Frost warnings for Ann Arbor for tonight; that's kind of late.
In the spirit of gardeners everywhere, here's some collected recommendations for dealing with frost damage in your garden.
From Zimbabwe and Farm Radio International:
Protect Tomatoes from Frost
By Livai Matarirano, Zimbabawe
You can grow tomatoes even in cold weather. A farmer in Zimbabwe, Mr. Francis Handwa, uses cooking oil or milk bottles filled with water to keep tomato plants warm. This is a good alternative to covering tomatoes if used bottles are easy to get. Here is how he does it.
Francis fills cooking oil or milk bottles with water until they are three quarters full. While the plants are still young, he places the bottles upright on the ground among the tomatoes. He places one bottle beside every third plant in every other row. He makes sure that the neck of the bottle appears above the plants. When the plants get taller than the bottles he places stakes beside the tomato plants. He hangs a bottle on each stake with a string. The bottles hang 10 centimetres above the plants.
Tomatoes like it hot! They will die if exposed to frost. Make sure to plant them after the last frost.
Tip#1: Cover your young seedling if frost is predicted. A simple and easy cover for small seedlings is to buy large or extra large plastic disposable cups. Place them over the seedling at dusk, and remove them in the morning. There is usually little or no wind on nights with frost, so they are not easily tipped over.
Tip#2: If you get a light frost overnight and you did not cover up your plants. Go out early before the sun rises, and spray your plants with the garden hose. This melts the ice off the plants and may save them.
From Tomato Casual:
If a more serious frost is coming, cover your plants with something to keep the frost from ending up on the leaves. I like to use sheets but anything like plastic, sheeting, newspaper or other material that can be used like a gentle covering will suffice.
Leave the cover on until the temp breaks that frost level in the mid morning and your plants will be none the worse for wear. Do not, however, leave plastic on the plants in the hot sun as this is damaging to the tomato plant and all your attention will be wasted.
If you still have tomatoes on the vine, keep bed sheets on hand. When frost is in the forecast cover the vines early afternoon before the sun starts setting. This will help trap the daytime heat before the soil cools. Also, try to extend the sheets to cover as much ground as possible. I stretch mine out and put a stone on top to hold it in place. This creates a tee pee which too traps more warmth. Remove covering once the sun comes up.
From the Columbia Missourian, Put plants to bed with a blanket tonight
According to Sapp, it’s best to cover plants with cloth. A simple flannel bed sheet will do the trick, but make sure that it is lifted slightly off the plants so they have a little breathing room. Cardboard also works, Sapp said. Take a box, place it over low plants and flowers, and then open the box top during the day so the plants can soak up the sun.
Contrary to popular belief, Sapp said plastic isn’t the best option for covering plants because it doesn’t sufficiently shield them from frost. Stick with cloth and cardboard to save the seedlings.
From Rutgers University, Planting and protecting warm season vegetables
Water walls- There are various clear plastic devices that have long tubes connected in a circle. Once the tubes are filled with water, they will stand up on their own and provide a great deal of frost protection for early tomatoes. The water filled tubes heat up during the day and retain heat during cold nights to protect plants. These thick water walls provide effective insulation to counter cool temperatures. The water walls need to be staked to prevent them from blowing over with strong winds. After frost dates have passed, these devices can be removed.
Stay warm, and keep your tomatoes protected.