Tuesday, October 24, 2017

Stratification and Vernalization of Seeds for Fall Planting By Joyce D’Agostino

With the arrival of fall, typically most gardeners feel that their work is done, other than possibly pulling vegetable plants that are finished and raking leaves. 

But if you would like to get a head start on planting some great flowers for next season, fall is a good time. There are actually some plants whose seeds need to have a certain amount of cold and darkness in order to germinate and establish. We are all familiar with planting flowers and vegetables in the spring, but all plants have different preferences for reseeding and growing. For example, some perennials and biennial plants are best sown in the fall to allow them to develop a strong root system. This method is called Stratification and Vernalization.

Stratification means that some plants need the moist and colder environment before they can germinate. The most natural way to do this is to sow these seeds outdoors now. If you have to wait until spring, you can still mimic this process by putting the seeds into a bag of soil or perlite and refrigerate for the amount of time indicated on the packet. Vernalization means that the plant has the ability to flower in the spring after this period of cold and darkness.

Just like a gardener must plant tulips and other spring flowering bulbs in the fall, some plants such as Iris, Larkspur, many wildflowers and Coneflowers can be sown now into the cooler soil. By sowing now, then plants can develop roots and leaves during some of the milder times of the fall and then return in the spring with a show of flowers. Once established, many of these flowers will return for many seasons.

Consult the seed catalog or seed packet to see which varieties of plants do best with a fall sowing. For more information, consult bulletins like this one from The Gardens at Spring Creek for a list of typical flowers that need stratification: Growing Wildflowers From Seed by Sherry Fuller.