Leggy Tomato Seedlings | How to solve this problem

Tomato seedlings will go leggy if they are not getting enough sun when they are small and growing. The stems will stretch up reaching for more light becoming weak and bending over. This problem can be solved if it is caught early and the tomatoes are given more light. Provide the stems with support and they can strengthen their stems.

Leggy tomato seedlings can become weak in the stems and the plant can struggle when transferred to its space outside. If you are raising seeds yourself, leggy seedlings can occur if they are kept in too much shade.

Greenhouses are a great idea when raising seeds. In cooler weather but make sure they are in a bright spot to avoid your seedlings from reaching up to the sky to try to reach the light.

This article will explore all you need to know about why seedlings get leggy, how to fix leggy seedlings and how to prevent this problem.

This article contains affiliate links from Amazon. If you click the link this site receives a commission, at no added cost to you.

What are leggy tomato seedlings?

When tomato seedlings become ‘leggy’ this means that the stems are long and begin to flop over. This is caused by low light conditions. Tomato seedlings will have a single stem that will reach up and grow its first 2 leaves.

Tomato seedlings that are grown in low light indoors or outdoors in a greenhouse will continue to grow  a longer and longer stem so that the leaves receive light. Adding a brighter UV light indoors or finding a brighter outdoor space for your greenhouse is essential to prevent this problem.

Tomato seedlings are usually raised over winter so run the risk more than most seedlings of becoming leggy. For cold regions, raising seeds must be done in a greenhouse or even small green box.

Check this one out from Amazon if you want to grow tomato seedlings at home.

Place the box in a space that gets bright light but not direct sun otherwise it can heat up too much.

Why tomato seedlings get leggy

Tomato seedlings get leggy due to low light levels. Too much shade will cause the seedling to grow a long stem. When the top of the stem gets too long and the leaves are heavy the stem will bend over

The stems are thin and not strong enough to hold themselves up.

How to fix leggy seedlings

Tomato seedlings can be fixed through a few easy steps if this problem is caught early. Follow these easy steps if you have leggy tomato seedlings to correct this problem before it gets too far.

1. Support the seedlings

The first step is to support the tomato seedlings and stop them from flopping over. This can be done as easily as cutting the top off a clear soda bottle. Remove the soda bottle lid and place it over the top of the tomato seedling pot.

This works well if the seedlings are in a small pot or container. This will help to support the tomato seedling and also help to create some added humidity to encourage good growth.

If your tomato seedlings are larger than 3-4 inches, plant them out into your garden bed and use a small stake to support them. A piece of bamboo will work for this and the soda bottle can be placed over the top to give the tomato the extra support.

After 2-3 weeks the soda bottle can be removed and the tomato can be exposed to full light. This works perfectly in early Spring where the weather is still cool.

3. Place it in a bright position

The next step is to transfer the tomato seedlings to a bright position. This doesn’t need to be full sun but bright light throughout the day is important. This will allow the leaves to get the light they are looking for and promote larger leaf growth rather than more stem growth.

A greenhouse is great, but if you have placed the plastic soda bottle on top, this will act like a mini green house. Do this in early Spring when the weather is still cool.

4. Water them well and wait

Water is important when raising tomato seedlings and leggy seedlings will still benefit from regular water. Lift up the soda bottle and spray the seedlings on the soil.

If you have followed all of these steps this will give you the best chance of helping leggy seedlings to straighten and strengthen up. They will need support to do this because once their stems have bent over they won’t have the strength to grow up straight.

How to prevent leggy seedlings

Preventing seedlings from going leggy is the best option and now you know more about this problem you can stop this happening in the future. Here’s how to prevent leggy tomato seedlings.

1. Choose a bright position

When raising tomato seeds or young seedlings at home, positioning is the most important thing to consider to prevent leggy seedlings.

Whether you are growing them in a greenhouse or on your kitchen windowsill make sure your seedlings get around 6 hours of bright light. They don’t need direct sunlight but bright light throughout the day is best.

2. Good soil

Healthy seedlings will grow strong stems and soil is important to encourage good growth, Seeds should be raised in seed raising mix, sifted potting soil or a mix of coconut coir, potting soil and perlite. This will allow the seeds to grow well using the energy stored in the seed.

Once the tomato seedlings have grown to 3-4 inches high and have their second set of leaves they will be ready to plant out.

For more information, check out my article: When to transplant tomato seedlings

3. Fertilize when they are ready

Once the tomato seedlings have reached the 3-4 inch size and are ready to be planted out they will benefit from a boost of fertilizer to strengthen their leaves and stems. Plant them into good quality potting soil with added slow release fertilizer or improved garden soil.

When I plant my tomato seedlings out I like to dig in worm castings, aged cow manure and compost if I have it. I then will top on top the soil with a handful of pelleted chicken manure. This is slow release and contains a range of nutrients to support the tomato seedling.

Leggy Tomato Seedlings | Summary

Leggy tomato seedings can be a problem when raising seeds at home and is caused by low light levels. If you catch this problem early it can be corrected but the stems will need support. An empty soda (or water) bottle will hold the stems in place, just remember to remove the lid and cut the bottom off and it can fit over a small round pot.

Happy gardening.