How Deep Do Tomato Plants’ Roots Grow?

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Last Updated on January 20, 2023 by Urska

How deep do tomato plants’ roots grow? A tomato is essentially a very lazy plant!! Its roots grow as deep as they need to grow. There are a number of factors that govern how tomato roots grow, and how you need to tend to them.  This article should answer some of your deep-rooted tomato questions.

A Quick Note On Tomato Diversity

Tomatoes are insanely diverse fruits! I have grown giant Crimean black tomatoes, little cherry tomatoes, moneymaker, little wonder,  yellow pears, Beefsteak rainbows, cherry whites,  Japanese giant oxhearts, some weird thing that looked like a flame, and heaps of other things I cannot even remember the names of. When it comes to answering our question “How deep do tomato plants’ roots grow?” a lot will actually depend on the cultivar. Let’s have a look at a few factors that govern how plants grow.

Determinate and Indeterminate Tomotos

When we look at the incredible diversity of tomatoes out there, one thing is very useful. We can broadly divide tomatoes into two broad growth styles of plants.

Determinate Tomatoes

Determinate tomatoes stop growing when they flower and produce fruit. These tomatoes tend to look more bush-like and produce crops of fruit that all ripen at about the same time. In short growing seasons, or for balcony gardens I tend to like determinate tomatoes. When it comes to the question of “How deep do tomato plants’ roots grow?” I have found that the determinate plants have one set of deep roots.  If left to their own devices they will go about two feet into sandy soil. Shallower for better soil.

Indeterminate Tomatoes

These tomatoes just keep going – they can actually get a bit out of hand, much like a squash plant can. They take over! Classic wild cherry tomatoes are a good example here. These tomatoes just keep going. Every time a stem touches the ground somewhere, it will roots and just keeps growing. They make fruit and flowers and have no real plan other than just to sprawl over everything and make fruit.

I have had these beasts take over my garden, and it can actually become a problem. Eventually half of the fruits fall on the ground, and then for ten years after that, you have this seed bank in the soil that means you cannot get rid of these things. If you go away for two weeks in mid-summer and come back, these things will have covered everything in an impenetrable rainforest of tomato vines. The good news is that they taste good and you will get buckets and buckets of tomatoes.

With time, the genetics of these “wild tomatoes” means that the ones that are most adapted to your garden will become dominant, and each year the problem gets “worse”. My freezer is always full of tomato puree, tomato soup, and tomato chutney, and the pantry will fill up with sun-dried tomatoes if time permits. We will go into the root dept of these ramblers shortly.

Tomato Root Systems

Tap Roots

A tomato will produce a taproot where the seed germinates. Taproots grow down in a deep direct way and branch laterally. The depth of the taproot depends on the genetics of the plant you are growing, but I find it can range anywhere from about 8 to 18 inches depending on the plant, time of year, and soil.

Fibrous Roots

Fibrous roots do not have a central root such as is the case with a taproot. These roots branch out and do their own thing, but have no central stem. Tomatoes grown from cuttings will have a fibrous root system. When you have a rambling indeterminate tomato plant that comes up from a seed, it will produce fibrous roots wherever its stem touches the ground. This means that you can actually have a tomato plant that has both root systems! Fibrous roots tend to not penetrate as deep into the soil as taproots. I have never seen fibrous tomato roots extend more than about 5-7″ into the soil. These roots tend to hug the surface and follow the compost/humus layer on the top of your soil.

Combining All This Knowledge To Grow Amazing Tomatoes

Determinate Tomatoes

These tomatoes are best grown on a vine stand in my opinion. You can grow them in a pot or in the ground if your soil is healthy and full of compost and manure. If I had lots of money I would buy these for my tomatoes.

Instead, I just make do with a homemade trellis that I make out of some bamboo from a nearby river and this works very well too. It does not however have the aesthetic appeal. If you are using a potted system, good soil is important.

With regard to pot size, this really just depends on how much you wish to feed your tomatoes. I have a friend who has 20 000 tomato plants, and he grows these in little bags on the ground with some soil and nutrients on drip-feed. The bags are 5-6 inches deep, and a foot long. The tomatoes stand 7 feet tall when fully grown and yield huge crops. For the home grower, we do not have the technology at our disposal to be able to “mass produce” tomatoes, and the idea is instead to aim for quality and taste.

The deeper your soil, and the more you have, the more the tomatoes can scratch around in there for little pockets of trace elements and these give that “homegrown” taste. That is also “homegrown” health. You just don’t get that from commercial crops, so, if you can afford it, and have the space try to get a pot that is at least 18 inches in depth and the same width. Smaller works, but, when it comes to homegrown tasty tomatoes – pot size matters in my opinion.

Tomatoes are heavy feeders and determinate tomatoes can only feed in one place hence the constant provision of additional nutrients helps. You must remember that plants can be overfed with nutrients and will die. Just follow the instructions for mixing – do not overdo it. (As a side note, it really does not hurt if you pee on tomato plants – they thrive on this renewable source of nitrogen!! Naturally do not pee on the fruit.)

 

 

This is an example of a tomato planter I built for my Mom out of an old wine barrel. These are particularly good for growing little wonder determinate tomatoes. The barrel rings on the trellis allow my Mom to put bird netting around the planter to keep the birds out.

Learn more about: 5 Problems Related To Tomato Growth

Indeterminate Tomatoes

These tomatoes are suited to outdoor growing in your garden. I find I like to let them ramble a bit and also run up a few trellises from time to time. These are real free-range plants and just letting them do their own thing with a bit of intervention helps. They seem to know where they want to go, and what they are looking for. I often take a machete to the garden and just hack when they get too out of hand and go somewhere I don’t want them to. The rest of the time you can just let them climb up things and do their own thing. They require a lot less babysitting than determinate tomatoes and also seem to be more disease-resistant.

When we get to our question “How deep do tomato plants’ roots grow?”  With indeterminate tomatoes, it is not so much about the depth of the soil as the quality of soil in the bed you plant them in. The important thing here is to feed your tomato patch with manure and organic matter. I dump lawn clippings and manure in layers in the tomato patch area. You can keep doing this even while they are growing.

It appears that when tomatoes are in the ground it is nearly impossible to overfeed them. I have placed chicken manure, cattle, and goat manure on their roots and in some cases, this manure has been quite fresh. With other plants, this can kill them, but with tomatoes, they just get crazier. They are heavy feeders and when growing indeterminate plants, having lots of good soil around for them to put their roots in wherever they choose makes for the greatest yields. This is especially true for cherry tomatoes which in my opinion have the best taste of all tomatoes and also produce the best-tasting puree.

Have we answered our question? How deep do tomato plants’ roots grow? Sort of! There is no one size fits all, but my general advice is to give the plants more space than less. The fruit just tastes better if the soil is deep and rich. Homegrown tomatoes are one of the greatest summer treats in a garden. Ok, green peppers are better. But tomatoes are pretty amazing too. If you enjoyed this article please share!

Read more about: What Size Grow Bag For Tomatoes Is Ideal?

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