Leggy seedlings are one of the most common frustrations for UK gardeners—especially during late winter and early spring when light levels are low and everyone’s eager to get sowing. But what causes seedlings to become leggy? Is it really a problem? And most importantly—how can you prevent it?
In this guide, we’ll cover what causes leggy seedlings, how to fix them, and how to avoid the issue altogether so your young plants get the strong, healthy start they need.
Leggy seedlings are those that grow tall, thin, and stretched out—with a long stem and very few leaves. They often look weak or floppy, leaning toward any source of light.
They’re easy to spot: the stem is too long for the size of the plant, and the seedling may bend, fall over, or look pale and straggly.
Most of the time, it’s a combination of too little light and too much warmth—common in early spring indoor sowing.
Yes and no:
Bottom line: It's best to prevent it in the first place.
Caught it early? You might still save them:
Yes—especially if sowing anything before March.
Even a simple grow light is far better than relying on weak windowsill daylight in early spring.
Leggy seedlings are a sign your young plants aren't getting the right balance of light, temperature, and space. It’s one of the most common beginner mistakes, but easily corrected once you know the signs.