Why Are My Tomato Plants Growing So Tall? (3 Things You Should Know)


Sometimes, young tomato plants will grow tall and thin, stretching themselves out. Other times, your tomato plants seem to grow at a pace that is completely out of control. I have seen this happen in my garden before, and you may also be seeing it in your garden this year.

So, why are your tomato plants growing so tall?  Young tomato plants grow tall and thin (spindly) due to lack of sunlight. Tomato plants also grow tall without flowers or fruit due to over fertilization, especially with high nitrogen levels. Tomato plants grow tall if you plant an indeterminate variety (some can reach heights of 9 feet or more!)

Of course, there are ways to prevent the problem of extremely tall tomatoes.  If you are already experiencing this problem in your garden, there are ways to fix it without losing your crop.

In this article, we’ll take a closer look at why tomato plants grow so tall. We’ll also give you some steps you can take to address the problem in your garden.

Let’s get started.

(If you like, you can also watch a video version of this article on Youtube or below).

Why Are My Tomato Plants Growing So Tall?

As mentioned before, tomato plants can grow tall for several reasons, including:

  • lack of sunlight (often leads to leggy tomato plants or stretched out seedlings)
  • over fertilization (usually due to excessive nitrogen)
  • planting an indeterminate variety (indeterminate tomato plants grow much taller than determinate varieties)
tomato seedling
If a tomato seedling does not get enough light, it will grow tall and thin as it stretches to reach the light. This leaves you with a leggy tomato plant

The table below summarizes the three main causes of tall tomato plants and when you might see it happen.

ScenarioLikely Cause
Seedlings
tall & thin
(“leggy”).
Lack of light
makes young
plants stretch
as they seek
more light.
Tall plants,
with few
or no
flowers
and fruit.
High nitrogen
levels cause
lots of green
growth, but
few flowers
and fruit.
Tall plants
with fruit
and also
flowers.
The plant is
indeterminate,
which will keep
growing until
frost stops it.
This table summarizes scenarios
when you might see tall tomato
plants and what causes it.

Let’s do some digging to find out just how tall tomatoes grow. Then we’ll get into how you can prevent or fix the problem of tall tomato plants.

How Tall Do Tomato Plants Grow?

The average height of a tomato plant depends on the type. Many determinate tomato varieties grow 5 feet tall at most, while indeterminate tomato varieties can grow to a height of 8 feet or taller!

tomato plant
Some indeterminate tomato varieties can grow to a height of 8 feet or taller! The variety has a big impact on the height of tomato plants.

Tomato plant height can vary quite a bit between different types. How high tomato plants grow also depends on the care you provide (environmental conditions) and pruning (more on this later!)

For example, Tiny Tim tomato plants only grow to 1 foot tall, while the Guinness Book of World Records suggests that the tallest tomato plant was 65 feet tall!

cherry tomato plant
Most cherry tomato varieties are indeterminate, meaning that the plants will grow quite tall during the season.

You can learn about all kinds of micro dwarf tomatoes (that only grow to a height of 1 foot!) in my article here.

Remember:

You can learn more about the difference between the two types of tomatoes in this article.

It might be that your tomato plants are tall due to the variety you have chosen. However, that might not be the only reason.

Tomato plant height is affected by several other factors as well.

Let’s take a look at what can cause tomato plants to grow tall (and how you can address the issue).

Your Tomato Plants Are Tall & Thin Due To A Lack Of Sunlight (Leggy Tomato Plants)

According to the University of New Hampshire Extension, tomato plants require full sunlight, growing best in areas that receive full sun for most of the day.

sunlight through forest
Tomato plants need full sunlight, so they may grow tall and thin when trying to reach for the light in a shaded location! This leaves you with spindly tomato plants.

If your tomato plants are not receiving enough sunlight during the day, they will grow “spindly” (tall and thin) instead of thick and strong.  This happens because the plant is stretching itself out to grow as tall as possible.

This will happen if there is not enough sunlight reaching the plant in its current location.  It can also happen if other nearby plants are blocking sunlight from the tomato plant.

tomtao seedlings
Don’t put tomato plants too close together (or close to other plants), since this can cause competition for sunlight.

You don’t want your plants to grow spindly, since this will decrease your tomato yield at harvest time.  So how can you prevent tall and spindly tomatoes?

