European-influenced gardening traditions have established spring as the official planting season, leading many good gardeners to make the mistake of assuming they should plant natives in spring as well.

In fact, many if not most native plants are best planted around fall!

Why It Isn’t Spring

Imagine you’re a plant well adapted to survive in a place with harsh yearly winters. You put much if not all of your hard-earned resources into your seeds, each containing the hope for a future seedling. Those hopes are dashed, however, if seedlings sprout late in the growing season, lacking the time to grow strong enough to survive winter. For many native plants, they have better chances sprouting the following spring.

How do you ensure your seeds “know” to wake only after winter has passed? 

One strategy is to invest in mechanisms that prevent germination before conditions are met, effectively creating a dormancy period that demands a “trigger” for growth. For many species, the trigger is 30-90 days of cold, moist conditions, often called cold stratification. 

In nature, this happens automatically. Seeds fall in late summer through autumn, and they rest in moist soil covered by leaves and then snow. Months of cold, moist conditions pass, the land begins to warm up, and the seeds wake.

For many species, sowing un-wintered seeds in spring accidentally skips an important part of their life cycle! The seeds may still remain viable, just waiting for winter.

When Is It?

In general? Mid-fall to early winter. From October 14th to roughly the first week of January, depending on the year’s temperatures and snowfall. 

Personally, I like to say the planting window is over after the first big snow (the one that doesn’t melt away until spring). 

While many, if not most garden species are best planted in this window, each species has their own germination requirements. Some need as little as 10 days of stratification, some take multiple winters (years!), while others require no special treatment at all. 

If you do not know the germination requirements for the native species you want to plant, you can search online for their stratification needs. Use the scientific name in your query, for example, “Zizia aurea stratification”. Depending on the species, you may be able to plant in spring after all!