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What's Wrong With My Seedlings?

If you are new to starting seeds indoors, there are a few problems you might encounter. Here’s what they are, and what to do about it:


1. Damping off. If the stems of your little seedlings start to get thin at the bottom, if you see spots on their leaves, and/or if they simply fall over and die, they may have damping off. The sight of mold as your seedlings emerge from the soil may also be a symptom.

Prevention is key. You can use sterilized seedling mix. Some gardeners even bake their seedling mix as a preventative measure. Be sure all pots and tools are also sterile, and use only clean water. Keep the seeds as warm as possible and don’t over water them. As with mold (more below), be sure to have good air circulation.

2. Mold
. This fungus, whether it is green or white, is not an uncommon freeloader where there are any damp conditions. When it happens to older seedlings it is less fatal. The best way to deal with it is to give the seedlings some air. If your trays are covered, uncover them. Put a fan nearby to get some air circulation, or if the weather is warm enough, put them outside. Water your seedlings less, and if possible, from below. If the mold is spreading, separate the infected plants from the others. Treat by spraying lightly with a natural fungicide like Neem oil. I’ve also heard covering them with a layer of vermiculite helps, but I haven’t tried it yet.

3. Poor Germination Rates. Failure to germinate can be a sign of damping off or it may just be you have bad seed. This year we had two sowings, 8 plants each, of one tomato and one pepper that did not sprout any seedlings. We’ll chalk that up to immature seeds being saved.

Remember also that some seeds just take longer than others, so don’t give up too soon. In the picture above, all seeds were started at the same time, including the ones that have already been transplanted. All the peppers and tomatoes we planted took longer than any of the cole crops, for example.

Seedlings slower to germinate than others of the same batch may not produce as well as their flat-mates. Consider this when choosing which plants to put into the garden.

4. Legginess
. Probably the most common problem faced by gardeners is long, thin-stemmed seedlings. This is caused by the light source being too far away from the plants. The recommended distance for starting seeds is 4 inches, so get it as close to this as you can. Here again, the fan you were using for air circulation will also help the seedlings to develop stronger stems.

So don’t worry if you see these problems—even seasoned gardeners have probably dealt with all these issues at some point, and may still be doing so. Eventually you get a system that works for you, so keep at it.

Gardening Jones is a master gardener in Pennsylvania. Learn more
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