SOAKING ~ SCARIFICATION ~ STRATIFICATION
In most parts of the country, March is a good time to be starting seeds indoors. It’s a way many of us can get a jump on the season, as we impatiently wait for better weather which will let us work outdoors in our yards and gardens once again. Starting your own seeds saves money, while allowing you to experiment with new plant varieties that are often not otherwise available. Most annual vegetable and herb seeds are easy to germinate either in natural outdoor conditions or using specialized heating tools. However, some seeds, particularly perennials, require special techniques to “trick” them into germinating. So, whether you start seeds indoors or in your garden, here is a review of the three “S”s of seed starting. Most seeds will require only one of the three techniques, and will depend on the type of seed.
The purpose of soaking seeds before planting them is to soften the seed coat so that moisture can be absorbed by the embryo, and so that the root and growing tip of the plant can more easily break through the seed coat. Soaking can also be useful in leaching out natural chemicals in the seed which can inhibit germination.
To soak seeds, place them in a shallow dish and cover them two to three times their depth with hot but not boiling water (190 degrees F). For most seeds, 24 hours of soaking is enough. However, if seed instructions specify a longer time, change the water daily. Although some seeds require soaking to germinate properly (asparagus, mallow, lupines, morning glory, okra, parsley, parsnips, perennial pea, and sweet pea), you can also speed up many slow-to-germinate seeds like carrots by soaking them first.
Many seeds have hard or thick seed coats that prevent moisture from being absorbed. This slows down the rate of germination. The purpose of scarification is to help open the seed coat by scratching it with a blade or sandpaper. An emery board or nail file is particularly handy for this purpose. Simply nick each seed, making sure not to cut so deeply through the skin that you damage the seed embryo. Sow seeds immediately, as usual. Seeds that can benefit from scarification are false indigo, mallow, lupines, morning glory, sweet pea, and perennial pea.
Some seeds, especially perennials, are dormant when they’re harvested. The embryo of these seeds will not germinate until the seed is exposed to a period of cold and moisture. This process is called stratification. To stratify seeds, mix them with two to three times their volume of moistened seed starting mixture. You can purchase a pre-mixed medium, or mix equal parts of peat or sphagnum moss and vermiculite or perlite. Place the seed/meduim mixture in your freezer or refrigerator for 1-1/2 to 3 months. (NOTE: Stratification will not work if you chill the seeds in their seed packets, or in water.)
You can also stratify seeds outdoors if your winter temperatures drop to at least 40 degrees F. Simply plant the seeds in flats or in the ground on the north side of your house (this keeps wind and sun from drying out the seeds). Bury the flats in the ground to their tops in the fall and the seeds will germinate in the spring. Seeds to stratify include angelica, bleeding heart, christmas rose, columbine, day lily, lavender, pansy, phlox, primrose, and violets.
Good luck and happy seed starting! We hope that warm spring days find their way to your part of the country soon!