Understanding Damping Off

Understanding Damping Off

48x20 Seedling Heat Mat item #53254
Try our 48x20 Seedling Heat Mat.
Click here for product info.

Damping off is a general term for diseases that attack seedlings in the early stages of their development. It is caused by several different types of fungi. Damping off causes seedling stems to collapse and in some cases can cause newly germinated seedlings to die before emergence. Visually, infected seedlings will show constriction and discoloration of the plant stem at the soil line and toppling over.

Damping off is best controlled through good growing practices and plant culture. Growing according to the following guidelines will greatly reduce problems with damping-off and help to ensure that seedlings are vigorous and healthy.

  • Poor moisture management is the primary cause of damping off! Avoid overwatering. Overwatering reduces oxygen levels in the media, which stresses roots and increases the chance for disease infection. 
  • Use containers with drainage holes and don't leave containers standing in water for any length of time. Allow the surface of the seed starting mix to dry out between waterings once seed has germinated.
  • Remove plastic covers from seed trays after germination to ensure there is good air flower and reduce the humidity level.
  • Thoroughly wash and disinfect any reused containers. Disinfect reused containers by soaking them in a 10% bleach solution (1/4 cup bleach in 2 1/4 cups water) for 10 minutes and then rinsing thoroughly.
  • Use a fine-textured, sterile seed starting mix like Seed Starting Jiffy-Mix or Jung Family Garden Seed Starting Mix. A 50:50 mix of fine-grade vermiculite and milled sphagnum moss is also a suitable mix.
  • Don't crowd seeds when sowing. If seedlings are crowded, remove some of them so each plant has good air circulation.
  • When transplanting seedlings, handle them only by the leaves and not the stem. Injured stems are more susceptible to damping-off.
  • Grow seedlings in a well-ventilated, brightly lit area. Weak, leggy seedlings will result if plants are grown in poor light at very warm temperatures. Seedlings grown in bright light at cooler temperatures will be stocky and healthy.
  • Should you see any infected seedlings, discard them immediately as affected seedlings cannot be cured.
  • You can add beneficial microorganisms to your growing mix by using a mix that contains compost or adding compost (up to 10% by volume) to your seed starting mix. You can also use a natural, biological fungicide like Actinovate to water in your seedlings an help protect them naturally. The beneficial microbes in Actinovate will grow around plant roots, protecting them from disease infection and improving their ability to take up nutrients and water.

Click Here For Seed Starting supplies

Gardener Articles