The fact that leggy seedlings aren’t bad but they aren’t ideal, either. The taller they become, the weaker, thinner, and more fragile they will be.
Therefore, you should find ways to fix the problem as soon as possible or to avoid it.
In this article, we’re going to walk you through our tried-and-true backs to fix and prevent leggy seedlings. Let’s get started!
How To Fix Leggy Seedlings
Make Them Mighty
Thin Your Seedlings
This is the very first thing you need to do!
Thinning down leggy seedlings help decrease competition for water, light, space, and nutrients, along with improving air circulation. After sprouting, you should frequently remove unwanted sprouts to finally reach the ideal density which is one sprout/container or one sprout/cell.
Trim them out; don’t pull or pluck them.
Start applying fertilizer on your leggy seedlings once they are several weeks old or until they develop the 1st or 2nd sets of true leaves.
We highly recommend using liquid fertilizer and always dilute it following the manufacturer’s instructions (found on the product package). When it comes to liquid fertilizer for seedlings, there are two common options: fish emulsion and seaweed extract.
The biggest difference between them is that fish emulsion is more like a liquid fertilizer while seaweed extract is referred to as a plant tonic.
We personally love seaweed extract because it contains numerous nutrients with low-content phosphorus and nitrogen.
How do you apply fertilizers to seedlings?
Since leggy seedlings are very weak, you should feed them properly.
Avoid pouring fertilizer or water top down as it doesn’t distribute moisture or nutrients evenly while your seedlings are riskily knocked over.
The best way is to add fertilizer/water into the lower tray that your seedling trays are placed on.
It prevents all the problems stated above while encouraging seedlings to develop deeper roots.
Add Light Air Circulation
An effective way to strengthen the stems of your leggy seedlings is to tickle them with your hands or use an oscillating fan (at a low speed setting) instead if you don’t have such much time.
Gentle air circulation helps seedlings to shake and move, therefore, encouraging their stems to develop stronger and tougher.
Introduce outdoor environment to seedlings
This extra step is especially for indoor seedlings to help harden them off before they’re officially transplanted outside.
Repeat taking your seedlings outside daily in a week. On the first day, place them in a shady spot outdoors and leave for a few hours. Gradually level up the time and the hours of sunlight exposure in the next few days.
Turn Down (Or Off) The Heat Mats
Heat mats are commonly used during winter by those gardeners who want to start seeds indoors. They provide seeds with enough warmth for faster germination speeds.
But too much warmth is prone to make seedlings leggy.
If it did happen in your case, turn down (or off) all the heat mats while giving the seedlings more light.
How to provide more light for indoor seedlings?
If you have not used a supplemental grow light yet, add one or more depending on the scale of your seedlings.
Make sure to provide stronger light by changing the grow light’s illumination settings or lowering it closer to your seedlings.
Still, make sure the light isn’t too close to burn the leaves.
How To Prevent Leggy Seedlings
Below are some tried-and-true hacks to prevent leggy seedlings:
Keep An Eye On Heat Mats When Using Them
As stated above, leggy seedlings easily happen if the seeds are provided with warmth for too long. Therefore, if you are going to use heat mats, make sure to check and control the temperature regularly.
For busy gardeners, a heat mat designed with a temperature probe and thermostat control will make things a lot easier.
After sprouting, set them to only turn on when the soil temperature is under 65 degrees F.
Make Sure To Provide Enough Light To Your Indoor Seedlings
The ideal amount of lighting for young sprouts is 12-16 hours a day.
To do that, you can place your seedlings in a south-facing window if available or install a grow light at 2.5”-3” above them.
A trick for those gardeners who plan to grow lights, choose ones that come with adjustable strings or chains so that you can easily adjust their height during installation and during use.
Always keep the distance between grow lights and your seedlings at 2.5”-3”.
Don’t hang the lights too high because seedlings are prone to be leggy but don’t keep them too close to the plant as their leaves might be burnt because of overheating.
Besides, a grow light built with a timer is better in controlling the lighting time.
For Seeds That Are Sowed Outdoors
In this case, you should choose a sunny spot to sow them. But only sow seeds outdoors from spring to autumn because the daylight hours are still long enough for happy seedlings.
Avoid sowing seeds in the winter as well as avoid those places that are fully or partially shady.
Remove Covers Over Your Seedlings
After the seedlings sprout, remove any cover (including transparent covers) above them to ensure they’ll receive enough lighting.
Above are all the tried-and-true hacks to fix and prevent leggy seedlings that our team would like to share. Hopefully, they were helpful to you.
The sooner the problem is found, the easier it is to fix.
In bad cases that leggy seedlings are detected too late after germination, keep them as a “lesson” for later and start fresh over if you have ample seeds. Take it easy and always tell yourself that failure teaches success.