Or instead of the candles, try about 3-5 gal jugs of water inside the cage surrounding the plant. The mass of the water should protect for at least 3-5 degrees. More if it was in the cage surrounded by clear plastic for a few sunny days to warm up. The clear plastic would also warm up the soil and that will also help.
Check out my "early planting" page here
http://knapps-fresh-vegies.netfirms.com/tips.html
Carol