5 BIG Causes of Leggy Plants [& How To Fix Them]

By: Chenell - Lead Writer and Gardening Advocate

Growing plants indoors is one of the most fun activities once spring is nearing, but it can also come with a lot of problems. It can be exciting to see plants grow quickly, but then get a little scary when you see your plants falling over.

What are Leggy Plants? What Do They Look Like?

Even if you try your best, you still might end up with leggy seedlings (i.e. your plants are falling over). I bought all the right equipment, but didn’t realize that you needed to remove plants from the heat mat once they sprouted. I just thought they stayed on there until it was warm enough to harden them off outside.

So then I ended up with these leggy onion seedlings:

leggy seedlings


As you can see, leggy seedlings are seedlings that are stretching and falling over.

If you sowed your seeds a few days ago and they’re already 3 inches tall, that’s NOT a good thing. A rapid growth spurt is an indicator that your plants likely have fragile stems and are lacking something they needed to grow stronger stems and roots.

They might need more light, more water, or more heat. Or maybe they have too much heat.

Can Leggy Seedlings Recover?

I know the first thing you’re thinking is, can I even salvage this situation?!

Yes, kind of. It depends on how long they have been “leggy”. You’ll need to change up their environment a bit as soon as possible.

The first thing to check is how warm the environment they are in is. If it’s 55 degrees or lower, you’re going to want to get some heat in there pretty quickly. In addition, if they aren’t getting enough light, you might need to add some artificial light.

Some plants stretch up to try and get more light, while others are just growing on overdrive because the conditions are so hot.

Main Causes & How to Fix a Leggy Plant

First, let’s check out some of the causes of leggy seedlings so we can decide how to fix them.

1. Lack of Light

Are your indoor plants getting enough light? This is one of the main causes of a leggy plant.

You can use a light meter like this one to help determine if your indoor plant needs more light. If they’re not getting sufficient light, try moving your seedlings closer to the light. Some plants will stretch to get enough light if they aren’t getting enough, thus the legginess.

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02/18/2024 11:44 pm GMT

If they aren’t getting enough light, you should move them to another area of the house to try and fix this problem. Most plants need at least 6-8 hours of direct sunlight to grow. This generally is NOT what they get on the kitchen windowsill, even if it’s a south facing window.

You might need to get some grow lights to supplement the natural light they are receiving.

I had this problem with my onion seeds and I just needed to lower the light to bring it closer to the plant so they weren’t stretching to reach it.

Plants can’t really get too much light, so more is always better (but you don’t need to go overboard and spend a ton of money on lights either). Of course, you don’t want to leave the lights on for a full 24 hours either.

grow lights leggy plants

2. Too Much Heat

This could absolutely be the cause of your leggy seedlings.

If you’re using a heat mat, make sure you are removing plants from the heat mat once they sprout. If you leave them on too long they can start to rot and fall over.

Too much heat is generally the issue here. If you’re not giving your plants enough heat, they will grow really slow or take a long time to germinate.

If you’re using humidity domes, go ahead and remove those from your seed trays to avoid overheating your seedlings.

3. Not Enough Water

The next thing to check is the amount of water your plants are getting. If they aren’t getting enough, try using a mister spray bottle to supplement. You can also use the bottom watering technique to make sure they are receiving enough.

It stalls plant growth when the soil is too dry, especially as the seeds are still developing and not yet turning into seedlings.

While this usually isn’t the cause of a leggy seedling, I wanted to include it in case that is what’s happening.

4. Overcrowding

“Hey, can’t I get a little space around here?!”

If you grow your seedlings too close together, they might be causing one of the 3 problems above. Some of the plants might be blocking the light from others, and they are immediately in a race to the top to get enough light.

If you’re going to plant multiple seeds closeby, make sure you are thinning out your seeds once they start sprouting leaves.

5. Lack of Air Flow

Another common cause of legginess is not enough air flow. Always, always, always make sure you are blowing a fan around your seedlings. This helps make sure they get enough oxygen, but also helps them grow stronger stems because they’re constantly being blown around.

These are the fans I get that hang from the sides of the shelves in my grow room.

AC Infinity MULTIFAN S3 - Ultra Quiet USB Fan

These fans come with regular plug as well, and can be daisy chained together for aerating more space. They're very quiet, but provide a good amount of air circulation.

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Yes, they are computer fans meant to cool down modems, but they work wonders at keeping the air flow constant.

You can also use a house fan, box fan, or anything that moves air around constantly.

Remember: Light, Heat, and Water

You can prevent most problems with leggy seedlings and grow a healthy plant by keeping those three things in check.

If your seedlings are already tall and spindly, and you’re already into the season, it might be better to just start fresh and try again.

Fixing these once they’re already tall is hard work, and sometimes not possible, so you might want to cut your losses and try again instead of wasting more time trying to get the conditions perfect.



Hi - I'm Chenell! I lived in the city for almost a decade, but after moving to the suburbs in 2020, I decided the logical millennial thing to do was to learn how to grow my own avocado toast. That's what this site is all about. 🥑

You can get access to all of my free resources and get some epic dad jokes (and helpful gardening stuff) emailed to you each week by signing up here.

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