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Growing healthier tomatoes and tomatillos via adventitious roots

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Learn how to use the adventitious roots on your tomatoes, tomatillos, and other garden plants for healthier seedlings and more productive adult plants!


What Are Adventitious Roots?

Adventitious roots are roots that form from non-root parts of the plant in response to environmental/growing conditions, physiological stress, or injury. Not all plants have the ability to form adventitious roots.    

When you conjure up an image of plant roots, you probably think about the branched network of underground plant material that a plant uses to slurp up water and nutrients. Those are referred to as a “primary root system.”

However, some plants have developed the ability to reprogram cells to adapt to whatever conditions those cells happen to find themselves in. For instance, plant tissue that’s currently functioning as the stem of the plant can reprogram to develop into adventitious roots under moist conditions or if the stem is placed in contact with soil.

Examples of adventitious roots in common edible garden plants

Maybe you’ve had a tomato plant flop on the ground, been too lazy or forgetful to upright it, then come back weeks later to find its above-ground stems rooted into the ground… Those are adventitious roots!

Or have you ever noticed your sweet potatoes or winter squash plants climbing along the ground and setting roots at each leaf joint? Those are adventitious roots as well!

Now, before you think you can go out and bury the stems on all your plants and they’ll just develop new root systems, let us repeat that not all plants have adventitious roots. For instance, if you bury the trunk of a cherry tree, you’re almost certain to kill it rather than force it to develop new roots. 

However, for certain types of plants, you can use their ability to form adventitious roots to your advantage, growing healthier seedlings and more robust, productive, and resilient plants (as we’ll detail further below in this article). 

Trichomes versus adventitious roots: what’s the difference?

Ever notice tiny hair-like structures on the stems and leaves of certain plants? These are called trichomes

If you look closely at the stems and leaves of a tomato plant (or closely related plants like ground cherries and tomatillos), the fuzzy trichomes are very easy to spot. 

There are different types of trichomes with different functions. Depending on the type of trichome, it may:   

  • collect sensory data from the environment,
  • fend off or even capture pest insects,
  • prevent disease/pathogen spread, 
  • excrete insect-repelling chemicals,
  • cool or warm the plant, 
  • prevent sun damage
Here you can see the difference between hair-like trichomes (red arrows) versus bumpy, adventitious root buds/primordia (blue arrows) on the stem of tomato plant.
Trichomes versus adventitious roots. Hair-like trichomes (red arrows) versus bumpy, adventitious root buds/primordia (blue arrows) on the trunk of a tomato plant.

On the tomato plant pictured above, you can see the difference between: a) the bumpy, adventitious root buds along the trunk of the plant (denoted with blue arrows), and b) the fuzzy trichomes (red arrows) on the stems and leaves.  

How to use plants’ adventitious roots in your garden

Some of our favorite plants that form adventitious roots are tomatoes, tomatillos, and ground cherries. This root-forming feature primarily comes in handy at two stages:

1. Potting up seedlings.

We often start our seeds in Ladbrooke soil blocks or small cells to conserve space. This means we have to “pot up” the seedlings into larger containers about 4-6 weeks after they’ve germinated so they don’t get too root bound.

When we pot up our tomatillos and tomatoes, we do the following:

  1. Remove the two cotyledon leaves (the first leaves that emerge after the seed germinates), and
  2. Bury the stems (up to a couple inches below the next set of branches).

This allows the seedlings to form adventitious roots and develop a more extensive root system. That process then translates into greater water and nutrient uptake potential.

Potting up tomato and tomatillo seedlings into larger containers. 1. Notice the red arrows pointing out the cotyledon leaves which will be removed (you can clip them off with your finger nails). 2. Red arrows show seedling after cotyledon leaves removed. 3. Seedlings are potted up into larger containers with their stems/adventitious roots buried below the soil surface to allow for more extensive root system development.
Potting up tomato and tomatillo seedlings into larger containers. 1. Notice the red arrows pointing out the cotyledon leaves which will be removed (you can pinch them off with your fingernails). 2. Red arrows show seedling after cotyledon leaves removed. 3. Seedlings are potted up into larger containers with their stems buried below the soil surface to allow for the development of adventitious roots and more extensive root system development.

2. Transplanting outdoors.

As we wrote about in 5 Tomato Growing Tricks, we also take advantage of adventitious roots when transplanting our tomatillos and tomatoes outdoors.

Rather than simply plunking the root ball in the ground, we again remove the lowest branches/leaves, then bury the plant on its side. If you live in warmer climates, you can simply dig a deeper hole and put the plants in the ground vertically. However, doing this in cooler climates means your tomato plants’s roots are in cooler soil, which can reduce fruit set, hence our recommendation to bury the plants sideways. 

If you’ve never used this tomato transplanting method before, it can make you feel like you’re doing something wrong and/or killing your plants. However, what you’re doing is triggering the development of adventitious roots, thus creating a more extensive root system. This sets you up for healthier, more resilient plants that need less irrigation and fertilization.

Step 1: note the removed stems. Step 2: disrupting the soil as little as possible, dig a trench; fertilize with a slow release organic fertilizer or compost if necessary. Step 3: bury the plant sideways, covering the stem (which will strong new vertical roots). Put mulch back over the soil surface and add a stick next to the stem to prevent cutworms (the
Step 1: Remove lower leaves and stems other than uppermost growth. Step 2: Disrupting the soil as little as possible, dig a trench; add worm castings or finished compost. Step 3: Bury the plant sideways, covering the stem to just below the first leaves. Then put mulch back over the soil surface and insert a stick next to the stem to prevent cutworms (aka the “stick trick”).

Three warnings about adventitious roots:

1. Plant disease introduction 

As Clemson University Extension mentions, a possible risk with removing the lower leaves/stems and burying your tomato transplants is the potential for disease organisms to infect your plants through the wounded tissue (example: bacterial wilt).

If you’re rotating crops and/or using good compost or worm castings in your planting holes (here are the worm castings we recommend), you can minimize the likelihood of plant infection.

2. Colder climates, lower yields  

We live in a warm, southern climate, and the tips outlined above work great for us. However, we’ve heard from a good grower living in a cooler climate who says that their tomato plants don’t produce as much when they bury the roots during transplant.

They speculate this is because tomato plants love heat, and burying them too deep keeps their roots in cooler soil, which may inhibit productivity. If you live in a cooler climate zone, experiment with different methods to see which works best for you. As mentioned above, this is why we recommend transplanting your seedlings sidewise into a trench rather than into a deep vertical hole. 

3. Not all plants can grow adventitious roots 

We can’t repeat this warning enough: not all plants can grow adventitious roots! If you bury a plant that can’t grow adventitious roots, you’ll kill the plant.

If you’re working with a new plant variety, do a bit of research to make sure you’re only using this method on plants that can grow adventitious roots.


We hope this information about adventitious roots helps you enjoy even more juicy, sun-ripened tomatoes and tomatillos this year.

Happy gardening! 

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2 Comments

  1. FYI: in #1 of Three warnings about adventitious roots you referred to a risk of removing lower stems. I bet you meant to say ‘removing lower leaves.’

    1. Thanks! Just edited to clarify. Depending on the size of the seedling, there may also be stems that need to be removed. Basically, you’re removing any leaves and stems other than the uppermost growth, then burying the primary stem.

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