The summer months bring sunshine, happiness, escapades and mirth!  But it’s also a time of high risk!  Insects are in abundance and they want to find their way to your indoor plants! We asked our main man Zorro Torro to explain how the war on pests is won through a series of simple preventative methods. Mr Torro, the stage is all yours…

Plant pests and indoor gardens do not mix. The environmental checks and balances that are natural controls out of doors—i.e. weather and predators—are not factors indoors. The indoor garden presents a veritable Garden of Eden to the pest that gains entry. Abundant food, good weather conditions and lack of predators allow them the opportunity to enjoy their two favorite pursuits: eat or suck on plants, and reproduce. Over millions of years they have been self-selecting and are excellent at both activities.

You may remember school graphs and factoids regarding unrestricted reproduction of rabbits: an exponential increase in population could result in one year. Mites and insects have a much faster maturation cycle and produce many more eggs or young than rabbits. In just a few generations, produced in two months or less, a tiny infestation becomes a life-threatening attack on a garden.

There is no stabilization that occurs in nature: in this uneasy equilibrium, pests, plants and predators reach a balance that generates a minimal loss of crop. Indoors, however, the optimum conditions leave their population growth unchecked, bringing plants under siege.

It is for this reason that I firmly believe in a zero tolerance policy for garden pests. (I should probably practice this policy in life too, to eliminate many unnecessary disturbances.) This means that no pests are allowed in the garden. You may have read elsewhere that once your garden is infested it is impossible to eliminate pests. This is wrong. Pests can be eliminated, but it’s a far better idea to keep the growing space pest free in the first place.

Let’s say you purchased some meat that was infested with vermin. You would consider it inedible. Then why would you tolerate eating infested vegetables? Prevention is less costly than cure in material, labor, and injury to the patients—so it is wise to integrate preventative designs and practices for the garden while it is being constructed. If the garden is already in operation it should be retrofitted for prevention.

In 1668 Francesco Redi proved that spontaneous generation was a myth. By covering one jar of meat and not another he showed that maggots did not just appear; they were the result of eggs flies laid in the meat. Organisms don’t just suddenly appear. All pests found in an indoor garden originated somewhere else. Once they wend their way into the garden they find the Promised Land— free food, no species competition, no predators, and a comfortable climate.

There are only a few ways that insects can enter an indoor garden. Blocking their access is the best way to practice preventative medicine and deter plant damage.

THE EASIEST PEST IMMIGRATION ROUTES

• Piggyback a ride on humans.
• Piggyback a ride on pets.
• Ride in on outdoor garden tools.
• Arrive with un-sterile or un-pasteurized soil or planting mix.
• Immigrate with newly acquired plants or clones.
• Fly in through an unfiltered air intake pipe or an open window.
• Crawl in through cracks and holes.

PIGGYBACK A RIDE ON HUMANS

Gardeners should be careful to wear uncontaminated clothing, which can carry pests from outside into the garden.

Insects can catch a ride on humans. When we are outdoors we come in contact with nature. Grass, bushes and trees are all hosts to pests that want to colonize your garden. Mites and aphids are the most likely culprits, but small caterpillars, thrips, fungus gnats and whiteflies also use this route of entry.

All clothing that has had even casual contact with outdoor plants should be considered contaminated. Ninety-nine percent of the time this isn’t true. It is that one bad apple out of 100 that you are worried about. You step on some grass in the crack of the sidewalk and a mite hitches a ride on your footwear. You walk under a tree in the parking lot and a thrips drops on your hat or hair. A pregnant aphid catches on the fiber of your jacket.

PIGGYBACK A RIDE ON PETS

Pets are naturally curious, but should be kept out of the garden because they could be carrying a plant pest.

Pets are worse pest carriers than humans. Fur and bare feet provide good hiding places for the ride into the Promised Land. Pests use dog and cat ears, tails and bellies as handy saddles.

There is just no reason to allow a pet into the garden area. They can provide no useful service to the garden and their presence is harmful. Pets can carry an infection into the garden and transfer it by brushing up against a plant. Their fur is also a problem as it constantly shedding, along with dander particles, which then float in the air with any breeze or air circulation in the garden.

RIDE IN ON GARDEN TOOLS

Outdoor gardens are a hotbed of activity when you get down to the small level. Ants, beetles, and other creatures are scurrying about. Aphids, scale and mites are contentedly sucking plant juices. Whiteflies, gnats and leafhoppers go airborne in their pursuit of vegetation. Underground there is even more activity. Thrips and fungus gnat pupae are maturing for their above ground debut, while fungi, molds and all kinds of micro-life are playing their bit parts in the ecological cycle.

Tools should be cleaned before they are used in the indoor garden to ensure no outside pests are hitching a ride.

Just as plant pests may hitch a ride on you, they can take trips on your tools. All it takes one mite or aphid hiding on a clipper or some thrips pupae or infectious agents on a hand hoe. For this reason tools should not be returned to the indoor garden space after being taken outdoors. Only after the tool is thoroughly washed with no visible plant parts or debris may it be returned to the indoor garden.

IMMIGRATE IN SOIL OR PLANTING MIX

Most planting mixes are composed of either bark or peat moss and other ingredients such as compost, puffed minerals, sand and nutrients. The ingredients have never been in contact with plants or plant pests so they are free of contamination.

Pasteurized or sterilized soils and planting mixes are free of pests and infections. Although soil is not currently a popular medium, a high quality loam can invigorate plant growth when it is included in planting mixes. Pasteurized and sterilized soils are the only ones to use.

