When you cannot wait to get your tomato plants into the soil, you may encounter chilly weather during the first few weeks after planting. When overnight frosts threaten tomato plants, cover tomato plants prior to the evening hours and the insulation from the cover will help preserve the delicate foliage of the plants. As long as you protect your tomato plants with a light layer, they can withstand frosty temperatures and you may have extra early tomatoes because of early planting.
Pound the stakes into the soil approximately every 3 feet along your rows of tomatoes. If you already have support stakes or cages surrounding your tomato plants, omit the stakes.
Spread the old sheets over the tomato plants with the stakes or tomato cages supporting the sheets and keeping the sheets from contacting the foliage of the tomato plants. Place the sheets over the tomato plants in the late afternoon when you expect frost during the upcoming night.
Anchor the sheets around the tomato plants with the large rocks.
Leave the sheets over the tomatoes until the following morning. Wait until the temperature rebounds back over 40 Fahrenheit and remove the sheets.