Gardening is, without a doubt, one of the simplest and greatest pleasures in my life. Most of the time, that is. I have seen my share of failures and made more than my share of mistakes.
Each time we start a new garden we begin with a picture in our mind of a successful outcome. For cannabis gardeners that picture is usually of a bountiful harvest of beautiful, fragrant and potent flowers that will supply ourselves and those we share with. As anyone who has taken up growing their own will tell you, it doesn’t always work out that way.
While marijuana is often referred to as a weed and it certainly can grow like one, it is not an easy crop to grow well. There are a number of common failures to growing the herb that can seriously compromise your results. Some of these failures are quite final and will simply kill your plants and force you to begin again.
My goal in writing this article is to draw your attention to the most common sources of failure and to help you steer clear of these potential problems. If you following these 5 Simple Rules in your first attempt, your chances of harvesting a quality crop are greatly improved.
Let’s get started. Here they are:
- Plan the timing of your garden.
Cannabis grown from seed indoors is, on average, a 120 day crop. A typical growth schedule might be 4 weeks from seed to first transplant, 4 weeks vegetative growth, then add 9 weeks to bloom and finish. That is 17 weeks, or just over 4 months.
There are people that will argue that they can finish a plant in less time and I have seen it done. But time is what it takes to make high quality flowers, so don’t rush yourself or your plants.
Also be aware of the months you’ve allocated to your garden and compare that to your personal calendar. Nothing is worse than getting 3 months into a grow and then remembering that you are supposed to travel for vacation just as your plants are beginning to bloom. Indoor gardens that are abandoned for weeks at a time frequently fail.
- Start with clean, well draining growing media.
The science of horticulture is constantly improving as are the materials used to grow crops indoors. In the past the commercial greenhouse and nursery industry used to grow their crops in clay pots and field soils.
The practice of using soils indoors has been replaced almost entirely by the use of sterile packaged growing media. The primary reason for this is to reduce the numbers of pests and pathogens that are introduced to the greenhouse.
Simply put, soil carries bugs and their larvae along with a whole raft of molds and spores. These pests, once introduced, are tough to fight and can be disastrous for your indoor garden. If the word ‘soil’ is on the label, don’t bring it indoors.
Packaged media comes in many forms. My personal preference is for Peat-Lite mixes which are comprised largely of peat moss amended with perlite, vermiculite or both.
A good usable peat-lite mix for cannabis would contain in the neighborhood of 60-65% peat. This makes for a medium weight mix that has good moisture holding capability, yet drains well.
- Use a complete fertilizer that is appropriate for your water type
Most packaged fertilizers carry on the label a guaranteed analysis of the elements inside. The most important of these are the N-P-K levels. N-P-K stands for nitrogen, phosphorus and potassium, the three macro elements that plants need to grow.
In addition to these macro elements are a group of lower concentration elements referred to as micro elements. These include calcium and magnesium, and in smaller amounts iron, copper, boron, manganese, molybdenum and zinc.
A complete fertilizer will contain all of these elements in ratios that are appropriate for growing plants. There are formulations made for growing fruits and vegetables that closely match the requirements of marijuana. These are absolutely fine for your garden.
In many parts of Colorado, home gardeners are using city or municipal water sources. Municipal water is treated to lower the calcium and magnesium content and to remove trace elements like iron.
This treatment makes the water taste better and makes it more useful for things like bathing and laundering clothes. Unfortunately for gardeners this means that there is less of these essential elements to feed the plants.
If you are on municipal water that is low in calcium and magnesium you will need to supply these to your plants via your fertilizer choices.
- Provide adequate light
The single greatest limiting factor in indoor cannabis growing is light. The most common types of artificial light used indoors to grow this crop are fluorescent and high-pressure sodium / metal halide bulbs. Both work well and can be used at all stages of growth. Both have their merits and their drawbacks. On/off time is controlled with a simple timer.
The most commonly used type of fluorescent lighting used in indoor gardens are high-output T5 bulbs. These usually come in 4 ft lengths, although 2 ft bulbs are available. The fixtures are made up of multiple tubes. Common configurations are 4-tube and 8-tube panels that can be easily hung over the plants.
T5 fluorescent lighting is highly diffused which makes it easy on the eyes. The bulbs run very cool making them the go-to choice when managing high temperatures indoors is a concern. They produce a very high quality light and can be used to grow your plants from start to finish.
High-pressure sodium and metal halide bulbs have a much higher output from a much smaller fixture. HPS/halide lights burn hot and produce huge amounts of heat energy. This all adds up to make them a more productive lighting source for indoor gardeners. Having said that, the heat energy, while easy to manage in the winter months, can be an expensive factor to try and control in the summer months.
All things being equal, my preference is to run HPS during the cold months and fluorescent bulbs in the summer. Taller plants will benefit from the extra punch of the HPS/halide bulbs in that the light will reach and be more effective in the lower half of the plant. Fluorescent bulbs have less power and therefore will tend to under light the lower branches of taller plants.
- Control your environment
Controlling your environment means keeping your grow area clean and clear of pests. This means removing any dead or diseased leaves from the plants, from the media and from the surrounding floors.
You must also control your ambient temperatures. Marijuana plants do very well in the 60 – 75 F range. Run your garden colder and you run the risk of slow growth and mildew/mold outbreaks. Maintaining temps higher than 80 and you invite pests like mites into your garden.
Colorado’s humidity can swing wildly from season to season. Generally you want to keep your indoor garden air moist, but not too moist. A reasonable working range is between 40 and 60% relative humidity.
It would be impossible to cover every potential problem in a single article. By paying attention to these 5 factors you will have eliminated much of the risk of failure facing first time indoor marijuana gardeners.
I have spent a good deal of time learning how to grow this plant successfully indoors. I hope you find this information useful. If so, drop me a note and introduce yourself or stop by my shop in Lafayette. One can never have too many gardener friends.