Importing unpasteurized planting mixes that contain soil, landscape mixes, or used soil or planting mix can be risky. They all contain a host of microorganisms that may be beneficial but they also may contain insects, their eggs, and other soil dwelling pest and disease organisms. Landscape mixes are not meant for indoor use. Outdoors, the natural balance of nature rules, so insects and other organisms are in a wavy equilibrium. Indoors, these creatures are not subject to natural controls such as weather and predators. When contaminated planting mediums are used indoors the pests they harbor will soon make themselves at home and raise large families—and you know the kids are always hungry.

New plants, even from commercial nurseries, should be quarantined before they are brought into the garden.

IMMIGRATE WITH NEWLY ACQUIRED PLANTS OR PLANTLETS

If you were a plant pest, what would be the most convenient way for you to travel? Hitch a ride on a plant that’s about to go on a journey! All plants imported into the garden should be suspected of harboring pests. Plants from hobbyist gardens, houseplants and outdoor plants are most likely to be infected. Plants from commercial nurseries are supposedly grown in sterile conditions so there is probably less chance of infection from them. Even so, they should be handled with care.

To keep your garden pest and disease free, all incoming plants should go through proper immigration procedures. First, they should be visually inspected. If they show any signs of infection the choice should be made. Are these plants so valuable that they should be disinfected? Even if no pests or infections are apparent there may be problems. For instance, mite, thrips and white fly eggs are hard to find and may be overlooked. They will hatch in three or four days and become apparent.

Using a photo loupe or magnifying glass you get a much clearer look at what’s happening close-up. Any eggs or pests become sharply defined. What were little dots become fearsome creatures with legs, crawling around, messing with your plants.

Quarantine Rules

• New plants should be kept in a totally separate garden area from any clean garden plants. The spaces should be kept as far apart as possible.
• New plants should be cared for only after other gardens are serviced.
• New plants should never be placed with other plants until they are fully certified disease-free.
• New plants should be checked daily. Both telltale marks left by the pest and the pest itself are used as indicators.

FLY IN THROUGH AN UNFILTERED AIR INTAKE PIPE OR OPEN WINDOW

I recently saw an ad for a “travel blind” vacation. You sign up for a tropical weekend and they don’t tell you where you’re going until you get there. Insects travel a lot like that. We’ve discussed how they can hitch rides on people and things. However, they can also become airborne. Swept up by the wind, they travel on air currents. It’s a risky proposition for them and many are lost to inhospitable environments where they drown, roast or starve to death. However, insect survival theory takes the losses into account. Thousands may be lost, but one successful colonization may result in hundreds of thousands or millions of progeny. It’s a risk reward ratio that has helped insects be successful for hundreds of millions of years.

Here’s where the theory literally hits the fan. Gardens are often ventilated using air from outside. On breezy days anything can be caught in a wind current. Even on calm days some pest may be flying around and get sucked into the vortex created by the air intake. The solution is simple. Place filters over all intake tubing. Not only will it protect the garden from pests, but also from dust, dander and fur. Nobody likes to see lint on his or her veggies.

I live in a part of the country that stays mild all year. During the warmest months an open window or door usually suffices to adjust the house temperature. Needless to say, my houseplants are constantly getting infected with scale, aphid and mealy bug infections. Between the breezes and the people walking in and out there’s ample opportunity for pests to get to the plants.

In a serious indoor production garden there can never be an open window. All windows must be kept shut. All air that comes in from outside, whether from under the house, through tubing in the window, or any other outside location must be filtered before it enters the room.

CRAWL IN THROUGH CRACKS AND OTHER OPENINGS

Yards are often a source of infection. Insects that hang out in host plants are only a few feet away from Paradise. If there is vegetation next to the building or house you might wish to change the landscaping. Cover the yard in used commercial carpet, installed upside down. The carpet stops all light from reaching the ground and prevents plants from reaching the light. Cover this with gravel stone or decorative mulch. With no plants growing there’s less chance of herbivore pests hanging out in the back yard. The carpet is thick enough to stop plants from growing through it, but it lets the rain soak through. It is free, and available outside any carpet store. It is convenient to use when cut into three-foot wide strips

Secure the perimeter of the indoor space. Using foam caulking, every crack and crevice should be sealed. Before sealing, place a mixture of 50% each boric acid and cinnamon in the cracks using a small spoon. Boric acid is toxic to many insects if they ingest it. When they touch it, granules stick to the exoskeleton. They lick it off and burn out, inside first. Cinnamon is toxic and repulsive to ants. When the mixture is placed in the crevices it signals to pests, “Don’t crawl here.” Make sure there are no open cracks. Even the cracks in the floors should be sealed to make it extremely difficult for insects to crawl through.

By preventing pests from gaining access to your garden, you won’t have to try to eliminate them later. The old adage proves true: an ounce of prevention is worth a pound of pesticide…

Just imagine that this super-experienced, righteous and magical dude has poked his friendly face around the corner of your indoor garden and, what’s more, he’s agreed to spend some quality time with you to get you growing like a pro. You see, Harmon was cultivating copious amounts of vegetables, fruits, flowers and herbs when Everest was no more than a spark in his daddy’s arc tube! Time to read and heed!

So pay attention, you soft and stroke-able newbie growers: here’s the Indoor Gardening Grand Wizard Harmon himself, ready to add some magic to your indoor garden!

#1 Environment is Everything

Greetings Urban Gardeners. 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.

Good luck and happy growing.

Harmon Davidson
Green Air Products