Growing Native Plants from Seed
Many species of native seeds are dormant and will not germinate until they have experienced a specific set of environmental conditions. This protects the seeds from germinating in the middle of winter and gives them the best chance for survival. Seed dormancy can be broken naturally or artificially.
To naturally break seed dormancy you will need to sow seeds directly in the ground in the fall. The seeds will experience winter temperature and moisture conditions and germinate in the spring.
To artificially break seed dormancy the seeds can be placed in a moist medium and kept cold in the refrigerator for three months (cold moist stratification). Scroll down for more information on cold moist stratification.
Direct Seeding in the Fall
Fall is the best time of year to sow seeds directly in the ground for most native plant species. If you sow your seeds directly in the ground in the fall you do not need any of the following seed treatments to break dormancy.
Treatment A: No Treatment Necessary
A few native seed species such as yarrow and black-eyed Susan do not require any special treatment before sowing. Plant seed in spring either directly in the ground or sow in pots for transplanting later.
Grasses require 90 days of cold dry stratification before sowing. Our grass seed is stored under these conditions and is ready for sowing.
Treatment L: Needs Light to Germinate
Some native seed species require light to germinate. Sow directly on top of the soil and keep moist until germination. If you are sowing the seed in pots you can sprinkle the seed with a thin layer of vermiculite after sowing.
Treatment C: Cold Moist Stratification
Another method for growing native plants from seed involves creating winter conditions artificially (stratification) and then sowing the seeds in pots or outside if conditions are suitable.
The most common dormancy breaking treatment for native seeds is cold moist stratification. The seeds are kept moist in the refrigerator for one to three months and then are planted.
Small plastic bags, vermiculite, coffee filters, seeds, water, pencil or permanent marker.
Label the coffee filter with the name of the species and the date (or you can label the plastic bag).
Place two handfuls of vermiculite in the plastic bag. Add water until the vermiculite is thoroughly moistened, but not so much that there is excess water at the bottom of the bag.
Place the seeds in the coffee filter.
Or you can put the seeds directly in the vermiculite. After the cold moist treatment you can sow the seed-vermiculite mixture.
Put the coffee filter with the seeds into the plastic bag with the vermiculite, making sure that the coffee filter is in contact with the vermiculite. The coffee filter should soak up water from the vermiculite and become damp.
Make sure that the bag has air in it, the seeds need to breathe!
Place the plastic bag in the fridge. Check periodically to ensure that the vermiculite does not dry out. Plant immediately if the seeds begin to germinate.
After three months, remove the bag from the fridge and plant the seeds.
After stratification the seeds will be moist and stuck together on the filter paper.
In order to made it easier to spread them evenly you can mix them with a small amount of sand. The sand-seed mixture can then be spread over the soil.
There are other methods of cold moist stratification. The important part is that the seeds are kept moist at refridgerator temperature for the appropriate amount of time in order to break dormancy.