If you’re new to cannabis cultivation, the biggest mistake you can make is also the easiest and the most common:
Taking things for granted when it comes to watering.
Ensuring cannabis plants are provided with the right amount of water isn’t as easy as some expect. This is because there isn’t an exact science for watering a cannabis plant. Along with the size, type and location of the plant, you also need to consider atmospheric conditions and the fact that all cannabis plants are constantly growing and changing in some way.
All of which adds up to a very tricky balancing act to pull off.
On the plus side, there’s a good handful of universal rules and guidelines that can simplify things at least a little.
How Often Do Cannabis Plants Need Watering?
It’s actually far more common to overwater cannabis plants than to compromise their health through dehydration. Growers often fall into the trap of assuming more is better…when it isn’t.
There’s a general rule of thumb (no pun intended) when it comes to determining if and when you cannabis plants need to be watered. Stick one of your fingers into the soil to a depth of around 2 inches. If this top layer of soil is dry, you’ll want to give your plants a drink.
That is, assuming there’s decent drainage at the bottom of the pot or container, which there should be.
Over time, you might also be able to detect when your plants need water simply by lifting the pots and feeling their weight. Lift the pots at a time your plants need watering, then lift them again after adding the water. Note the difference in weight and use this in future as a guide.
If you leave your plants with insufficient water for too long, the first warning signs you’ll see is weakness and drooping leaves. The whole plant appears somewhat lifeless and limp, which may or may not be accompanied by yellow or brown leaves. This is where things become tricky, as an overwatered plant looks surprisingly similar. The only difference being that with overwatering, the tips of the leaves tend to curl, and the colour remains dark green.
In any case, it’s always better to err on the side of caution. In this instance, that means avoiding overwatering at all costs. Overwatering can be far more dangerous (or even deadly) than underwatering, so keep a close eye on your generosity when you water.
How Much Water Should You Use?
As already mentioned, there’s no exact science or rule when it comes to water quantities. This is because you’ll need to take into account a variety of factors, including the size of the plant, the ambient temperature, its growth stage, its overall health and the growing medium you’re using.
The idea is to give the soil a good top-to-bottom dousing, but never to such an extent that residual water sits on the surface of the soil. It’s essential to ensure that the pots and containers you use provide adequate drainage, allowing excess water to run through. If you’re growing cannabis outdoors in open earth, you needn’t worry too much about drainage.
You’ll also need to consider the size of the container. Properly watering tiny plants in massive containers can be tricky, as can adequately hydrating larger plants in overly compact pots.
If in doubt, it’s worth remembering you can always pick up an electronic moisture metre and/or alarm of some kind. Positioned directly in the soil, these gadgets are designed to indicate exactly when your plants need a top-up. Not strictly necessary, but useful nonetheless.