The seeds that I start indoors germinate poorly. Why?


The seeds that I start indoors germinate poorly. Why?


Poor or erratic germination of seeds may be caused by improper planting (for example, planting too deeply), uneven moisture, cool temperatures, and old seed. 

Light for Germination

Fine seeds and those seeds which require light for germination should be sown on the surface of the germination medium and then lightly pressed into the medium.  Cover medium and large seeds with additional potting mix to a depth of 1 to 2 times the seed’s diameter. 

Uniform Moisture Levels

Uniform moisture levels are required for optimum seed germination.  To maintain uniform moisture levels, place clear plastic food wrap over the containers.  Flats can also be covered with clear plastic domes.  Remove the plastic food wrap or dome as soon as germination occurs. 

Warm Temperature

Most seeds germinate best when the medium temperature is 70 to 75 degrees Fahrenheit.  Placing containers in a warm location in the house, such as on top of a radiator or near a heat register, usually provides suitable germination temperatures.  In cool environments, electric heating cables or mats can be used to insure warm medium temperatures.

Old Seed

It is best to use seed packaged for the current growing season.  Most seed drops off significantly in viability after 2 to 3 years, even when stored appropriately.  Perform a germination test on seed that is more than on growing season old to determine if it still has good germination rates.


Last updated on
January 19, 2023