You may have noticed some of our seed varieties state the need to be planted in late fall or “stratified” prior to spring planting. But what, you ask yourself, is stratification and how do you do it accurately?
Natural Stratification – By planting in the fall, nature takes its course and the seeds are treated naturally. You can either plant the seeds in the ground, or in seeding trays in an unheated building or greenhouse. When the soil warms up in the spring, the seeds should sprout readily.
Simulated Stratification – We start almost all of our seeds by means of a simulated stratification. We do this by putting the seed in a sterile medium (sand blasting sand works well for us, but other mediums will work) in a plastic bag in the refrigerator for several months. The medium should be dampened, but not have standing water in the bag. This will usually be enough to break the dormancy of the seed. Three months is ideal for many species, but if you are short on time, (who isn’t) a month may help somewhat. Generally, the closer to three months of stratification, the better the germination you will see.
Anise Hyssop is a good candidate for stratification.
Not all seeds need to be pretreated with cold in this way, but if you buy a seed packet and notice that it mentions needing to be planted in late fall or needing to be stored in refrigerator for a few weeks, here are the details for you!
You will need:
– The desired amount of seeds
– Half a cup(or more) of sand or peat moss (moistened with water until you can form a loosely packed ball of soil
– Ziploc or other sealable bag.
Mix the seeds into the moist sand and seal in the bag. Store in the refrigerator for as many days as your particular seed packet states – the amount of time will vary but many of our seeds should be kept cool in this manner for 60 days before planting. Keep the soil lightly moist until germination, since these seeds cannot germinate in dry soil. 
After 60 days or so, you will then plant the seeds outside just as you normally do when there is no more chance of frost. If the seeds begin to sprout while still in the refrigerator, take them out immediately and plant them in pots indoors until there is no more chance of frost and you’re able to plant them outdoors. 
Happy stratifying, friends!