Which seeds need stratification

This simple treatment of keeping the seeds in cold, dry storage helps increase germination rates by immitating a natural winter dormant period. Many native prairie species require only Dry Stratification. This can be accomplished in temperate climates by storing the seed in Ziploc bags in a refrigerator, or in a rodent-proof container in an unheated building over winter for days depending upon the species.

Most warm season prairie grasses and wildflowers require only 30 to 60 days of dry stratification to break seed dormancy. Many prairie seeds germinate best when seeded in fall, in a dormant seeding.

The exposure to cold, damp conditions over the winter is a nature's "moist stratification," and signals to the seed that it is time to germinate when the soil warms up in spring. Some wildflowers need this process, more than others. A moist stratification seed treatment is used to mimic the effect that winter bestows upon the seed. Members of the legume or bean family can benefit from an inoculation with Rhizobium bacterium prior to planting. All of our legume seeds have been pre-inoculated with this bacterium.

The bacterium works with the plant to form nodules, on the roots of legume plants, which are capable of taking nitrogen from the atmosphere and incorporating it into the plant. Scarification of seed is the process of scratching the seed coat to allow moisture to enter the seed itself.

If a seed requires scarification, gently scratch the seed with a sandpaper block prior to planting outdoors, or prior to moist stratification.

These varieties re-seed naturally in the wild and stay dormant until the proper time for them to start sprouting. More and more gardeners are seeing the benefits of growing native varieties in their landscapes and with a simple technique called cold stratification, you can easily add these wildflowers to your garden in the spring. Many annual varieties, like Zinnias, and Sunflowers, have soft shells and can simply be sprinkled on bare soil in the spring.

But some perennials, especially native wildflowers, have a hard coating that helps protect the outer shell from breaking and sprouting too early.

The good news for gardeners is that the natural cold stratification needed for germination can be forced with just a few materials, water, a refrigerator, and patience. Nature will do what it does best during the winter months and cold stratify the seeds for you. There are quite a few native varieties that should be cold stratified before planted in spring. We chose Prairie Violet Seeds, St. John's Wort, and Tennessee Purple Coneflower as some of our varieties to plant.

There are several perennial and native seed varieties need to be manually broken from dormancy in order to sprout and thrive in your garden.

Learn how to scarify and soak seeds for spring planting. Although this is a comprehensive list of the most common varieties, there are other seeds that do require cold stratification before spring planting. The first step is to gather the materials needed, all of which can be found in your home, tool shed, or with a quick trip to the hardware store.

Now that you have your materials, you can use three different methods for cold stratifying your seeds. This method is very similar to the sand method, but uses peat moss which many of us have lying around somewhere. This is one of the methods most widely used for native seeds, especially milkweed. It is easy, quick, and the materials are usually right in your kitchen ready for use.

The time you need to keep your seeds in the refrigerator depends on the variety, but weeks should be a sufficient amount of time for most seed varieties.

As a beginner gardener, I started dreaming of spring as soon as the holidays were over. As I became more interested in growing things, this time of dreaming turned into planning, and as I became more experienced, a time of planting! Mother Nature is a masterful teacher. So much of what we try to create in our gardens are just shadows of what she does perfectly herself. When we plant certain types of seeds in mid-winter, we are taking advantage of the cold and wet conditions to help break the dormancy of the seeds for us, for easy germination come spring.

This process is called cold stratification. We can recreate this in controlled conditions by mixing our seeds with barely damp sand, vermiculite, or peat moss and putting the damp seed mixture in a container in the refrigerator. But why go to all this trouble when nature is ready and willing to help out? There are generally two reasons seeds could benefit from cold stratification. The seeds of some species go into a period of embryonic dormancy and often will not sprout, or will have a poor germination percentage, until this dormancy is broken.

Other species have seeds with a very hard seed coat, and exposure to the moist cold helps break down this shell for easier germination in spring. Sometimes you will find that both apply. When we let Mother Nature do the work for us, the cold and moist of winter triggers the seed's growth and subsequent expansion, eventually breaking through the softened seed coat in its search for sun and nutrients.

The time needed to stratify seeds depends on species and conditions, though in many cases two months 8 weeks is sufficient. On your seed packets, look for the term "cold stratification".

Often, perennials and self-sowing annuals can sprout after being sown in winter, but if they are not species that require stratification, it's probably a better bet to wait and sow them in spring or start then indoors.

If you are unsure, you can always try and sow a few seeds from your packets and see how they come up for you come spring. This answer depends on where you live, but a good rule of thumb is to wait until winter temperatures are here to stay. Folk wisdom for centuries has suggested that the Winter Solstice is a good time, and while that sounds charming, my experience has been mixed with that date. Here in Asheville, zone 7a, 7b it is usually still too warm for good results.