When cannabis is grown outdoors in garden beds, plants can normally spread their roots without restriction. However, when we grow cannabis in containers, plants becoming “root bound” can become a problem. Find out what root bound means; how to recognize it, and what you can do if it happens to you.
Most cannabis cultivars, at least in colder climates, grow indoors in a tent or in a dedicated grow room. Growing indoors in containers means there is the risk of your plants becoming root bound. When this happens, it can lead to all sorts of growing problems. Let us take a closer look at what “root bound” means. Learn how to recognise the signs, so you can fix the issue and prevent it from happening in the future.
WHAT IS ROOT BOUND?
When your plants are root bound, it means that the roots have outgrown their container and don’t have any more room to grow. This of course happens when your containers are too small for any given reason. Outdoors in garden beds, plants becoming root bound is less likely, although it can happen when roots hit restricting barriers such as pipes or large rocks underground.
WHAT ARE THE SIGNS OF YOUR PLANTS BEING ROOT BOUND?
A healthy root system plays a vital part for your plants’ growth. After all, it is with their roots that plants take in water and nutrients.
Plants becoming root bound can lead to all sorts of issues. Here are some of the most common signs and symptoms that your plants may be root bound:
Your plants may show symptoms of nutrient deficiencies. Among these signs could be yellowing, spots, or crumbling and wilting leaves. If you can exclude other issues such as incorrect pH, nutrient issues, and overwatering, your plants may indeed be root bound.
Containers Drying Out Too Quickly
When you find that the soil dries out after only a day or two and you need to water very often, it means that your plant needs more water than the container can hold.
Plants Get Way Too Big And Unsturdy
When your plants have grown too tall for their container size, they may easily tip over. This is usually a sign that your plants have become root bound, and that you should transplant them into bigger pots.
Other potential symptoms include:
- “Nutrient burn” without excess nutrients: If you spot the signs of nutrient burn, but you are feeding your plants only lightly.
- Smaller buds with stunted growth: If your buds grow smaller, or your plants’ overall growth is slower than usual.
- Sick plants, wilting, drooping: If your plants have a sick appearance or start to wilt or droop unexpectedly.
WHAT TO DO WHEN YOU SUSPECT YOUR PLANTS ARE ROOT BOUND
If your plants show one or more of these symptoms, you need to look at their roots to see whether they have become root bound. To do this, you will need to remove them from their containers. Sometimes, it may be quite obvious that your plants have outgrown their containers, say when you see the roots through the holes at the bottom. Time to give your plants a new and bigger home!
HOW TO SAFELY REMOVE PLANTS FROM THEIR CONTAINER
You want to be careful when you remove plants from their containers in order to not damage the roots.
Get a good grip on your plant’s stem, right above the soil line. Rest your hand on top of the soil so that the stem is between your fingers. Carefully flip over the whole plant and then try to pull off the container. Most of the time, the container should come right off.
If you have troubles pulling off the container, carefully squeeze the container a few times around the side. This helps to loosen up the soil inside.
If your plant is still refusing to come out, take a long knife and use the back edge to slide around the inner edge of the container. If your plant is so severely root bound that nothing will help to remove it, consider breaking open the container as your last option.
FREE THE ROOTS: HOW TO LOOSEN THE ROOT BALL
When you have managed to pull out your root bound plant from the container, the roots will be running in a tight circle in the shape of the container. The roots are trapped and unable to grow freely any longer. Before you replant into a bigger container, you should try loosening the compact mess of roots so they can spread out again. You can carefully do so with your fingers.
PRUNING THE ROOTS
In severe cases of root bound plants, you may not be able to loosen the root ball with your fingers alone. You will then have to prune the roots to free them. By using a sharp knife, cut a few top-to-bottom incisions into the outer layer of the tightly-packed root ball. But be very careful and only cut thin roots. Do not cut any thick tap roots! 2-3 incisions evenly spaced out around the root ball should be all that you need to free the roots so that they can grow outwards again.
REPLANTING YOUR CANNABIS PLANT INTO A NEW CONTAINER
Take a new container with enough room so that your plant’s roots have plenty of space to expand. Fill the container with some soil, make a hole, and then align your plant in the middle. Make sure that your plant is at about the same soil level as you had it before. Likewise, ensure that you do not pack the soil too tight; the roots should be able to grow freely without trouble. After you have placed your plant in its new container, water the soil. At this point, you can also add root stimulant to help with things.
Your previously root bound plant is now happily sitting in its new and big container, but it is going to be quite sensitive for some time. To help it to recover from the transplant shock, you should keep stress levels low for a few days. Feed it only lightly and if you can, turn down your lights a notch or two as well. You will know that your plants have fully recovered once you see new, healthy growth. When this happens, which can take between a few days to a couple of weeks, you can return to your normal lighting and feeding schedule.
HOW TO PREVENT YOUR CANNABIS PLANTS FROM BECOMING ROOT BOUND
Preventing your plants from outgrowing their pots and becoming root bound is not difficult. Simply choose large enough containers from the start so this won’t ever happen. If you plan to replant during a grow, up-pot into bigger containers before it’s too late. Don’t wait until your plants have outgrown their current containers.