If you watch television, you’ve seen ads that urge you to do your bit to protect the environment—their theme is usually based on creating less waste and conserving valuable resources in an effort to save the planet.

Considering the state of our global economy, you might wonder why anyone would bother to incorporate ‘green’ policies into corporations whose primary goal is profitability. The truth is, though, that many environmental initiatives lead to greater profits. Simply put—if you use less, you’ll spend less.

When you look at your indoor garden space, you might see empty bottles, used growing medium, plastic pots and other waste products filling up your trash cans. You will most likely also see an array of non-disposable products: fans, pumps, trays, reservoirs, buckets, CO2 equipment, pruning shears and so on.

It’s obvious that growers are serious consumers—after all, if you want to grow a huge crop, you have to use supplies. So how do we go about conserving resources without reducing yields?

The right light for the space

One of the most common mistakes growers can make is establishing too many plants in the garden, or not using enough light for the space. This happens when an eager grower tries to fill his large space with plants while skimping on total wattage or the number of lights. If this sounds like you, it might be time to provide more lights—or reduce your garden space.

Ideal lighting coverage for a high-output indoor flowering garden:

  • 1,000 watts = four foot by four foot area, or 50 to 70 watts per square foot
  • 600 watts = three foot by three foot area, or 60 to 80 watts per square foot
  • 400 watts = two foot by two foot area, or 70 to 100 watts per square foot

Light levels higher than this are not recommended for most gardens, while lower light levels are acceptable for leafy crops such as lettuce or vegetative plants.

‘Old school’ charts might suggest you can effectively light larger areas than this with these recommended wattages, but advanced growers know that the rules for matching garden area to light have changed since these charts were written.

Many older lighting charts are based on the use of greenhouses, where you have sunlight beating down on the plants. Sure, a 1,000 watt HPS light will cover an eight foot by eight foot area in a sun-soaked greenhouse. But in your basement or closet, your grow lights are the only source of spectral radiation—the sun is taken out of the equation and your plants will require a higher level of manmade light.

I have seen uninformed growers fill an eight foot by eight foot space with plants and only use a single 1,000 watt HPS lighting system. These growers will use four times the plants, pots, soil, nutrients and water that growers using the same light to cover a four foot by four foot garden will require and guess what—the yields achieved will be roughly similar in both scenarios!

The eight foot by eight foot garden requires the reflector to be raised too high above the garden canopy in an effort to spread out the light—overall light intensity is reduced and the plants will grow in weak and scrappy. In the four foot by four foot space, though, the light can be kept at an optimal 18 inches above the canopy, allowing the plants to grow stronger and therefore more resistant to pests and disease.

As a result, yields are much higher per plant in the four foot by four foot garden. The quality is also better, as individual fruits and flowers will grow larger and heavier and be more evenly ripened. If I’m going to be harvesting five pounds of tomatoes either way, I’d certainly rather have a few large fruits than dozens of wimpy specimens! Lighting your garden using this system will increase quality while decreasing labor, cost and overall waste.

The nutrient challenge

I’m one of those perfectionist weirdos who obsesses over subtle improvements. I always want a perfect crop with big yields and high quality and I’ve been fortunate enough to meet many nutrient experts in this industry who’ve been able to help me out.

After years of side-by-side trials I now find myself using 10 to 15 products in a single batch of nutrient solution. You might think that a grower who uses this many nutrients and supplements is using too much, but I have selected products that will give my plants specific benefits, improving both quality and quantity.

Again, conservation is the key—I never overuse any single product, often using half-rate or even lower application levels. I always use a digital nutrient meter to prevent over-fertilization as well.

I have seen growers who constantly attempt to administer higher-than-recommended nutrient levels (ppm or EC) to plants in their garden. Their thinking is simple enough—if plants take in more food, they should get bigger.

Unfortunately, there is a tipping point. Plants will indeed get bigger when fed high-quality nutrients, but—just like humans—they will get sick if fed too much. While plants that are slightly underfed will only lose about 10 per cent of their total potential yield, overfed plants will be burned and their output can be reduced by as much as 50 per cent.

Keep in mind that many of the liquids and powders you administer are intended to improve flavor and aroma. If you overuse fertilizers and supplements, however, the nutrient burn will actually reduce flavor, aroma, quality and yield. Plants given appropriate amounts of high-quality inputs will always outperform overfed crops.

CO2 enrichment

It’s no secret that plants take in carbon dioxide while releasing oxygen—you probably learned that in grade school. Indoor gardeners often supplement CO2 into their garden for improved results.

What is the main source of global warming? Many experts blame CO2 emissions. If we release CO2 into our gardens, we might be contributing to melting ice at the poles. The key to using CO2 responsibly is keeping it in place—if you have a sealed garden with ideal daytime temperatures in the upper 70s, CO2 enrichment is great!

Your plants will take up as much of the valuable gas as they can and none of the emissions will leave the space. When CO2 is taken up and turned into biomass, there are no ill effects on the environment or the ozone layer—this is called sequestering and environmental scientists rely on sequestering to turn atmospheric CO2 into solid carbon (C) and gaseous oxygen (O2).

If your garden is vented (or otherwise unsealed), however, then CO2 supplementation is not the way to go. Your vent fans will pull the CO2 out of your garden along with hot air and there’s no point in supplementing carbon dioxide if your blowers are going to immediately pull the gas outside—that is just straight up air pollution.

If you want to supplement CO2, you should use a sealed garden environment. If you vent your garden, fresh air will bring in carbon dioxide and no supplementation is required.

Reusing, recycling and composting

The easiest way to reduce waste is to reuse products in our gardens. Plastic pots, net cups and fabric containers can all be washed and reused. You might be tempted to throw them away, but rinsing and reusing them is often less hassle than driving to the grow store and spending more money. Plastics that cannot be reused should be rinsed and placed into the recycling bin.

Soil and soilless mixes are easy to reuse. After harvest, remove the central root ball of each plant. Run clean water through the medium until the runoff is less than 350 ppm. Let the soil dry for a day or two. Then, soak the substrate with water and an enzyme concentrate at twice the label rate and the enzymes will break down the dead root matter. Till your mix once a day for two or three days and it will be ready for your next crop.

The money you’ll spend on enzymes is less than you would spend on new soil, and tilling is less work than bringing in heavy bags of potting mix for every cycle. This process also allows beneficial microbes to increase over time—many growers report better yields with recycled soil because of the increased microbial populations.

Organic waste such as leaves, stems and root balls should be composted. For tips on composting, check out articles from Emma Cooper, Grubbycup and other Maximum Yield contributors—they’ll tell you how to do it and how it can help with future harvests.

Look around

Are you pouring gallons of old reservoir solution down the drain? Go feed the stuff to your lawn. Do you throw away empty nutrient bottles? Recycle them.

There are plenty of ways for us to conserve resources in our gardens. Take the time to review your consumption and always look for ways to use less—you’ll save money on supplies and Mother Nature will be grateful for your efforts.