Seedlings Getting Leggy? Here’s What to Do

February was a beautiful month here.  Lots of warm (for February) sunny days, bright blue skies, and nary a breeze.  Pruning the apple and nectarine trees was a pleasure.  I even started hauling bags of composted steer manure to their designated spots and breaking them open.  However, working them into the soil had to wait.  Apparently the ground was still frozen.  Still, the future boded well for happy gardening days in March.  (Remember, I’ve only been in this location for a little over a year.)

So far, this March has been a little disappointing.  I put the snowman dinner dishes that we use all winter away on March 1.  It’s been very cold.  We’ve gotten a little snow, but not as much as the weather forecasters said we would.  We’re giving them yet another chance to redeem themselves today, though they are already trying to weasel out again.  Yesterday they promised 2-4 inches for last night and another 2-4 for today.  We might have gotten an inch last night, and things aren’t looking so great for today.  We desperately need the snow, so I’m not complaining.  But if we aren’t going to get snow, then it would be nice if it could warm up enough to start planting.

Because, you know, there are a lot of little cabbage and broccoli plants needing to go in the ground.  They’re reaching that size.  And some of them are getting a bit leggy.

I’ve always put my tomato plants into the ground much deeper than the soil surface of the pot they were growing in—all those little hairs growing out from the stem will turn into roots and help the plant grow better and stronger.  I’ve also planted other vegetables deeper as well, especially peppers, and broccoli and cabbage when warranted.  And then I read something somewhere last year indicating that practice was an absolute no-no.  That they would not grow as well and they might even die. Oh, crud.

I’d never read that.  Apparently, my little seedlings didn’t either. 

So this week, as some of the cabbage and broccoli were getting a little leggy, I decided to research the matter fully. 

Why do seedlings become leggy?

Simply put, seedlings grow tall and thin, which we refer to as leggy (or spindly), when they are not getting enough light, as happens when growing them at a window instead of under grow lights.  Seedlings also become leggy when they are too far from the grow lights and/or there is no wind to prompt them to grow strong stems.  And some become leggy when there is too much nitrogen in their fertilizer, or when they are planted too densely and are competing for light and nutrients.

When are leggy broccoli and cabbage seedlings beyond hope of salvage?  If seedlings have black spots, have turned white, or have withered, they’re beyond help.  If not, you have a chance.

How is the problem remedied?  You’ve got several options here.

When starting seeds

When starting your seeds, make sure the grow lights are only 2-3” above the tops of the seeds or plants.  Raise the lights as the seedlings grow.  If you are using fluorescent bulbs, make sure they aren’t too old.  Even if they are still giving off light, older bulbs don’t give off enough.  Replace with fresh bulbs.

Water from the bottom.  While using a sprayer is good before the seeds germinate, bottom watering provides the moisture they really need.

Do not over-fertilize.  Fertilizer makes plants grow larger and faster, but not necessarily stronger.

Larger seedlings

Larger seedlings that are ready to go into the ground may be planted deeper so that less of the plant is above the ground. (Debate continues on this issue.)  Or a cardboard toilet paper tube, perhaps cut in half, depending on the size of the seedling, can be placed over and around the seedling to provide support and protection from wind.  The cardboard will disintegrate over the next few weeks as the seedling gains in strength.  This approach has the added benefit of protecting the seedling from cutworms.

If the leggy seedlings are outdoors, the problem is due to insufficient light and/or too much nitrogen and insufficient phosphorus.  To remedy these conditions, transplant the broccoli to a sunnier location.  Fertilize with a high-phosphorus, low nitrogen fertilizer and water it in well.

How else can you prevent the problem in the future?

Be the wind—brush your hands over the tops of the seedlings several times each day.  Alternatively, place a fan near the plants on the very lowest setting.  You want to create a gentle breeze, not a tornado.

Links to related posts:

Getting the Earliest Possible Crops 

Using Nasturtiums to Protect Cabbage and Broccoli 

References:

https://www.gardenguides.com/105870-grow-spinach-under-lights.html

https://www.hyanniscountrygarden.com/what-to-do-with-leggy-seedlings/

https://www.gardenbetty.com/leggy-seedlings-what-causes-them-and-how-to-correct-them/