You’ve scrubbed the pots and filled them with planting mix. You’ve selected the perfect variety. You’ve watered, heated, adjusted lights and finally, after watching and waiting, Ta Dah, they’re up! The day your seeds poke their little heads above the soil is a day for celebration. After days of babying them, the first sign of green causes a smile to touch our lips, if not our hearts. Yesiree, that tiny seed is going to give us tomatoes all summer long; or broccoli, or petunias or peppers or zucchini or daisies.
One morning, when you get up to admire your plants, you’re horrified to find them toppled over at the soil line and your crop destroyed. Why Me? you might me asking (crying, screaming, wailing). Well, I think I know the answer. You’ve been invaded by a pesky fungus that’s called damping-off.
Damping-Off is a common problem caused by several fungi and can infect and kill any type of seedling from flower to veggie. Wet soil and a high nitrogen level aggravate this fungus. Damping-off can kill seedlings before they even break through the soil, but usually we notice it when the fungus rots the stems at the soil line overnight and we wake up to fallen seedlings. Even though damping-off can be deadly, its window of opportunity is short. After a seedling grows for a few weeks, the stems toughen up and the damping-off fungus is no longer a threat.
Plants in containers are more likely to have trouble with damping-off than plants that are grown in the ground. That’s usually because the growing conditions indoors are just right for this fungus to become established, although a cool, cloudy wet spring can cause it to happen outside, too. There are several things that we can do to help prevent damping-off from attacking our seedlings when we’re starting plants inside.
First, use sterile containers, especially if you’ve had this problem before. One-part bleach to 9-parts water is a good solution for sterilizing planting containers (and other garden tools when needed). Use a soil-less, sterile seed starting mix and make sure your containers and the planting mix have good drainage. Don’t use garden soil to start seeds indoors. Don’t crowd your plants. Good air circulation is essential. Once the plants have emerged, thin them as soon as possible. If you have one, set up a fan to blow on them a couple of times a day. This will increase air circulation and decrease the chance of the fungus getting established. It will also strengthen the stems of your seedlings making them less susceptible to the fungus and better able to hold up when they get moved outdoors. Give the seedlings plenty of light and don’t over water or over fertilize. A thin layer of a dry material, such as sand, vermiculite or perlite sprinkled on the soil helps keep the stems dry at the soil line where the fungus attacks. Something that works even better is a thin layer of sphagnum moss. It keeps the surface dry but also has anti-fungal activity, which reduces the chance of fungal growth. The seeds could also be treated with a fungicide before planting.
With the right cultural requirements and a little bit of luck, you might end up with the first produce on the block or a blue ribbon at the fair. It’s time to get started. On your mark, get set, go!