For a snowy spring, a tomato igloo

I've written before about Walls-O-Water. These $3 plastic sleeves, filled with water, act as a mini greenhouse around individual plants. I used them last year when planting tomatoes two weeks before the recommended Mother's Day frost-free planting date, and it's a good thing. The one tomato that didn't have a Wall-O-Water died a quick and frosty death one night. This year, I decided to push the WOWs to the limit. I'd heard from Wayne Fisher, owner of Good Earth Garden Center in Colorado Springs, told me he once planted a tomato in March using a WOW, "just for bragging rights." That seemed extreme to me, but I did want to get a jump on the growing season, so April13, while it was snowing, I planted a wonderful heirloom Stupice tomato in a wall of water. Monday morning, after the snow had melted, it seemed to be doing fine. The key is to let the WOW sit on the site where you plan to plant for four or five days to warm the ground.
Will planting early make any difference? It's hard to say. It might be better to let the Stupices sit in Good Earth's greenhouse for a few more weeks. Maybe there is no advantage. But I wanted to find out. I plan to plant more on May 1. We'll see by July if an early start made any difference.
If you want to try Walls-O-Water, they are available at most garden stores.