How to Save Leggy Tomato Seedlings? (Solved)


Picture of leggy tomato seedlings

It takes a lot of time and effort to get the right soil, climate, ecological, and geological conditions for your crop. And when the time comes to reap the benefits, it turns out to be a damp squib. No gardener would like the sight of thin, pale, fragile, and stretched-out stems.

It is the very indication that the plant is starving. There are quite a few culprits for those leggy tomato seedlings. And to get your seedlings back to shape, you need to identify those culprits and fix them.

Save leggy tomato seedlings by planting right up to the cotyledon leaves when potting on. Then identify what caused it. Common factors responsible are lack of light after germination, inconsistent soil moisture, overcrowding, and poor ventilation. Resolve these issues after potting on to ensure strong future growth.

Depending on the cause, you will determine the plan of action. So, let us know more about all the factors one by one and talk about ways in which you can fix them so that your seedlings grow stronger and healthier.

How to Identify Leggy Seedlings?

If you observe your seedlings have grown too tall and skinny, they can be described as leggy. They may even be pale and yellow. They would also not be quite bushy. In the gardening world, tall does not indicate health. Seedlings that are thick and stocky are considered to be healthy.

Beginners might have some trouble identifying leggy seedlings, but with time they will get better. Also, leggy seedlings are quite common and can be saved easily, so do not worry.

What Causes Leggy Seedlings?

Lack of Light When Sowing Tomato Seed

Tomato plants need more than 10 hours of direct sunlight in a day to grow properly. So, seeds that are sown too early before the last frost and/or started indoors can result in leggy tomato seedlings. The seedlings would bend in the direction of the sun or stretch out to reach the source of light.

Overcrowding Tomato Seedlings in The Tray

If lighting is not the issue, crowding might be. It also usually prevents the seedlings from getting sufficient light. When the plants are too closely located, the shade of each plant will overpower the available light.

leggy tomato seedlings

Using Excessive Tomato Fertilizer

Too much fertilizer in the soil can also result in leggy seedlings. It is important to ensure that your plants get the right balance of nutrients. Too much nitrogen or any other nutrient can overdrive, producing only foliage and no blooms.

Too High A Temperature Can Cause Leggy Tomato Seedlings

Heat is good for the growth of seedlings, but a setting that offers more heat than is required will cause a burst of growth, leading to spindly seedlings. Usually, seedlings grow best at 15 to 21 degrees Celsius. 

Poor Ventilation Can Make for Weak Tomato Seedlings

If you are raising your seedlings indoors or in a protected environment, the chances are that they are not getting sufficient air. Since seedlings planted outdoor are prone to airflow and winds, they become stronger, and their stems grow thicker. Thus, the lack of proper airflow can make the seedlings weak and fragile.

Tomato Seedlings Hate Dry Soil

Lack of moisture in the soil can prevent the seedlings from getting the required nutrients from the soil. Other than inconsistent watering, improper drainage can also be a cause of dry soil. This can stunt the growth of the seedlings.

What Are Some Other Mistakes That Result in Leggy Seedlings?

Choosing The Wrong Tomato Seeds

A large number of seeds are sprayed with fungicides. This is to stop rodents and insects from infecting the seeds. One should pick seeds carefully and look for words like – ‘certified,’ ‘organic,’ and ‘non-GMO.’

Starting Tomato Seeds Too Early or Too Late

Timing plays an important role while sowing seeds. Sowing them early is one of the biggest mistakes that gardeners make. This is because the soil temperature should neither be too hot or too cold for successful germination. To know the right time, you need to know your area’s average last frost date.

From that date, all you need is to count backward the number of weeks required for seeds to be ready for transplant. The time you get is exactly when you should be planting.

How to Fix These Issues?

Providing Sufficient Light For Tomato Seedlings

leggy seedlings under lights

To ensure that your seedlings get enough light, you need to place the pot directly under the sun. You need to aim for about 10 to 12 hours of direct sunlight, so placing them on the windowsill would not work. If you are raising them indoors, you can use grow lights as well.

