It's one of the most common issues you run into when starting plants from seed. What do you do when your seedlings grow skinny, delicate and spindly? This article can help diagnose why you are winding up with leggy seedlings and how to correct the problem.
What are leggy seedlings?
Leggy seedlings are those that become spindly, stretched and delicate instead of full and strong. These seedlings can be less vigorous and more prone to flopping over and failing to thrive. When these plants are transplanted later, they are likely to have problems. Stems that are too weak and thin can mean plants that are unable to stand up to outdoor weather conditions that include wind and rain.
Above: 'leggy' tomato seedlings. Seedlings are too tall and weak. White stems indicate lack of light.
Why do they occur?
The usual culprit for leggy seedlings is a lack of proper light. When seedlings are straining to get access to a light source, they can get tall too quickly reaching out for the light. But, this is not always the cause sometimes other factors can be to blame:
Poor soil conditions can cause seedlings to grow with slim and weak stems or when the soil is allowed to get too dry between waterings, it can keep the plants from leafing out as they should.
Temperatures that are too high can also lead to leggy seedlings. High temperatures cause a spurt of rapid growth in the stems, with leaves that fail to keep up.
Above: Seedlings straining for light by a window.
Can they be saved (and is it worth it)?
Disappointment can cause you to want to abandon weak seedlings and start over. But, it is often possible to correct the issues affecting your plants and get them moving toward stronger growth.
When light is the issue, changing the lighting conditions can often be all that is needed. Seedlings straining toward a window should be turned once daily so that the plants grow straight up and do not lean to one side. If there is simply not enough light for the plants overall, moving to a better lit area, such as a different window, an outdoor location or a greenhouse can remedy the issue.
Above: Brassica and tomato seedlings by a garage windowsill.
Moving plants to a cooler area can help if your seedlings are shooting up too quickly because of heat.
Sometimes, the issues that occur during the early seedling phases can be remedied when you transplant the seedlings to your garden. For instance when moving tomatoes, eggplant or peppers to the soil outside, plant them deeper than you normally would covering the majority of the stretched stem. This will encourage them to grow new roots along the buried part of the stem. This will not work for plants in most other families, however, as the stems may rot when buried too deep.
When determining whether to abandon or save leggy seedlings a few things to consider are:
-Do you have or can you get more seed?
-How much time have you already put into them? If it's only been a week since you sowed the seeds it is probably easier to just start again in better conditions. If it's been longer than a few weeks it's probably worth your while to try and save them, you've already invested your time and it would be a shame to have to start from scratch again.
-How leggy are they? If your seedlings are really leggy they may be too far gone and the chances of saving them may be slim. There is no harm in trying to save them but be realistic it may be smarter to start over.
How to avoid leggy seedlings in the future.
The best way to avoid leggy seedlings is to choose a position to start your seeds that will encourage the best growth. If you are using a window for lighting, choose a window that receives maximum light, if you don’t have an appropriate window consider other options like a mini greenhouse.
The use of an oscillating fan to gently blow the seedlings can help simulate windy conditions outdoors. This can spur the plants to form thicker, more resilient stems.
Be observant when growing seedlings; the sooner you notice something isn’t right the easier it will be to correct and by doing what you can to get the strongest seedlings from the start, you can be assured of the greatest level of success when you get your plants outside and into your garden.
Above: Healthy Brassica seedlings