Seeds & Seed Mixes

Seed Stratification & Propagation


Seed Propagation Information PDF
Includes Stratification information on individual species.

All Prairie Nursery seed is “dry stratified” prior to shipping to help break seed dormancy. Some wildflower seeds germinate best when seeded in fall in a dormant seeding. The exposure to cold, damp conditions signals to the seed that winter has occurred, and that it will be safe to germinate when the soil warms up in spring. Some wildflowers benefit greatly from a process called “moist stratification,” which mimics the effects of winter on the seed. These procedures are outlined below.

Most prairie grasses generally do not benefit from moist stratification. Certain species have specific times of the season when they germinate best. Most wildflowers will exhibit higher germination when seeded in the fall. Cool season grasses and flowers, such as Junegrass, Prairie Dropseed, and Asters do best when planted in early spring when temperatures are cooler. Sedges also do better when planted in fall or early spring.

If your goal is to establish both flowers and grasses together, it is best to plant in fall or early spring, provided that the site has been properly prepared and is free of weed problems. Watering can greatly increase germination and overall success in late spring and early summer seedings. For information on when to seed, Click here.

DRY STRATIFICATION

Seed is exposed to cold temperatures for one month or longer. All Prairie Nursery seed is dry stratified, unless purchased prior to mid-January.

MOIST STRATIFICATION

  • Seed is mixed with moistened inert material and stored cold for ten days to three months. Many prairie wildflower seeds show improved germination with moist stratification, while prairie grasses generally exhibit little or no increase in germination.

  • Planting in fall typically achieves the same results as Moist Stratification. It is not necessary to use this pre-treatment for seed that is to be planted in the fall, as dormancy will be broken naturally in the soil over winter.

  • In a plastic bag or re-sealable container, mix seed with an equal volume of moist (not wet) sawdust or clean builder’s sand (if moisture can be squeezed out of the sawdust or sand, it is too wet). Refrigerate at 34-38 degrees F (do not freeze!). Most flower seeds require three to four weeks of treatment. Legume seeds generally only require ten to fifteen days. Some flowers require two to three months. (For specific details see Seed Propagation Information PDF)

  • When planting moist stratified seed, it is best to water the area for one to two months after seeding. Though the seed is conditioned to germinate by stratification, it may revert to dormancy if it does not receive rain or moisture within a certain number of days after planting. All direct seedings in spring or early summer, pre-treated or not, will benefit from irrigation during the first two months after seeding.

LEGUME INNOCULATION

Members of the legume or bean family can benefit from an inoculation with Rhizobium bacterium prior to planting. Your legume seeds have been pre-inoculated with this bacterium. The bacterium works with the plant to form nodules, which are capable of taking nitrogen from the atmosphere and incorporating it into the plant.

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