What to Do With Leggy Bean Seedlings?

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If you’ve ever grown beans before, you know just how quickly the sprouts can start to emerge from the soil. But sometimes, this fast growth can quickly lead to leggy seedlings which are less than ideal for the life and health of your beans.

If your bean seedlings have gone leggy, then move them into some more light and turn down the heat mats. You should also make sure your seedlings are properly hardened off to strengthen their stems and that they’re pruned to encourage fuller growth.

I’ll go over all of these things in more detail and discuss why it might be in your favor to start a new round of bean seeds.

How to tell your beans have gone leggy

You’ll know that your beans have gone leggy because they will be really tall and lanky. They’ll have thin stems and won’t have that many leaves on them.

You may notice that your bean seedlings grow very quickly and can be as tall as 8 inches in just 2 weeks after starting your seeds. 

When seedlings become leggy and have weakened stems, they are at risk of falling over or breaking due to external forces like wind or rain. 

Once the stems of your beans break, there’s no saving them. So, it’s best to try to help them out early to keep this from happening. I’ll chat more about how to take care of your leggy seedlings later on.  

Why your beans are leggy

Leggy seedlings happen to the best of us gardeners and there’s probably a simple reason why it’s happened. Here are some of the main causes of legginess in bean seedlings.

Not enough light

Bean seedlings will grow leggy when they aren’t getting enough sunlight. To compensate for this lack of light, they will stretch their stems pretty far to reach any light possible. This is how you end up with tall and skinny stems. 

This is especially common in indoor growing spaces as light can be limited unless you have a good grow light setup. 

Too much heat

Grow mats or heat mats can be a great resource to help your seedlings germinate. But, once they’ve germinated, they tend to take off if the mats stay too warm. 

This can be especially true if you’re using heat mats in a room that is already heated. If your seedlings are warmed from every direction, they’re going to feel nice and comfortable and grow to be a bit wild and unruly. 

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How to treat leggy bean seedlings

Even if your seeds are leggy, don’t fret! There are still some measures you can take to save them. Most of the time, legginess has a simple solution. Here are some of them. 

Move them into the light

If it’s still too cold to move your seedlings outside, then try finding a window in your house that gets the most sunlight during the day.

For those living in the northern hemisphere, a south-facing window will give your seedlings the most amount of sunlight. If you live in the southern hemisphere, then you will want to find a north-facing window.

If you don’t have a well-windowed house, then consider investing in some grow lights so your seedlings don’t go without. 

Beans are also a great plant to direct seed into the garden as they can be quite hardy and grow very quickly. If your directly-seeded beans still seem to be leggy, then check to make sure you didn’t accidentally plant them in a shaded area.

Is the light being obstructed by something like a building or a trellis? If so, consider transplanting your bean sprouts to a new location in your garden where they’ll get better sunlight.

Turn off the heat

Although heat mats can be a great resource to help you get your bean seeds started, sometimes they can work a little too well and make your seedlings too warm, leading to legginess as I mentioned above.

If you notice legginess in your bean sprouts, then go ahead and turn those mats down if not off completely. 

If you’re starting your seeds inside a room that’s already heated, then you really don’t need the heat mats at all. I find that heat mats come in handy if I’m starting seeds in a room or greenhouse that’s only passively warmed by the sun but still gets a bit cold at night. 

Harden them off

Seedlings can sometimes become leggy because they get too comfortable inside and aren’t acclimated to the outside world. So, you need to harden them off. 

You should be doing this for almost all of your seedlings, not just beans. This will keep your seedlings from getting transplant shock when you plant them outside.

Hardening off seedlings is simple. All you need to do is move them outside for a couple of hours a day so they can get used to the outside temperatures and other environmental factors like wind or light.

After you’ve had them outside for about 6 hours, you can bring them back inside in the afternoon. Don’t put your seedlings outside on days that have exceptionally bad weather as they may not be able to handle it. 

You should start hardening off your bean seedlings about 1 week before you’re ready to put them in the ground outside.

Prune seedlings

It is possible to prune bean seedlings to help cut back some of that legginess. Pruning will also help your seedlings to start growing outward instead of just upward. 

For young seedlings, it’s best to snip or pinch off their growing tip as this will help to encourage fuller and bushier growth. Make sure not to cut so far back as to remove all of the leaves as this will ultimately kill your seedlings. 

Pruning beans can be hit or miss sometimes because the seedlings can be quite tall but only have two leaves attached. You don’t want to cut off the only leaves they have so it’s best to wait until they’ve developed some more. 

Start over

If it’s still early enough in the season and your leggy seedlings don’t seem to be getting better or growing more leaves to be pruned, then it might be best to simply start over. 

When you start your new seedlings, make sure you put them into direct sunlight or under good grow lights so that they’re not trying to stretch too far. If you’re using grow mats, check that they’re set to the lowest temp or even consider turning them off completely. 

I know it’s not ideal to have to start over with a new batch of seeds, but beans are great because they can germinate in as little as 7 days from planting. You’ll have new bean seedlings in no time.


Hopefully, by now, you’re feeling confident in your bean seedlings and are ready to take on any legginess they throw you.

Just make sure they have plenty of light, aren’t too warm from heat mats, and are properly hardened off. As an extra helpful measure, you can prune your beans to encourage outward growth instead of upward. 

And remember, there’s nothing wrong with starting over. A fresh start may be just what’s needed to get rid of any bean legginess. 

Check out these must-have gardening products

You don’t need much to start gardening, but some tools and products will make a difference in how comfortable and effective gardening can be for you. Here are my favorites:

  • Garden Trowel. A good garden trowel will last you many years. I love how sturdy this hand trowel from WOLF-Garten is, the metal doesn’t bend and it has a nice grip.
  • Trimming Scissors. I use them for delicate pruning and harvesting all summer long, and they’re super handy. These Teflon Trimming Scissors are extra nice because they don’t rust as easily.
  • Dutch Hoe. Dutch hoes may seem old-fashioned, but there’s nothing like a quick sweep through the topsoil to get rid of small weeds – no bending required. I love WOLF-Garten’s selection: this dutch hoe coupled with their universal handle.
  • Grow Lights. These grow lights from Mars Hydro are super strong, yet dimmable, so they fit every stage of growth. They don’t put out too much heat and are very economical.
  • Seedling Trays. There’s an art to choosing the best size for seedling trays so that it holds the perfect amount of water and gives the roots enough room to grow. These germination plugs are perfect when coupled with 1020 bottom trays
  • Liquid Fertilizer. You’ll need to feed your plants from the seedling stage, all the way to fruiting. This organic fish & seaweed blend is a very versatile option. Use it half-strength for young plants and full-strength for established plants.

Browse our list of tools, fertilizers & pesticides, indoor growing products and seed shop recommendations – we hope you find our selection useful and it saves you some time!

Ciara Konhaus

I’m Ciara and I’m a gardener and agricultural educator in zone 6b. I’ve farmed and gardened all over the Appalachian mountains and love to empower people with the tools they need to start their own gardens. There’s nothing more rewarding than growing your own food!

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