I've used wall-o-waters/season starters for several years to get an extra early start here in central Texas. I've started as early as mid February. We have frosts or freezes as late as late March. I have about 30 of the walls.
One year I planted a test group with every other plant in a water-filled protector, the others with plastic wrapped around the cages. There was an upper 20s freeze. All the plants in plastic froze and died. All in the walls survived. A side benefit was that the walls protected the small seedlings from our fierce March winds. By the time the plants started to grow out the top the weather was warm enough to remove the walls.
I'm not using them this year since I'm only growing a few tomatoes in Earthboxes due to my health. I described my starting process with pictures over in the container forum.
David R
