Damping Off: What It Is and How to Prevent It
What is Damping Off?"Damping off" is the popular name for the abrupt dying off of seedlings, whether indoors or outdoors. The seedling collapse and sudden death occur when the plant is successfully attacked by fungal-like organisms called Pythium.
The Plant Disease TriangleHow do plants get diseases? According to the California Master Gardener Handbook, three factors are involved: a weak host plant, a susceptible environment, and a pathogen to cause the disease. For damping off to occur, you need a stressed plant, a wet soil environment, and the presence of Pythium. Our comparison photos below show a healthy seedling next to a seedling that is damping off.
How to Prevent Damping Off
Healthy plant Start with good quality seeds or "healthy planting material" as the academics call them. Choose your seeds with confidence at Peaceful Valley, where we only carry top quality seeds. Use the tips in our Seedling Care video and blog post to maximize the health of your seedlings.
Well-drained, fluffy soil The University of California, Davis says, "Damping-off is worse when soil is wet or compacted." To keep our seedlings in a well-drained and light growing medium we use Quickroot Soilless Potting Mix. Quickroot drains fast enough to keep the soil from becoming water-logged. Don't drown your seedlings, but water them with a mister like the Fogg-It that Tricia uses in our video. The lightness of Quickroot also allows tiny roots to receive oxygen and thrive.
Keep your growing supplies clean Carefully clean your seedling trays and pots between uses. If seedlings show signs of damping off, discard them immediately (and do not compost them). UC Davis has a perfect summary of the role of sanitation in preventing damping off: "Sanitation is important because spores of the organisms that cause damping-off can survive in dust, planting medium, or soil particles in flats and pots. To reduce survival of the pathogens, remove and discard diseased plants and sterilize containers."
Pythium remains as a possible pathogen You cannot eliminate Pythium from your soil without killing other "good" organisms. The old horticultural advice was to sterilize soil before planting seeds, but even Purdue University now agrees that this harms the beneficial soil organisms and that "in sterile soil, reintroduced diseases may spread faster than they would in unsterilized soil." Organic gardening is based on maintaining beneficial organisms in soil.
For more information about planting seeds, and seedling care, watch our videos on Seed Germination, Seed Starting, Soil Blocking, and Direct Sowing. All these videos link to articles in our blog, and our videos and blog articles are research-based. An authoritative book that gives you extensive information on all aspects of starting seeds is The Seed Starters Handbook.
Pick your seeds. Grab some Quickroot. Choose seed trays with pots, or Soil Blockers. Follow these damping off prevention tips. Have happy seedlings!