Seedlings in a tray may appear strong at first, but sometimes they begin to grow long, thin stems and smaller leaves, reaching toward the closest window. This “leggy” growth indicates that the seedlings are attempting to get better light. They have grown taller than they have grown sturdy, which could lead to issues when you eventually thin, pot up or transplant your seedlings.
The first thing to check is light. You need enough light to allow the seedlings to grow strongly. However, the amount of light they require varies by flower type. Your tray may be in the right place, but not the right distance from a sunny window to receive optimal light. Another sign of poor light is all of the seedlings leaning in the same direction. Relocating the tray or changing the light source will encourage more even growth. Turn the tray regularly if only one side is receiving good light, but don’t expect regular turning to overcome inadequate lighting.
You can do a quick experiment with a few seedlings. Place a few trays in different areas that receive different amounts of light. Keep the soil, watering routine and type of seeds the same. Check your seedlings at the same time each day and note any differences in leaf spacing, stem thickness, direction of growth, and emergence of true leaves. You’re not trying to prove anything; you just want to see how weak growth compares with stronger growth.
Crowding your seedlings can make the leggy growth worse. When seedlings are too close together, they compete for light and space. As they grow, they shade each other and their leaves overlap. Air flow around the seedlings decreases and they grow up and over each other. Once seedlings are large enough to thin, remove the extra seedlings according to the type of flowers you are growing. Spacing out your seedlings allows you to see them clearly and monitor soil moisture. They’ll also be ready to pot up or transplant later on.
Watering contributes to weak seedlings, but less water won’t cure bad lighting. Soil that is always wet can cause weak growth and poor root health. Test the soil before watering rather than keeping the seedling tray constantly wet. Small pots dry out quickly, but you don’t want your seedlings to wilt. Just ensure the soil isn’t overly wet. Proper drainage is key as seedling roots need oxygen as well as water.
Don’t try to strengthen your weak seedlings by giving them extra fertilizer. Fertilizer can’t make up for lack of light, and too much fertilizer may lead to weak growth and root damage.
Focus on light, thinning, watering and observation. When you thin or transplant your seedlings, hold them firmly by the leaves or root ball, and don’t squeeze or pull on the stem. Watch your seedlings closely and compare their recent growth to the leggy growth. If the newer leaves appear closer together on a stronger stem, you’re doing the right things.
