Cultivators in California have been hit the hardest, with a historic drought sending reservoir levels to record lows. Water rights activists in Northern California have been asking marijuana cultivators specifically to cut back on their overall usage, which some believe has contributed to the drying of steams and creeks in several counties.
In Colorado and Washington, licensed growers are preparing to lose access to federal water after the Bureau of Reclamation announced it was cutting off water rights to the industry.
Change your watering strategies:
Growers who water by hand as well as those using automated systems commonly prefer to cut their workload by watering only a few times a week, using high volumes each time.
This method creates lots of waste, however, since the cannabis plant can only absorb so much water each time. Instead of dumping several gallons on each plant every three days, cultivators who grow in soil should micro-dose the plants. The idea is to water each plant more frequently, but in greatly reduced amounts.
commonly growers water plants that are in a coco-based medium up to four times a day.
Many cultivators actually over-water their plants because they assume that water must reach the base of each plant’s roots. This is not the case – water absorption happens high up in the root systems. So growers can afford to be somewhat stingy with their watering techniques when water supplies run low.
Every grower should purchase a moisture meter and measure how much water is in the soil at depths of 6, 12 and 18 inches, once water goes below root level it is lost. Then you’re wasting water.
We caution growers to adjust their fertilizer usage accordingly when they switch to a new watering method. Taking water out of the system without also decreasing fertilizer can damage crops.
Catch & Store:
Farmers in arid climates have perfected catch-and-store methods, and the most common is a system for trapping rainwater. Growers who are serious about using rainwater should use all available roof space to catch and collect, or use tarps on their beds to trap water.
The American Rainwater Catchment Systems Association has a bevvy of literature designed to perfect catch-and-save systems on its website.
Cultivators who operate indoors should also employ a catch-and-store method that utilizes dehumidifiers. While expensive, dehumidifiers can create a zero-loss system for water, he added.
Water collected from dehumidifiers can contain organic contaminants that could be harmful for plants. While purifying this water is not a requirement, other cultivators believe in treating this water before it is used on plants.
Keep an Eye on Evaporation
Evaporation is a major enemy for water conservation and can impact crops that are watered frequently. Sometimes laying strips of carpet face-down below crops to combat evaporation and keep the ground insulated is a great idea.
Growers can also lower their light temperatures and increase the distance from light from the plants in order to slow evaporation.
Many cultivators swear by the water-saving abilities of hydroponics farming, which recirculates water to crops. Some claim that these systems can use 10 times less water than traditional field crop cultivation.
Not all of the irrigated water is used the plants, and the excess can be captured and filtered in a fine-sand tank and then recycled into the system.
Most hydroponics setups actually lose more water due to runoff and water loss in the re-filtering process. Much of the water ended up going down the drain.
Drip irrigation is still the best!