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Root Bound Tomato Plants | Signs & Fixes

Root Bound Tomato Plants | Signs & Fixes
Home » Grow Your Own Food » Root Bound Tomato Plants | Signs & Fixes

If young tomato plants are left growing in a small pot or plug for too long, they can become root bound. In order to give them a chance to thrive in the garden, they need a little help from you to free up their root ball. Find out everything you need to know about root bound tomato plants and how to fix them!

Jump to: | What Is “Root Bound”? | Identifying Root Bound Tomato Plants | Fixes For Root Bound Tomato Plants

Glove holding a plant that shows signs of being root bound.
Plant that shows signs of becoming root bound

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What Does Being Root Bound Mean?

In horticulture, a plant being “root bound” refers to the roots having formed a dense, tangled ball as a result of lack of space. A plant doesn’t tend to realize that it has reached the limits of its container, so the roots keep growing, going round and round the pot and sometimes causing severely stunted growth.

Root bound plant showing roots circling around the root ball due to being in small pot too long.
Root bound plant showing circling off roots

Many houseplants don’t mind being a little root bound and can stay in the same container for years. The same doesn’t go for garden crops, especially tomatoes. A seedling becoming root bound in the early stages can really get it off to a bad start!

Fear not. With a little extra TLC, you will be able to get those root bound tomato plants back on track so they look like this if you could peek into the garden soil:

Illustration showing a healthy root system of a plant below ground.
Healthy root system below ground

How To Identify Root Bound Tomato Plants

There are three common situations in which you may encounter root bound tomato plants. It usually happens in the seedling stage, because after all, that’s when the plant and roots grow the quickest.

  • You bought root bound seedlings. If you buy tomato seedlings from big box stores, it’s not uncommon to encounter ones that are root bound. They’re often kept in smaller seedling pots or even those six-celled trays and not potted up on time. You can read more in the post on choosing healthy tomato seedlings.
  • You waited too long to pot up. If your indoor-germinated tomato seedlings are growing well but it’s still too cold to bring them outside, you should repot them into 4″ planters when they have two sets of true leaves. They outgrow the smaller celled trays faster than you can say “root bound”!
  • The container you’re using is too small. Sometimes tomato plants become root bound past the seedling stage. This can happen if the grow bag or container you’re using is too small. Folks love those typical 5-gallon pots, but for most tomato varieties, you actually need 10+ gallons or your harvest may be limited. You can find more information in the post on growing tomatoes in pots.
Root bound plant outside of pot that was too small for its growth.
Root bound plant grown too long in a pot that was too small

Below, let’s have a look at how to recognize root bound tomato plants.

Roots Spilling Out Of The Pot

When a plant gets root bound, the roots will look for any possible way to continue growing. In many cases, they’ll end taking the only possible route: out of the pot. If roots are spilling out of the drainage holes, this can be a good indication that you’ve waited too long to repot.

Stunted Growth

If you’ve started tomato seedlings at home before, you’ll know that as long as they get enough light and water, they grow crazy quick. If yours are not growing like you’d expect them to, looking small and maybe a bit sad, they may need a little more space.

Misshapen Leaves

One thing that often happens with stunted and root bound tomato plants is that new leaves come out… strange. What happens below the soil is always reflected above the soil as well! If new leaves are small, curly, pale or just generally unhealthy-looking, it’s probably time to take a look at the roots.

Check The Roots

Hand holding tomato plant that is not in a pot and shows the root ball.
Tomato plant showing signs it is time to plant or pot up

That brings us to the last point. If your tomato seedlings are showing the symptoms discussed above, your best bet is to take a peek at the roots. This will quickly confirm whether they’re root bound or not.

All you have to do is gently grab the plant at the base of the stem. Give the planter a few squeezes to loosen things up. You should then easily be able to lift the whole thing out of the pot in one go.

If there are lots of roots growing around the edges, forming a dense mat, then you’ve got a root bound plant on your hands.

TIP: If your baby tomato plants are struggling but you’ve concluded it’s not root binding, have a look at the full post on problems with tomato seedlings to help you identify what’s really going on.

How To Fix Root Bound Tomato Plants

So what should you do if you’ve got one or more root bound tomato plants on your hands? Don’t worry, getting them back on track is easy.

If it’s not possible to place them in full soil in the garden (yet), here’s what you can do to set your tomatoes up for success, whether they’re seedlings or adult plants:

  • Take the plant out of its pot.
  • Loosen the roots. Sometimes you can gently do so with your fingers, while in other cases you have to be a bit more harsh about it. It’s okay, breaking a few roots is not a problem.
  • Repot into a larger container with fresh, well-draining soil and a little compost.
  • The plant may look a little sad for the first few days, especially if you broke a good few roots. Don’t worry: it should perk back up soon.

If you’re working with seedlings, remember to be sure to harden them off and then transplant them into the garden or into full-size grow bags/containers as soon as possible for the best results.

Young tomato plant against hogwire fencing as support system.
Young tomato plant against hogwire fencing as support system.

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