First, plan ahead and check the location of your garden to make sure your tomato plants will get enough sunlight during the entire growing season. If there are any trees directly overhead, trim the branches or cut down the entire tree.

daylight
If trees are blocking sunlight to your tomato plants, prune some branches off to provide more light.

If that is not practical, then consider moving the tomatoes to another spot in your garden.  You can even move the entire garden to a brighter spot in your yard to take advantage of more sunlight hours.

Also, make sure that your garden is not too close to a house, barn, or garage.  Otherwise, the structure can block sunlight during the day and cause your tomato plants to grow tall and spindly.

garden shed lattice trellis
Don’t plant tomatoes too close to a shed, barn, or house that might shade them and cause them to grow tall and thin (spindly).

Finally, you should regularly check the amount of sunlight your tomato plants are getting during the growing season.  If there are taller, leafy plants nearby (including other tomato plants!), they may be competing with the tomatoes by blocking some of their sunlight.

To prevent this problem, be sure to use adequate spacing between tomato plants.  The spacing for tomato plants will vary depending on the variety.

A good general rule is 1 to 3 feet (30 to 91 centimeters) between plants, with more space between rows. This space will also leave room to water, fertilize, harvest, and prune tomato plants during the season.

tomato plants with metal stakes
Remember to leave enough space (1 to 3 feet) between tomato plants. The distance depends on the variety, so check the seed packet or catalog.

For more information, check out this article from on tomato plants from the University of New Hampshire Extension.

Your Tomato Plants Are Tall Without Flowers Or Fruit Due To Over Fertilization

Tomato plants may grow very tall if they are over fertilized, especially with nitrogen-rich fertilizers.  The idea is that the nitrogen (the “greening nutrient”) causes the stems and leaves to grow large and thick, at the expense of flowers or fruit.

tomato flower
Excessive nitrogen causes tomato plants to produce lots of green growth but no fruit. Of course, you should also ensure proper pollination!

This sometimes makes for a tall tomato plant with few flowers or fruit.  Of course, a lack of fruiting can be due to inadequate pollination.

You can try to attract bees in your yard to improve pollination. You can also hand pollinate your tomato plants to help with fruit production.

electric toothbrush
An electric toothbrush is one way you can hand pollinate tomatoes.

(For more information, check out my article on how to hand pollinate tomato plants.)

You can also try blossom set spray, which causes flowers to set fruit, even if pollinators are nowhere to be found.  You can check out blossom set spray on the Gardener’s Supply Company website.

To avoid the problem of over fertilization, try using low-nitrogen fertilizers for your tomato plants.  For more information, check out my article on low-nitrogen fertilizers.

Your Tomato Plants Are Tall Because They Are An Indeterminate Variety

This is a common problem, since indeterminate tomato varieties will grow as long as they are able to do so. Generally, this means that they will keep growing until the first frost of the season.

frosted leaf
Indeterminate tomato plants will generally live and grow until the first frost of the season (possibly beyond if you protect them from cold).

In an area with a long growing season, this means that some indeterminate tomato plants will reach a height of 8 feet or even taller!

This makes it difficult for anyone to harvest the fruit on the top part of the plant.  It also increases the chance that the tomato plants will fall over in the wind (or due to the weight of its own stem, branches, and fruit).

ripe tomatoes on vine
Too much fruit on one tomato branch can lead to a broken branch or a plant that bends or falls over.

How To Keep Tomato Plants Short

Luckily, there are several solutions for the problem of tall tomato plants. You can use some or all of these ideas, depending on your situation.

Let Your Indeterminate Tomatoes Grow Up And Then Down

If your tomato plants are growing too tall, then simply double the amount of space they have available to grow!  Let them climb up one side and down the other side of an arbor.

An arbor is a garden feature that is often used at the entrance to a garden.  However, you can place an arbor anywhere in your garden and allow your tomato plant to grow up and over the structure.

arbor arch
An arbor makes a “living arch”, and you can use it to support indeterminate tomatoes so their height does not get out of hand.

This makes it much easier to harvest any fruit on the uppermost branches.  For more information, check out my article on arbors.

