Cannabis plants are roughly 90 percent water. They transport water through their circulatory system to turn sunlight (photosynthesis) and carbon dioxide (transpiration) into food. Water also helps transport nutrients to the plant and, providing the pH level is sufficient, will help those nutrients absorb into the root system. Needless to say, water is pretty important to a cannabis plant’s health. But, there can be too much of a good thing. Many novice growers tend to overwater their plants in hopes of speeding the growth process (or maybe it’s just because, like every new parent, they’re just really excited to watch their plants grow and want to be involved as much as possible).
Despite the good intention, overwatering cannabis plants can have detrimental consequences. For example, overwatering cannabis can result in “root rot” wherein the root system cannot get a sufficient amount of oxygen. Characteristics of root rot include curled, yellowing leaves and brown roots that may be twisted together as an indication of infection.
Preparing to Water Your Cannabis Plant
It’s important to water your cannabis plant often (but not too often), and it’s important to use the right kind of water, too. So how do you prepare your water for a marijuana plant? You begin by choosing the right planter in the first place.
Bearing in mind that you’ll want to transplant your plant only once (at most) during it’s growth cycle to minimize stress, find a pot that will be large enough to hold a mature plant with ample room for root expansion. The pot should also have drainage holes or at least have the capacity to gain some using a drill or some other hole-poking mechanism. Standard 5-gallon hardware store buckets work well but there are many cannabis-specific grow pots that serve the purpose, as well.
Next, it’s time to prepare your water. Tap water is fine but it should be left out for at least 24 hours to settle pH levels (also, room temperature water is less likely to shock your plant). Once settled, measure the pH level of your water using basic testing strips then adjust the pH level using pH down solution according to your specific needs. Generally, soil requires a pH level between 6.0 and 6.8 whereas other grow mediums require pH levels between 5.5 and 6.0. Check with your garden supplier about your specific grow medium’s pH requirement.
After the pH has been adjusted, it’s time to add nutrients (provided your plants are past the seedling phase). Because nutrients can cause shock to plants if introduced too quickly, we recommend starting with about half to ¾ the recommended “dose” of nutrients according to the product label then slowly adding more until the full “dose” is reached. Do not exceed one full dose of nutrients (according to package instructions) because this could burn your precious plants. If nutrient burn does happen, don’t worry. Just act fast to flush the nutrients out of the soil before dropping the dose down again.
How Frequently to Water Cannabis
Seedlings dry out quickly and therefore need a lot of attention. Depending on the environment, seedlings may need to be watered twice daily but only with a small amount of water each time. Larger plants, on the other hand, should be allowed to dry out slightly – but not too much! This gives the roots a chance to breath and expand as they look for a water source.
It’s important not to let your plants go too long without water. Though some may be able to recover from drought, excessive dry periods could cause flowering plants to turn hermaphroditic.
Generally, larger plants should be watered every 2-3 days in the early morning (or as soon as the lights turn on for indoor grows) to improve nutrient absorption and reduce the chance of mold. Remember that the frequency of a watering schedule will vary by grow medium and environmental conditions. A good rule of thumb to determine if your plant is ready to be watered is to your finger in the soil up to your first knuckle (around 5 cm). If the soil is dry, it’s time to water. If the soil is still wet, hold off for another day.
Watering Your Cannabis Plant
When it’s finally time to water, the technique is pretty simple. Using a watering can for smooth, gentle distribution, pour your nutrient-rich water over the entire surface of the soil or grow medium. Water thoroughly until you see excess water drain from the bottom of your planter. Some suggest allowing roughly 20 percent of the water added to drain off as this helps ensure all nutrients will be evenly distributed throughout the root system.
Two weeks before harvest, flush your plants with pure, ph-balanced, room temperature water to remove any unused nutrients, improve the taste of the bud and reduce harshness of the smoke. To properly flush cannabis, pour a generous amount of clean water (instead of nutrient-enriched water) on the soil, allow it to sit for a few minutes to pick up residual nutrients, then flush with clean water again. Over the course of two weeks, the plant will consume any residual nutrients within the plant itself and wash away residuals in the grow medium.
Like all living things, cannabis plants need water to grow, but the frequency and amount of water they require will vary depending on their size, stage of growth, and grow medium. To help ease confusion regarding the best way to water cannabis plants, just follow our easy watering guide.