I had my girls in the ground before freezing nights were over, and I covered them each night with same five gallon buckets I use to grow in my grow room ( the kind restaurants get pickles and things in ),and as you can see by pics they did just fine. I'm here in Colorado, and nights are only now hitting in the low 40s. If you use five gallon buckets, you need not worry about cutting holes as buckets hold plenty enough air to hold a baby plant over night. These girls have been in the ground since April 16th. The cold slowed them way down at first, but not a big deal as they still have 5-6 months of fun in the sun to go.
It gets really windy here and the bricks in pics I used to keep buckets in place. If you look close you'll see that because of winds, these plant's stems are about as big around as pencils even though biggest one is only about 14" tall. Now when the wind blows it barely ruffles the leaves. I figure it can only be a good thing as buds should be no problem for these girls to hold up.