Seedlings Turning Yellow - Knowledgebase Question

Arlington, MA
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Question by joan71
March 8, 1998
I started balsam impatiens in late January. Most plants are about 6" tall and have several pairs of leaves. Some of them, however, are somewhat dwarf, with only 3 or 4 pairs of true leaves and their leaves are rapidly turning yellow.

First it was only the first pair of leaves (not true leaves), which will dry up and fall off, now the yellow is fading true leaves. The impatiens that are healthy looking are in 3" peat pots, where the sickly ones are in 2" peat pots. I haven't begun to use any fertilizer on the seedlings. Should I transplant the 2" pots to 3" pots? Should I begin to fertilizer the plants and if so, what should I feed them?

I'm having a similar problem with my Salvia.

All plants are under a pair of 20watt grow lights. The lights are about 3-5" above the tops of the plants.

Answer from NGA
March 8, 1998
I think you started your seeds a little too early--especially since you used such small (2") pots. This is the problem you often run into when it's really time for those little guys to get into the garden, and it's not warm enough for them.Better to start them a little later, or plant in larger pots, than try to hold back a "bursting forth" seedling.

Since the leaves are drying and dropping off, is it possible that they are being dehydrated? Peat pots are notorious for drying out quickly. Seedlings are soft stemmed and have shallow roots. If the soil dries out evan a little, the plants may die. Always water when the soil surface is slightly dry.

Also, it's time to start feeding them. Use any balanced fertilizer (such as Miracle-Gro or a fish-emulsion or kelp-based one) diluted to about half the recommended strength, and use this solution to water about once a week. You might also move the lights a little closer to the tops of the seedlings.

You might also plant the 2" pots into larger, plastic pots. I would plant them, pot and all, making sure to completely bury the top of the peat pot--otherwise it will act like a wick and draw moisture away from the roots.

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