Seed Stratification

• Perennials native to cold climates require a period of cool weather followed by warm weather. A practice called stratification achieves this result artificially. Most seeds require a cool moist period of 34 to 41 degrees. Enclose seeds in a sealed plastic bag with a small amount of moist sand or sphagnum moss. Place in refrigerator for 10 to 12 weeks. Check periodically to see that the medium is moist, but not wet. Condensation is expected. This method helps most seeds to germinate at the same time.
  
  

Planting Seed

• Sow the seed immediately after stratification. Handle the seeds cautiously, as small roots should be emerging. Sow the seed in short rows at the recommended depth in trays of loose, well-aerated seed-starting medium. Cover them with a fine layer of peat moss or vermiculite.
  
  

Light Requirements

• Light can either help or hinder germination of seed. Determine the needs of individual varieties. With light-requiring seed, the fine covering of peat moss or vermiculite allows some light to reach the seed without inhibiting germination and helps keep soil uniformly moist. Place tray under a fluorescent light suspended 6 to 12 inches above the seeds for 16 hours a day.
  
  

Water Requirements

• Germination cannot happen without water. The amount of available water in the soil affects the intake of water by the seed. Keep the growing medium moist at all times but never wet. Once germination begins, a dry period causes kills the seed embryo.
  
  

Temperature

• A controlled temperature not only affects the germination percentage but also the germination rate. Some seeds germinate in a wide range of temperatures, whereas others require a narrow range. Generally, 65 to 75 degrees is best for most seeds. Place the trays on radiators or heating mats to maintain optimum temperature.