlorosis or darkening of the stems. They should be growing constantly and look lush and bright green. Rejoice in the splendor of the tiny new leaves unfolding. Use a magnifying glass or microscope at times. Get into it. There is a lot to be learned and gained by simply being observant.
