An online tool from Cornell University can help with your decision making.
I am frequently asked, “How late is too late to plant cover crops in the fall?” There is
no decisive answer. Tell me what the weather will be like for the next six weeks and I
would be confident in recommending the last date for establishing a cover crop.
It boils down to understanding the weather trends for your area and the amount of risk you may want to take, just like you do with your cash-cropping decisions in the spring. If it’s mid-June and still too wet to plant corn, do you stay with corn or switch to beans? The same thinking applies to cover crops.
Know the species potential
It’s well-known that cereal rye can be planted anytime in the fall and will undoubtedly grow. You may not see it until spring, but it’ll be there. The question is, when do other species reach the end of a justifiable planting window? It is important to know that there are winter hardiness and late planting date variations within a given species. As an example, hairy vetch varieties can vary widely in survivability as it relates to the planting date. Knowing how a specific species performs in your area can only be known with personal experience or a trusted seed sales person.
It’s never too late to plant cereal rye. You may not see it in the waning weeks of the fall, but it’ll pop up as soon as temperatures begin rising above 40 degrees in the early spring. If you are planting late, you should use a higher seeding rate – up to 2 bushels or more — if the strategy is to use cereal rye for forage.
There are several guides you can utilize to make late planting decisions.
Use them to determine your risk in making the most of your cover crop planting