They won't do a darn thing if they aren't ready, but you can build a hoop frame over them and cover it with panda (white side out) every night at sunset, and remove the plastic EXACTLY 12 hours later. This is done on a commercial scale sometimes, and works, but you have to be ON TOP of your timing. No forgetting. No going away for the weekend. No sleeping off a bender.
Not worth it unless you are a pro cashcropper with no other responsibilities.