Troubleshooting Common Seed-Starting Problems

Problem #1: Seedlings are “Leggy.”
Leggy seedlings happen to the best of us. “Leggy” means that the stem is very long between the ground and the first set of leaves. Often leggy seedlings tip over; they’re not strong enough to hold themselves up.

Legginess happens because seedlings are streeeeeeeeeetching desperately toward the light. It’s a clear signal that they are not getting enough bright, direct light. Rather than grow leaves, they’re putting all of their energy into finding a sunbeam they can soak up.

Some leggy seedlings can be saved— tomatoes, broccoli, cauliflower, cabbage. Leggy seedlings that are a lost cause will let you know; sadly, they will not have the strength to go on.

Prevent leggy seedlings by providing seedlings with 12-16hr of bright, direct light, as close to the leaves a possible. A hanging fluorescent fixture an inch or two above the top leaves is a good setup. You can even get a special grow bulb with plants’ preferred wavelengths; I paid $10/bulb for mine at Ace Hardware!

Problem #2: Molding or “Damping Off”
I’ll admit, I haven’t conquered the demon of damp-off. And it would be an easy problem to fix, I just…haven’t. Damping off happens when the top of the seedling seems fine, but the stem shrivels up where it meets the ground. Eventually, it shrivels into nothingness and breaks.

Damping off happens when plants aren’t getting enough air circulation, so soil stays too moist for too long. Air circulation doesn’t just help dry the soil, it helps strengthen the seedlings’ stems through constant, slight agitation. This tells the plant that it needs to grow strong roots and stem to prevent tipping over in the “wind.”

Prevent damping off by providing gentle air circulation for your seedlings. Turn on a ceiling fan or use a small oscillating fan that can give your seedlings a light breeze for at least a few hours a day.

Problem #3: Sudden Decline
Has this happened to you? Seedlings are beautiful and strong, and then one day, they start to yellow, start to shrivel, or just sort of…slow down.

Seed starting mixes (often peat-based…see my last newsletter about why that’s both normal and bad!) are great for germinating seeds (germinating is the very first part of a seed’s growth, when it first emerges from its shell). But they don’t contain the nutrition that larger seedlings need. Larger seedlings (seedlings that have one or two sets of leaves) need supplemental nutrients, preferably in liquid form.

Prevent malnourished seedlings by watering them with a diluted liquid fertilizer once a week. I chop up banana peel, and cover it with water in a large mason jar. Then I ferment it in a dark and cool place for a week or more. It smells heinous, but it makes for a great—and nearly free—liquid fertilizer.

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Cheat Sheet #1 - The Classic

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Should I avoid peat-based soil mixes?