You can also let your tomato plants grow up and over an A-frame trellis.  An A-frame trellis serves the same purpose as an arbor, but with a pointed top instead of a flat or arched top.

yardnbarn A shape frame garden trellis
An A-frame trellis allows tomato plants to grow up one side and then down the other side, making it easier to harvest from tall indeterminate varieties.

If you have a wall to mount it against, an ordinary trellis can also help to support your tomato plants. Here are two trellis options from Ace Hardware:

For more information, check out my article on trellises.

As an added bonus, you can plant shorter, shade-tolerant plants (such as lettuce or spinach) beneath the arbor or A-frame.  This will save space in your garden and allow your plants to help each other to grow!

Provide Taller Supports For Your Indeterminate Tomato Plants

You can also use taller stakes instead of cages if you need more height to allow your tomato plants to grow.  Remember that cages are more useful for determinate tomato plants that only grow to a height of 3 to 5 feet.

tomato plants with twine rope stake
Indeterminate tomato plants need stakes or twine for support. A tomato cages is not tall enough.

Also, remember that you will need to drive a good portion of the stake into the ground to keep it steady. Otherwise, you run the risk of the entire stake falling over due to the weight of the tomato plant.

This means that you will want a 10-foot tall stake, driven 2 feet into the ground, in order to give a tomato plant 8 feet of pole to climb.

For more information, check out my article on how to support tomato plants.

Prune (Top) Your Indeterminate Tomato Plants

Sometimes, even the use of arbors, A-frame trellises, and tall stakes are simply not enough.  Your indeterminate tomato plants may just be too tall, and you cannot give them the space they need to grow.

tomato plants with stakes
These tomato stakes will suffice for now, but they may not be tall enough later in the season.

In that case, you can “top” them, or prune the top part of the plant away. This will prevent them from falling over after they outgrow their supports.

Topping tomato plants prevents the tomato plant from getting too tall.  As an added bonus, you can make new plants by planting the trimmings from the tops of the plants.

tomato branch cut off
You can plant a pruned tomato branch and get a whole new plant to grow!

In order to top your tomato plant, cut off the top part of the main vine (the part that is growing higher than you would like).  You may be able to snap off the top of the stem using your fingers and hands.

If not, sanitize a knife or pruning shears with alcohol to use for cutting.  Clean the knife or shears with alcohol between each new cut, to avoid spreading disease between your plants (better to be safe than sorry!)

pruning shears
If you use pruning shears to top your tomato plants, be sure to clean thoroughly with alcohol between cuts to avoid the spread of diseases. Pruning tomato plants with clean tools should help to prevent disease from spreading.

One important thing to remember is that you should not remove too many leaves at once when pruning your plant.  Otherwise, you might expose the fruit on the tomato plant to sunscald.

Sunscald occurs when intense direct sunlight causes white or yellow spots on the fruit of tomatoes (or peppers).  For more information, check out this article about sunscald on the Joe Gardener website.

sunscald on tomato
Your tomato fruit may get sunscald if you prune off too many of the upper branches and leaves from the plant.

Finally, if you want to get new plants after topping a tomato, simply plant the trimmings deep in the soil to create new plants. Tomato plants can grow new roots from their vines, so you can bury them deeper than you think.

For more information, check out my article on why to plant tomatoes deep in the soil.

When To Top Or Prune Tomato Plants

A good time to top or prune tomato plants is when the growing tip (highest part) of the plant reaches the top of the support (stake, cage, or trellis). Topping or pruning is a good way to reduce vine height if you want to keep your tomato plants short.

tomato stakes
When your tomato plants reach the top of their support (stake, trellis, etc.), you can top them to reduce their height.

If you are trying to keep your tomato plants neat, you can remove suckers by pruning any time they appear. This will help to prevent bushy tomato plants and make them much easier to care for and harvest from.

Conclusion

The table below summarizes the scenarios when you might see tall tomato plants and what causes it.

Now you have a much better idea of why your tomato plants are growing so tall.  You also know how to prevent the problem, and how to keep tomato plants short.

You can learn what to do with tall plants here.

If your tomato plants are too tall with no fruit, check out this article on why it happens (and how you can fix it).

Want more information about growing tomatoes? Check out my article on the top mistakes to avoid when growing tomatoes.

If you want to learn some interesting facts about tomatoes, check out my article on where tomatoes are from.

I hope you found this article helpful – if so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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