Seed Starting – Damping Off

Guest post by Beate Schwirtlich

Seed Rot or ‘Damping Off’… What is damping off?

This gentle term describes the death of seedlings by fungal disease, either before or after they emerge from the pod. This sudden plant death can happen for up to four weeks after seeds are started. It actually describers a few different fungal diseases carried in soil or seed. These fungi can survive for years or forever in soil, and are found in all soil outdoors.


  • overwatering
  • unsterile soil
  • dirty growing containers
  • overcrowding seedlings
  • stress, such as low light, cool temperatures


  • Seeds don’t germinate: they may have rotted underground
  • Sudden wilting or discolouration
  • seedling falls over: stem bends at soil level
  • roots of diseased plant are black or brown


  • Clean growing conditions.
  • Clean containers yearly
  • use sterile soil mixes.
  • Water seedlings from the bottom of their containers
  • Avoid overwatering
  • Don’t plant seeds too deep
  • Soil with a low pH: commercial starter mixes average 5.5 pH
  • Good ventilation: moving air
  • Use a soil-less starting mix, such as a peat moss/vermiculite mix. (This is not an environmentally friendly option, however, as peat moss is comes from sensitive bogs.)
  • Plant seeds on soil, but cover with sand instead of soil.

Protect seedlings organically:

  • Mist plants with either chamomile clove, or stinging nettle tea as a preventative. These herbal brews have known anti-fungal properties.
  • A one-time dusting of cinnamon powder or powdered charcoal on the soil surface will also help prevent damping-off.
  • Disinfect containers and tools with very hot water and biodegradable soap: this is the most environmentally conscious method. If you think you have a real problem with damping off, use one part bleach to four parts water, or a 70% solution of rubbing alcohol.

Confession of a lazy grower
I do only two things to prevent damping off: I avoid overwatering, and I provide good air circulation. My seedlings are doing fine.


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