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Why Do My Seedlings Get Leggy? Stop Them In Their Tracks!

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Gardening with low-quality seedlings can be frustrating when you have leggy, spindly seedlings. When the stem or internode of a seedling grows thin and long, this makes them fragile, harder to transplant, less likely to thrive and can result in the loss of your plants, wild heads of greens that do affect the harvests, when you are growing your own food.

Why do seedlings get leggy? There are a number of reasons seedlings get leggy. But the most likely is lack of light. The seedling is in the growth phase and is searching for a better light source. It is important to provide adequate light levels at the right range and spacing when your seedling germinates.

The Advantages Of Starting Seedlings

The advantage of indoor seed-starting cannot be denied. For one, it gives you complete control over the varieties and types of crops you grow. It also gives you control in terms of how the plants get produced. However, growing indoor seedlings does come with maintenance. They are not unlike babies in which everything has to be just right. Without the right conditions, seedlings develop small leaves, pale stalks and grow thin and long instead of stout and robust.

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Leggy Seedlings Equals Weak Seedlings

The weak stems can’t hold themselves up. Basically, they look like they are striving to grow because they are. Not only do they look unsightly, but this also means that when transplanted, they are also unlikely to survive the outdoors. Legginess means the seedlings aren’t storing as many carbohydrates. If you have plants not getting sufficient sunshine or light levels if indoors, they won’t be able to deal with the rigors of wind and sun.

Getting A Jump Start With Seedlings

Many serious vegetable gardeners start seed indoors to get a jump start on the season for growing. In cold climates, starting seeds indoors is an assurance that squash, zucchini, cucumbers, tomatoes, and other slow-maturing plants will produce fruit by midsummer. For flower gardening, this works too. Purchasing seeds of flowers is one practical alternative to buying younger annuals and perennials.

The Challenge Of Growing Seedlings

The only thing is that sometimes, starting seeds indoors can be fraught with challenges. The most common of which is that the seedlings turn out leggy. Even carefully sown seeds in the right soil, precisely watered, placed in a window that faces south, diligently watched until germination and sprouting falls victim to spindly, weak stalks sometimes. Legginess is a pattern of irregular growth.

This is brought on by low light levels indoors. Even when in south-facing windows. Levels of light are short during the winter months when most gardeners are starting their seed sowing. This can have detrimental effects on your seedlings if inadequate light levels are present.

This is not exactly healthy for your plants as they grow larger. The reason is that being leggy will make it unable to support its weight. Also, once exposed to the elements outdoors, leggy seedlings face a great challenge. Make sure your conditions indoors create plants that are well-established so they thrive well in a garden setting. This way, when you go ahead and transplant them outside, they grow properly and with stability.

What Makes Seedlings Get Leggy?

Traditionally, legginess is caused by a lack of sunlight or light. When light is either indirect or too week to meet the needs of the plant, what happens is that the stems grow thinly because the plant reaches its leaves towards the light desperately. Seeds that start when the sun is low in the sky, such as in early spring or later winter are prone to this pattern of growth. Sunlight in these seasons isn’t strong enough to allow plants to grow, let alone thrive.

Prevention of Leggy Seedlings

To prevent seedlings from getting leggy, there are a few surefire methods that are known to work. Here is a list that ensures you never have to transplant leggy seedlings at all.

  • Adjust Your Light Source When Seedlings Get Leggy
  • Use Artificial Light When Seedlings Get Leggy
  • Give Your Seedlings Direct Light
  • Remove the Competition When Seedlings Get Leggy
  • Seedlings Get Leggy From Overheating
  • Seedlings Get Leggy When There Is Not Enough Water
  • Check the Soil Ammonia Nitrogen Content
  • Thigmotropism

Adjust Your Light Source When Seedlings Get Leggy

Remember to keep your source of light close enough to your seedlings so that they never have to reach out to get it. Make sure not to cause the leaves to burn by keeping artificial light two to three inches from the top of your seedlings. If you place artificial light any further than three inches the tiny plants tend to stretch themselves, which results in becoming leggy.

Use Artificial Light When Seedlings Get Leggy

Providing artificial light. If there is no window anywhere near which provides direct light for seven to nine hours, you can use artificial lighting. Various grow lights specially made for growing seedlings are available at plant stores.

Of course, a regular fluorescent shop light fittings with T5 bulbs will do the trick, as well. Use artificial light to provide a minimum of sixteen hours of light on your seedlings daily. Get a timer to make tracking exposure time easier without any extra effort on your part.

These days lighting technology has moved on in leaps and bounds. LED has made massive advances in providing the correct light levels for seedlings at very affordable costs. I recently produced a video on one such unit that I absolutely love.

LED makes lighting so much easier and very economic on your energy bills. This unit is awesome for providing the light you require and stops leggy seedlings. The Spiderfarmer SF1000 available on Amazon is perfect for this task. You can see that video below.

Give Your Seedlings Direct Light

To prevent leggy seedlings, you will need to provide light directly. Just because it seems as if a window seems bright from morning till sunset does not automatically mean that there is direct sunlight created for growing plants. You need to place seedlings by a window that experiences seven to nine hours of sunlight directly per day. Even outdoor plants that thrive in partial shade during summertime need sunlight directly for seedling propagation.