Maintaining Adequate Soil Moisture For Tomatoes

Consistent watering is the key here. Be sure that the soil is evenly damp and can retain moisture. Also, the soil should not be too sandy that drains faster. You can use potting soil or seedling starting mix.

Sowing Tomato Seeds Thinly

It would help if you sowed the seeds far apart from each other. If that is what you have missed out on, you can still re-pot them in different or larger pots. You do not want the seedlings to compete with each other in search of nutrients, light, and air.

Diluting Tomato Fertilizer

Tomato seedlings should get fertilizer once they have developed their second set of leaves. Also, they should only get about one-quarter to one-half strength of the dose suggested on the product. Since the current nutrient content of your soil also plays a major role, it is better to get your soil tested before you begin fertilizing.

Maintaining Optimum Temperature When Growing Tomatoes

While the seedlings need a warm setting, the temperature should not go beyond 21 degrees Celsius during the daytime and 15 degree Celsius during the nighttime. Also, remove the humidity domes from your seedling trays or take them off the heating mats after a couple of days of sprouting.

Ensuring Proper Airflow For Tomato Seedlings

By ensuring that each seedling is planted far apart, you can improve the airflow. However, if they are indoors, you can use an oscillating fan that can mimic natural winds. Or you can even brush your seedlings.

Also, to help your seedlings grow stronger, you need to re-pot the plant and bury them deep down. You would need a large pot to help the roots grow.

How to Brush the Tomato Seedlings?

To re-create the effect of natural winds, you can brush a folded piece of paper across the tops of the seedlings, or just tapping them will help stimulate growth and help them grow into thicker and stronger seedlings. You can repeat this twice a day for around a minute.

What is Transplanting or Replanting?

strong healthy seedlings

Transplanting, also known as replicating, removes a plant from one location and resets it on another. If it is carried out well, it will ensure that the plant has an increased survival rate and decreased disease incidence.

While transplanting seedlings, you need to get rid of any waterlogged or diseased soil. It would help if you also trimmed back roots that have rotted.

What is Hardening Off Plants?

Hardening off plants is the process of exposing tender plants to sunlight, wind, and inconsistent temperatures steadily to help them get acclimated. This is usually done before seedlings that started indoors are ready to be moved to the garden. This process will help in reducing the transplant shock.

How to Pinch Back the Seedlings?

Use your fingertips or a small pair of scissors or pruners to snip off the top of the seedling’s stem. This has to be done right above the point where a leaf or set of leaves connect. It would help if you did not pinch right on the point where the leaves connect. This would remove the bud that will become a new branch. So, be sure that aim for slightly above that point.

When to Pinch the Seedlings?

It would help if you waited until the seedling has grown a few sets of true leaves. This would not count the cotyledons or seed leaves that appeared when it first sprouted. When the seedling is around 4 to 6 inches tall, pinching them back will help them grow healthier and bushier.

When Should I Give up on Leggy Seedlings?

If your seedlings are limp and falling over is better that you do not put in your time and effort trying to save them. It would be best to look for the distance between the soil and the first set of leaves. If it is more than a couple of inches, you should chuck them. The same goes if the gap between the leaves is an inch or more.

We know that it might break your heart to give up on your little seedlings. But sometimes, it is just better to start over. But this time, you need to be sure that you provide them with ideal conditions and keep a check on them. You can save leggy seedlings if they are caught early.

Even some of the most experienced growers might come across leggy tomato seedlings. But by putting some efforts in the right direction, you can help your seedlings grow stronger and turn into fruit-bearing plants. This information will help you ensure that your tomato seedlings thrive and grow up to bear juicy and luscious fruit.

Conclusion on How to Save Leggy Tomato Seedlings

You do not have to worry if your tomato seedlings get leggy. They can be saved thanks to the hairy stems of tomatoes. These hairs will take all root when buried in compost or soil. Plant them deep and provide adequate lighting. Artificial lighting may be required during the early part of spring. You can do it; follow this guide and other articles to ensure you get a great crop.

For more growing advice consider downloading my FREE tomato growing eBook.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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