While watering marijuana plants may seem like one of the simplest parts of caring for them, it can, in fact, get rather complicated. New growers often run into issues and questions that they never expected to have. One of those questions is simply when to water your marijuana plants. The answer to this question ties into tendencies to overwater as well as underwater your plants, so pay close attention.
Choosing the right container
One step that is often neglected among new marijuana growers who are trying to figure out everything for the first time is simply using the right kind of container for your marijuana plants. This may seem like it has nothing to do with watering your plants, but it is actually surprisingly important.
First of all, if your marijuana plants are in containers that are too big for them, the tendency to overwater them will be much greater. While this can be a risk for your plants, it can also be used as a tool to compensate for your natural tendencies. For instance, if you generally are not watering your plants often enough, you can move them into bigger containers because they should be fed less often when living in such containers.
The same goes for small containers — but opposite. Because smaller pots don’t hold water for as long, plants living in these little containers will need to be fed water more often. Therefore, if you tend to water your plants more often than you need to, it’s better to have them growing in a smaller pot because it will lower the risk of overwatering your plants.
Of course, under no circumstance should you keep your marijuana plants growing in pots that are too small for them. If you do that, it is likely that the roots will become root bound, which means they will grow around the edges of the pot until they have formed a wall of sorts. This wall will keep water in for too long (leading to root rot or fungi development), or won’t allow the proper amount in to begin with.
An equally important aspect to consider when choosing a container for your marijuana plants is the holes at the bottom and the water runoff that will go through them. When you water your plants, you should see between 10% and 20% of the water put in trickle down and out of the bottom of the container. This is how you will know if the holes are draining properly as well as if you have given your marijuana plants enough water.
This water being flushed out is good for several reasons. First of all, it takes any of the salt that has been building up out with it. If these salts and fertilizers sit in the soil for too long, they will start building up and lead to the imbalance of the pH levels as well as difficulty for your plants’ roots in accessing the nutrients that they need.
If the water takes a long time to make it out of the bottom of the container, you will know that there are some sort of issues. There is either a problem in the soil (which needs to be a quality soil that drains well to begin with), in the pot, or in the roots of the plant. You should be especially concerned if you don’t see any water flushing out the bottom of the container at all.
When to water
You should water your marijuana plants when the soil is dry. That sounds simple enough, but of course, there are always times when you will end up asking, “does this qualify as dry enough?” So instead of wondering, there is a good rule of thumb you can follow to be relatively certain that it is safe to water your plants now without giving them too much.
First of all, simply poke your finger into the soil your plants are growing in. Push the finger down just to the first knuckle (about an inch deep), and then see if it is dry the whole way. If it is, it is safe to water your plants now. If there is still some moisture within that first inch-thick layer, it is better to wait a bit longer before you water your marijuana plants again. Remember, it is much easier to overwater your plants than underwater them.
Keep track of when you watered your plants last because that will help alert you to whether there are any problems with the soil that you can’t see. For instance, if the soil remains damp or moist for longer than five days without drying out, then you can be relatively sure that there is some sort of draining issue.
If you would prefer a different way of checking whether your plants need to be watered, you can do it by weight instead. The key is simply not to water your plants until you lift the pot and feel that it is light. To get acquainted with how light it should be, you can fill a container of the same size up with dry soil for comparison. Once the pot with the plant feels like it is nearly as light as the other pot, you can water it.
What to do with a drainage problem
If you have identified a drainage problem in your marijuana plant containers, then the time has come to take action to fix the problem. One way is to put in some perlite so the soil will be loosened and will allow for better drainage. Another way is to use a smart pot instead of a regular one — these pots are made of fabric and help your roots access plenty of oxygen. Whatever you do, do not use bark or wood chips to loosen up the soil, as marijuana plants do not do well with these materials.
Identifying a watering problem
Sometimes the problem comes from you and your watering habits. If you have been under watering your plants, you will notice that they are wilting and starting to appear lifeless, their leaves limply hanging. Sometimes the plants will get to the point of looking and feeling crispy as if they are all dried up. If you don’t give them more water soon, the plant will certainly die. Luckily correcting this is simple — you just need to add more water or start watering more frequently.
Overwatered plants droop instead of wilt or their leaves begin to curl down. The leaves will remain firm rather than limp, and will slowly start to turn yellow in color. Overwatering your plants is actually more about depriving the roots of getting enough oxygen. Don’t water your plants for a while and then adjust your watering schedule to fix the problem.
Written by Robert Bergman, founder of ilovegrowingmarijuana.com. Robert has been growing cannabis passionately for over 20 years and shares this insight to educate growers avoid mistakes and to fully capitalize on a bud’s potential and get the most out of a marijuana plant.