When there are sets of leaves on the seedlings, this indicates that they have a root system and have established themselves. Pinch off the top sets of leaves to train them to bush and to keep the plants compact. This will allow the stalk to thicken up and make for a much stronger plant.

Remove the Competition When Seedlings Get Leggy

When many seedlings grow together, they get big enough at a certain stage to begin shading each other. This forces them to compete for light and grow taller as a result. Rather than letting them get unnecessarily tall, adding light and transplanting each seedling at the right time when their actual leaves make an appearance is a solution.

If a particular seedling crop gets larger and begins to shade the others before transplanting day arrives, you might want to consider using larger seedling trays and plugs to give each seedling more space.

Seedlings Get Leggy From Overheating

When seedlings overheat, this could cause a rapid spurt of growth that leads to becoming leggy. Germination requires warm temperatures. However, most seeds grow optimally at a temperature of sixty-five degrees Fahrenheit or around nineteen degrees Celcius in the daytime and at fifty-five degrees Fahrenheit thirteen degrees Celcius at night. If you use a heat lamp and didn’t realize it was too hot, the stems will grow faster than the leaves.

Seedlings Get Leggy When There Is Not Enough Water

Legginess can also be a symptom of not getting enough water. The same can be said for improper drainage and poor soil, which stunts seedling growth as they struggle to absorb the necessary nutrients and water. Make sure you are watering your seedlings the appropriate amounts they need for proper growth. Aim for damp soil not moist. Water from the bottom is also much better for seedlings.

While we are talking about water, it is much safer to use tap water with seedlings, as opposed to rain or well water. This will ensure no bacteria or fungus can cause issues at such a fragile stage of the plants’ life.

Check the Soil Ammonia Nitrogen Content

Using different mixes of fertilizer results in ammoniacal nitrogen in varying amounts versus nitrate nitrogen. The plant uses nitrogen in the form of nitrates directly. This results in growth that is more compact. On the other hand, ammoniacal nitrogen produces leggy seedlings.

Fertilizers used in hydroponics hardly have any ammoniacal nitrogen since these are created to be available immediately to crops. If you are using a fertilizer you grabbed off the shelf and this was designed for farming or soil gardening, the urea contributes to the nitrogen. Switch instead to fertilizers for hydroponics. Check the label and make sure there is no ammoniacal nitrogen content or urea.


 Strengthen your stems through thigmotropism. This means stimulated the movement of environmental stress on your seedlings. In other words, you need to mimic what goes on outside right on your kitchen table. You can do this by putting a small fan beside your seedlings and time the simulation of your plants being blown in the breeze a few hours daily.

If you don’t have a fan or want to reduce energy, you can also stimulate stronger growth by passing your hand over the seedling tops a few times each day. This will help the stems of each seedling become stronger and ready for the outdoors.

Preparing The Seedlings For Outdoors

One common beginner mistake many newbies make is sowing tender seedlings that have been grown indoors directly into the garden as soon as the date recommended for planting arrives. This can be disastrous as the sudden environmental change can kill seedlings that have not been acclimated. To keep your seedlings alive, start by hardening them off before the date for transplanting arrives.

To do this, move them outdoors for a few hours daily when there are light breezes and mild temperatures. At night, bring them back indoors to protect them from the cold night air. Gradually increase the amount of time they stay outside during the day. By the time planting time arrives, the seedlings will be tough enough for surviving any weather inconsistency

Can You Save Leggy Seedlings At Home?

Dependant on the seedlings and their varieties you can save some seedlings if they get leggy. Others maybe have to be consigned to the compost heap. Seedling that can recover from being leggy are:

  • Any of the brassica Family
  • Tomatoes
  • Melons
  • Pumpkins / Gourds. Squash

All of the above seedlings can be transplanted much deeper even right up to the cotyledon leaves (Seed Leaves). This starts the process over giving you a very short plant. You can do this because these plants can either root from the stem, or do not have problems with stems being buried. Be mindful of what seedlings you try this with thought, as some seedlings will rot off if you bury them deeper.

Know When To Let Go When Seedlings Get Leggy

For gardeners, it can be heartbreaking to cut their losses when it comes to extremely leggy seedlings. This is particularly true when they have become somewhat emotionally attached to their baby plants and did not expect to see their seedlings get leggy. The thing is, when they get too skinny, they really won’t do well outside anyway. You will just need to start over with new seedlings using the above guidelines.

When seedlings get leggy, you can’t create an un-leggy plant once they have grown past a certain point. The best thing you can do as a last resort would be to plant more seeds in a location that is full of sunshine. You can tell when your seedlings have passed the point of no returning. Whey they are sort of leaning over and are quite limp, they are usually past the point of being savable. This is when you need to let go and start over with a new batch.


Although it sounds complicated growing seedlings, it is well worth the effort. It allows you to get good yields of food or flowers from plants we wouldn’t normally have a long enough season to grow. By following the tips I have given you above leggy seedlings should become a thing of the past for you. Now you know these rules you can get this season off to a great start with no worries.

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And remember folks, You Reap What You Sow!