Frosty, sticky, robust, potent, and dank buds are in your future; all you need to do is tweak your grow environment. Environmental conditions such as temperature, humidity, C02 concentration, and ventilation/air circulation are all controllable indoors, taking Mother Nature’s whims out of the equation and providing the gardener a predictable stage to let their plants reach their full potential.
Whether you are planning your garden with a single grow tent, or are ready for a full-scale commercial grow, how you prep the space will dictate your ﬁnal yields and overall satisfaction with your grow.
The ultimate goal is to create an environment where your plants will ﬂourish and thrive with less effort from you. Controlled Environment Agriculture (CEA) or an “indoor grow” will give you the ability to control the ﬁve inputs we’ll review in this blog to cultivate happy, healthy cannabis plants with the character traits and attributes you want.
1. Grow Lights and Surface Treatments
Photosynthesis is the process that converts light into chemical energy to drive plant growth, so it’s one of the non-negotiable factors in maintaining a garden that produces results. But light can also be your enemy when growing cannabis; you need a ” lightproof ” space with no light leakage or stray light pollution from adjacent spaces or in-room equipment.
Ideally, you want a grow space that is completely dark when lights are powered down (no pilot or status lights, door frame light leaks, etc.). This allows the grower to dictate the hours of total light and total darkness. The rule of thumb for photoperiod (duration of “day”) for the vegetative phase of cannabis is >/= 18 hours of light followed by >/= four hours of darkness. When your plants are ready for ﬂowering, you’ll need equalized 12-hour light and dark periods.
Choose your lighting source using your Photosynthetic Photon Flux Density (PPFD) target or your Day Light Integral (DLI) target as your guide. Knowing how much light your plants can realistically consume involves factors like CO₂ levels and watering/nutrient schedules/concentrations. You need to select LED lighting that will hit your targets based on your environmental conditions.
Overlighting just wastes energy (jacking up energy bills) and will not produce higher yields. Fortunately, ﬁnding that sweet spot is not as hard as you think, and CABA can provide you with a free Environmental Audit to help deﬁne your space’s upper and lower lighting limits.
We also recommend you use reﬂective coatings or materials for your grow room walls to make the best out of your lighting. White walls work best for reﬂecting light, and there are many commercially available coatings you can select from.
Additionally, mating your new grow lights to a dim-to-off controller will allow for easy scheduling and consistent “days” for your plants.
Follow these lighting recommendations to create the foundation for epic growth.
2. Ventilation and Air Circulation
Your plants consume CO₂ during photosynthesis and rely on air movement to create the internal stresses required to build strong stalks and stems. Making sure that you have uniform air movement over your canopy and throughout the space will eliminate microclimates or dead zones in your garden.
There are many commercially available off-the-shelf solutions for air movers, from simple oscillating wall-mount fans to large-scale turbine fans. Determining what’s right for your garden can involve trial-and-error but is always dictated by the fan(s) locations, cubic feet per meter (CFM) measurements, and obstacles in the room that divert or disrupt airﬂow. The best practice is to observe the canopy, and if you don’t see uniform movement (think of those amber waves of grain blowing in the breeze), you need to adjust.
The other key consideration is CO₂ concentrations. If you are not supplementing CO₂, you will not need high PPFD levels on the canopy (back to lighting requirements). There is a limit to how much light a cannabis plant can utilize at atmospheric CO₂ levels. So, if you are supplementing CO₂, then your air circulation becomes even more critical as CO₂ is heavier than air and will settle low in the room if it’s not circulating adequately.
Humidity (RH) refers to the moisture content (water vapor) of the atmosphere, expressed as a percentage of the amount of moisture that can be retained by the atmosphere (moisture-holding capacity) at a given temperature and pressure without condensation. You will need just the right amount of humidity to ensure the best yields. Watering schedules, plant transpiration, temperature, and air movement all contribute to a space’s humidity.
Also, your environment’s humidity will also dictate the internal room humidity; growing in the desert versus the Paciﬁc Northwest each presents different challenges. Your space will need some dehumidiﬁcation, and some great resources out there will help you scale your needs to maintain that ideal condition for your cultivars and physical location. As a general rule, CABA recommends an RH during ﬂowering between 45-55%.
Temperature is crucial for the optimum photosynthetic activity in your garden and has some key impacts on yields, potency, and terp proﬁles (total cannabinoids). While there is no ideal temperature for a grow room, and each strain has its own happy place, maintaining a stable grow room temp between 76°F and 84°F is a good range to shoot for. Allowing for hotter “days” and cooler “nights” always provides the best results. Rely on a scheduling thermostat that you can match to your light schedule to drop a few degrees in the dark period.
In some environments, you may need to “heat” at night when the lights are off to avoid falling below an optimal room temp.
5. Nutrient Delivery
Like a man cannot live on bread alone, plants can’t survive on light and water alone. Proper nutrient levels are key to the health of your plants. If you are hand mixing and hand watering, make sure to measure your mix’s nutrient levels, pH, and electrical conductivity (EC).
Providing adequate nitrogen, potassium, and phosphorus to your garden is critical to growing those big healthy buds. Knowing your inputs and setting up the room for uniformity and consistency in larger rooms with auto feed and water systems is critical. Too often, we will take measurements at the front end of a room that are ideal, and at the “end of the line,” the NPK will be a fraction of the optimum feed.
There are different commercial nutrient blends that you can get from a local hydro store, and each brand will come with recommendations. Over time you will develop the perfect mix for your speciﬁc garden that, when applied with care and consistency, will produce a reliable yield. DON’T OVERFEED! Nitrogen toxicity is a common downfall of too many grows.
Better Control = Better Yields
Ultimately, dialing in your light, ventilation, humidity, temperature, and nutrients will set your grow up for better results, both in yield and quality. Without this attention to detail, getting the most out of your plants is challenging. Getting it right involves measuring and analyzing.
Fortunately, we have a few resources to get you started.
Check out our DLI Detective to hone in on the most efﬁcient lighting possible.
Our Environmental Audit sweetens the deal by establishing the upper and lower limits of your environment’s lighting needs.
Otherwise, email us at firstname.lastname@example.org to talk grow conditions with one of our LED lighting experts.