Root Bound Tomato Plants: How to Identify and Fix Them

Quick Summary: Root bound tomatoes have roots circling into a dense mat from being in a too-small container too long. Signs include roots spilling from drainage holes, stunted growth, and misshapen leaves. Fix by gently loosening the root ball before transplanting. Prevention: pot up seedlings when they have two sets of true leaves, and use containers of at least 10 gallons for mature plants. Read time: 5 min | Experience level: Beginner

Jump to: Causes | Identifying | Fixes | FAQ

Root bound tomato plants are one of the most common problems I see at farmers markets when customers bring me their struggling seedlings. The roots have circled into a dense mat at the bottom of the pot, and the plant is essentially strangling itself.

This happens when seedlings stay too long in small containers, which is common with big box store purchases and with home growers who don’t pot up in time. The good news: root bound plants are fixable if you catch them before transplanting.

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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.

Given water and light a tomato seedling continues to grow until the roots reach the limits of its container. At this point the roots have no where else to go so they start to circle around each other forming a dense mat that can result in stunted growth.

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 however, especially tomatoes.

A tomato seedling becoming root bound in the early stages of growth can stunt the plant and cause problems throughout the rest of the season!

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:

What Causes Root Bound Tomato Plants?

The most common situations where root bound tomato plants are likely to show up include:

• Purchases from commercial outlet. 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 as the season progresses. You can learn more on what to look for in the post on choosing healthy tomato seedlings.
• You waited too long to pot up. If you start your own tomatoes from seed and they 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. It is not only the seedling stage where tomatoes can become root bound. Sometimes it 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.

How Do You Identify a Root Bound Plant?

Roots Spilling Out of the Drainage Holes

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 the plant is root bound.

Stunted Growth

After a plant has developed 2 sets of true leaves it should start growing fairly quickly given light. If the plant just sits in the pot and doesn’t seem to increase in size, it may be stunted from being root bound for too long.

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

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 the roots are growing into a dense mat around the bottom of the pot., it is probably root bound and may need some TLC.

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

How Do You 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 outdoors 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 robust. 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. It will recover within a few days. Breaking a few roots is fine

If you’re working with seedlings, remember to be sure to harden them off before transplanting into the garden or into larger containers as soon as possible for the best results.

FAQ

Check out this comprehensive guide to growing tomatoes for the best flavor. This guide is a must-have if you want to grow your own tomatoes, heirloom or hybrid.