I have seeded red clover and it was quite hardy through the winter and could tolerate mowing. This season i am clearing off a bed after years of being covered with plastic mulch and have started seeding white dutch clover. I am seeding now as i continue to remove crab and Bermuda grass.
This clover is inoculated so i am counting on some nitrogen and life in the soil. It says to give 40 days before the first killing frost to ensure the clover establishes so i should have plenty of time. I plan to keep using the white clover around my crops once they are in and growing.
If you are planting a crop that is a
perennial than just check around at how long they need to be established before frost. As long as you don't plant them too late they should be with you after they die down in the hard winter. Next spring they will come up and be a living mulch.
If you are doing an annual Plant then it will depend on if you want it to go to seed, or just remain immature so when it dies it covers the ground until the next spring. If it is allowed to go to seed before winter then it will be germinating next year along with your crops.