To prevent frost you want to keep the micro climate around your plants warmer than 32F. Here are a couple of options when it comes to keeping your plants warm.
I have collected old sheets, blankets, tarps and any large sheets of plastic from my family and friends for several years. On nights where we are projected to drop near or below 32F I head outside before dusk to 'tuck in' my garden for the night by covering everything the best I can. You want to make sure you do this before dark so the ground has not lost all its warmth already AND make sure the covering goes all the way to the ground to trap that heat in.
When covering your plants it is best to drape the material over a frame of some sort rather than over the plant itself if possible. Sometimes all it takes is to place one or two stakes strategically in the garden to give some lift. If it is not possible to drape over a structure than drape light weight covers over the plants themselves... something is better than nothing at all! :}
Be sure to remove the coverings in the morning after the frost is gone so that the plants do not overheat.
There are a couple of options here...
-Watering the soil in the late afternoon allows the water and darkened soil to absorb some of the last heat of the day. Water looses heat at a slower rate than the plants or air. By watering the soil you will be able to trap some of the day's heat in the soil longer and keep the micro climate around the plants warm longer.
-Water the whole garden in the late afternoon/early evening. The concepts related to warming the soil and slower heat loss apply here as well. The water on the leaves has the same effect of slowing the cooling of the plant and air around it. I have observed farmers and talked to fellow gardeners who expand this concept and water all night long. The drawback to watering all night for the average urban gardener is the cost. When you are paying for water, it just is not very cost effective.
Note: if you combine watering and covering, be sure to keep the cover off from the plant or you will loose most or all of what you hope to gain.
3. Radiant Heat ("Hot Water Bottles")A simple way to heat up a small space is to create mini solar heater. You can do this by placing some kind of large dark object(s) near your plant(s) to absorb heat during the day and slowly release it at night. I used this concept in my small greenhouse this spring by spray painting several milk jugs black and placing them at the bottom of the greenhouse. I also had a great uncle who would paint softball or slightly larger rocks black & place them near small plants during cold spells in the spring. The key is to have good sunlight to warm the object during the day and then to have it not touching the plant but still close enough to share its heat at night.
I think I will be implementing some version of all three of these. Whatever is your method of frost protection, I hope you are able to extend your garden season beyond this week.
Happy Gardening (and Garden Protecting!) :}