cucumber seedlings growing tall and thin in front of my window

Fix Leggy Seedlings: 5 Best Ways

Most people who’ve grown seedlings have likely experienced their seedlings, seemingly overnight, growing too tall and thin to be able to hold themselves upright. That’s why knowing how to fix leggy seedlings is so important to indoor gardeners and outdoor gardeners alike.

What are the best ways to fix leggy seedlings? To fix leggy seedlings, space them further apart from one another, provide consistent moisture, reduce heat, and increase lighting.

In today’s guide, I’ll take you through each of the above fixes for leggy seedlings one by one and explain why each works. By the time you’re done reading, you’ll be ready to get your transplanted cutting on the mend!

5 Effective Ways to Fix Leggy Seedlings

1. Identify Legginess

Indoor veggies growing from seddlings in trays in my plant room
Not all tall and thin seedlings are leggy

In a plant’s seedling stage, it’s not always as easy to confirm if the plant has become leggy as it is when that same plant is more mature. 

That said, you can tell leggy seedlings apart from normal seedlings if you know what to look for, and that’s the first step to fixing them.

After all, you can’t fix a problem until you acknowledge it!

So what does a leggy seedling look like compared to a normal one? 

The first difference between the two is height. A leggy seedling might look like it’s sprouting up healthily, but what it’s really doing is trying to get more sunlight. 

A leggy seedling is a lot skinnier and lankier than the average healthy seedling. 

That’s not to say that a seedling has a ton of girth to it, but a leggy one will be even skinnier still.

That equates to weak seedlings. The fragility of the seedling means that too much sunlight or frost could be its death knell.

Finally, leggy seedlings don’t have the same rich, robust color as healthy seedlings. Rather than bright green, the seedlings will be yellow or very pale green. 

2. Put More Space Between the Seedlings

While some seedlings start as plant transplants or cuttings, others–appropriately enough–begin from seed. 

It’s the ones grown from seed that are at a higher risk of being leggy since you’re typically growing so many at once.

When you plant a seed garden, you’re usually recommended to place each seed X inches apart from one another. Failing to heed that warning means that when the seedlings develop, they’ll be very crowded.

There’s only so much light to go around. The seedlings feel like they have to crowd one another out, and so they begin growing tall, long, and skinny. 

In other words, they’re leggy. 

In the future, when you read that seeds should go at least an inch apart, or two inches, or whatever the recommendation is, it’s best to follow it. 

Each emerging plant will have the space to grow and develop leaves. The seedlings won’t feel starved for light or resources either. 

3. Provide More Consistent Moisture

When propagating some plants, you’re supposed to keep the soil moist. 

Since there’s not a lot of soil to go around, it’s important that the soil is never soaking. 

Using a spray bottle to mist the soil around the base of the seedlings to nurture the seedlings as well as add a bit of humidity can go a long way to growing healthy seedlings.

Providing consistent moisture while nurturing them with water every 2 to 3 days can prevent the seedlings from becoming leggy.

It’s just as critical that the soil never dries out, especially for some growing seedling species.

When a seedling has inconsistent water, it’s not going to grow properly.

Plants use water to send nutrients to the soil, which can reach the growing root system. Without water, those nutrients can’t spread.

The stems of the seedling will be weak and breakable. The leaves will be sporadic. 

The worst part is that if you continue to make a habit of this on-again, off-again watering schedule, the weak seedling will likely die. 

If you have a hard time remembering to moisten the seedling’s soil, set an egg timer.

You can also rely on your smartphone to make you better at watering your plants. 

You can set reminders on your phone or download an app that will alert you when it’s watering time. 

4. Lower the Heat

If your seedling is growing into a plant species that you already know and love, you can’t provide the same degree of heat to the seedling as you do to the full-grown plant.

Providing too much heat is a sure way to turn your healthy seedlings into leggy seedlings.

Well, if your plants survive at all. They could also burn to a crisp. You already know that a seedling is young and fragile.

How do you prevent this terrible outcome? 

For starters, watch your temperatures. Seedlings, no matter the species, usually prefer one consistent temperature range.

That range is 65 to 75 degrees Fahrenheit.

Whether you’re growing the seedlings at home or at work, never let the temperatures exceed 75 degrees.

Be sure to check for other sources of hot air. For example, if your seedlings are growing on a windowsill, a drafty window in the summertime will let in plenty of warmth.

Your seedlings should not be in the path of a radiator, nor should they go near a refrigerator. 

Yes, that’s right, your fridge produces more heat than you would think.

It’s not only the temperature you have to watch out for, but the humidity as well.

Indoor gardeners usually create humid conditions for seedlings in one of two ways. 

You can buy a humidity dome, which is a plant tray lid, or you can use the plastic zippy bag method.

With the plastic zippy bag method, all you do is take a clean zippy bag, open it up, and place it over the plant. 

The air within the plastic zippy bag gets nice and humid. 

Even if your humidity dome is completely transparent, you’re not supposed to leave it on forever. The same goes for a plastic zippy bag. 

You want to remove these items after a couple of hours and certainly before you go to bed for the night.

5. Increase the Lighting 

I saved what is by far the most common reason that seedlings get leggy for last, and that’s a lack of sufficient lighting. 

Legginess is often a seedling growing towards the light. When a plant matures and becomes leggy, it’s doing the same thing. 

Even if that light is dim or far away, the plant grows towards it.

If your seedling is on a windowsill, while it’s getting some sunlight, it might not be enough to sustain its growth. 

What you should do in this case is use a grow light to add additional light to ensure your seedling does not become deficient in light and begin leaning and chasing the light.

Now, I know what you’re going to say, isn’t artificial light not as good compared to sunlight?

Not to your seedling! Seedlings–and mature plants, for that matter–think that light is light. 

Seedlings can’t tell the difference between the sun and an artificial grow light, so it doesn’t matter which you use. 

You can place the grow lights right over the seedlings according to the instructions included with your lights. 

If you suspend the grow lights too high, your seedlings can still end up leggy.

Then, turn the grow lights on for at least 12 hours but really somewhere along the lines of 14 to 16 hours. 

For the remaining eight hours, the seedling should be in a dark environment.

You don’t have to manually turn the lights on and off yourself, of course. You can always use a timer to do it. 

Can You Bury the Stems of Leggy Seedlings?

Now that you’ve begun correcting the care mistakes of your leggy seedlings, the seedlings won’t automatically become less leggy overnight. 

It would be great if it worked that way, but it doesn’t. 

What some indoor gardeners do, and what I often end up doing as well, is bury the long stems of your leggy plant deeper in the potting soil.

However, you have to time it right. If your seedlings are still very weak when you bury them, and especially if the soil is damp, then the plant will likely rot and soon after, it will die.

You should let at least several weeks transpire, all the while maintaining proper care of the seedlings. This will allow the seedlings to regain their strength and begin growing a little more normally.

I’d also suggest hardening off the seedlings, which will increase their resilience and strength even further. 

Although hardening off is a method used to transport indoor plants outdoors, you can still do it and keep your seedlings indoors. 

The hardening-off process begins shortly after germination, maybe two weeks after. 

Introduce an oscillating fan into the seedlings’ environment and run it on low for a few hours each day.

As the air hits the seedlings, the stems will bend and wiggle, forcing the seedling to build stronger stems in response. 

Once the seedling stems are noticeably thicker and more durable, now it’s time to bury them deeper in the soil.  

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