How to - Seeds

How to prevent damping off

Protect your precious seedlings with these green thumb tips.

Sterilize your soil

Many gardening experts recommend sterilizing potting soil in the microwave for 10 to 12 minutes to kill any residual fungi. You may find it easier to buy seed-starting soil. Unfortunately, many still use peat moss, now considered an endangered resource.

Popular mixes include:

  • NatureMix: Certified organic, made with sustainably harvested peat moss combined with vermiculite.
  • NoDampOff: Long-fibred sphagnum moss, free of fungus and 100 per cent organic.
  • Schultz: A blend of Canadian peat moss and horticultural perlite spiked with slow-release plant food.
  • Mica-Grow Fine: Heat-treated horticultural vermiculite (naturally occuring mineral mica).

Mix your own soil
If you are planning on planting quite a few seedlings, it may be cheaper to make your own soil mix. The Farm and Garden Project at the University of California recommends using two parts compost mixed with two parts peat moss and one part vermiculite, pre-wet. You can substitute coir for the peat moss.

Prevention is the best
Overwatering can be deadly, so how do you get the right balance of moisture? Maurice Bergeron, a horticulturist for Cramer Nurseries in West Montreal, recommends bottom watering: "Put the seedlings into a tray, pour water into the tray and let them soak for about 15 to 20 minutes. Pour off any excess water-you don't want them sitting in water since this can activates dormant fungus."

He also warns against overcrowding. "Seedlings need room to grow and if they are crowded together they won't dry quickly enough and this can encourage fungus spores to grow."

Try an herbal remedy
It's far easier to prevent damping off than to cure it. While it's possible to buy seeds soaked in herbicides or spray them with the fungicide Mycostop or Captan, enviro-friendly herbal remedies are equally as effective:

  • Chamomile: Naturally high in sulphur, this popular tea is a natural fungicide. Make an infusion with three chamomile teabags, steep for 20 minutes, then mist over the seedlings.
  • Cinnamon: Sprinkling the soil surface with ground cinnamon will stop damping off. It, too, is a natural anti-fungicide. Do this only once.
  • Organic gardener Doug Green also recommends using garlic, since it's a natural fungicide. Mash up several cloves, boil in an inch of water, cool the mixture and then use to water the seedlings.

If all else fails, you might want to consider starting from scratch. If you do, be sure to use new pots and soil mix.


Visit  Seed to Supper for more in-season gardening and cooking tips.


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