Are the seedlings you have started indoors now quite tall, rather pale, and/or downright spindly? Are they even beginning to bend a bit, as if they might topple before they can grow the two sets of true leaves necessary for transplant? If so, they are what is known as “stretched” or “leggy,” and the culprit is insufficient light. Instead of sprouting new leaves, they grow taller because they are searching for light.
So what can you do?
The action you take depends on the type of seedlings you are growing. If they are tomatoes, you are in luck: there is a trick you can do at garden transplant time. You can actually set the seedlings almost horizontally into the soil, ever-so-gently inclining the very top of the stem upright, so that just a bit of stem remains aboveground. The buried stem will not only thrive, but will grow roots!
For most other seedlings, the best thing you can do is act quickly. You don’t want the seedlings to grow even a day taller. Get some small pots ready and transplant the seedlings from their current home into a new pot (see Handling Stretched Seedlings, below), burying their long, skinny stems as far up as you can. Water them in well, and get them under good strong light. If you don’t have grow lights, place them right under kitchen fluorescents or other strong indoor lighting — the leaves can be just an inch or so from the light. Or, better yet, move them outdoors — but only if the weather is mild enough for them to remain outside all day without freezing. You can bring them indoors for the first night or two, then let them remain outdoors until it’s time to transplant them into their permanent garden or container home.
Handling Stretched Seedlings
You already know that the long, pale, slender stems of your seedlings are weak. So when you move them from one location to another, be careful not to touch them. Handle the seedling by the plug, if it comes from a Bio Dome, or by the soil-and-root clump if started in a seed tray or peat pot. If you need to hold the seedling up as you gently add potting mix around it to bury the stem, grasp one of the cotyledons (the first, large leaves that open on the seedling) as gently as you can.
After carefully burying as much of the stem as you can in fresh potting soil, lightly water the seedling. You will want to sprinkle the water very gently around — not directly on top of — the seedling. This will cause the new potting soil to compact, and you can add a bit more to the top.
The Grow Light Difference
If you are starting seeds indoors in late winter, as most gardeners do, the most challenging issue you face is getting enough light. The winter sunlight filtering through your windows may not be strong enough to prevent stretching, and ordinary household lights are no better.
Under-the-counter kitchen fluorescents are often the best and most economical solution, because you can set the seedlings right under them (just an inch or two is ideal), then move them farther down as they grow. You can also lengthen the time the seedlings spend under the lights, mimicking the longer days of spring.
An even better alternative is plant grow lights. Unlike regular fluorescents, these offer wide-spectrum light, which is closest to natural sunlight. You can position your Bio Domes or seed trays right under the lights, tailoring the position and “day length” for the needs of each type of seed. And by using grow lights, you don’t have to light the whole room. You can even grow seedlings in a dark corner of the garage!
Grow lights are not cheap, but they can be the best investment you make in your seed garden. The bulbs last for years, and the results — healthy seedlings — are unbeatable.