Moist soil may absorb more heat and radiate it throughout the night. Cover plants before sundown to trap the stored heat from during the day. If you wait to cover it until after nightfall, the heat may have dissipated. Use frost cloth, burlap, drop cloths, sheets, blankets, or even newspapers to cover plants.
The easiest way to protect from a freeze is simply by covering plants with a sheet or a blanket. This acts like insulation, keeping warm air from the ground around the plant.
Cover Plants – Protect plants from all but the hardest freeze (28°F for five hours) by covering them with sheets, towels, blankets, cardboard or a tarp. You can also invert baskets, coolers or any container with a solid bottom over plants. Cover plants before dark to trap warmer air.
When Should You Cover Plants? Cover your plants at night and remove them during the day when the temperatures rise above 32 degrees F, so that the soil can warm up again. Some outdoor plants won't survive the harsh conditions of winter, bring them inside and use these tips for caring for them through winter.
Know Your Plants' Cold Tolerance
Some frost-tender plants need to be covered as soon as the temperature hits 32°F, while others can handle lower temperatures and/or longer freezing periods. You'll need to look up each of your plants to verify its cold tolerance.
Hardy plants can be hardened off when the outside temperature is consistently above 40° F. Half-Hardy plants may be hardened off at 45° F.
A fabric covering is best because it will allow moisture to escape while still protecting your plants from frost. Fabric coverings will prevent the freezing air from coming into direct contact with the moisture on the plant while also capturing the heat that is radiating from the ground.
Plastic can be used to protect plants from frost, but it's not the best or most effective material. In fact, the horticultural experts here at Green Impressions actually recommend against it. Plastic materials such as vinyl and traditional camping tarps aren't breathable, causing moisture to get trapped inside.
Any gardening expert will tell you, (contrary to what you may believe) that pruning encourages new growth just when the plant is trying to go dormant and new growth doesn't have enough time to harden before the first frost and freezing temperatures hit. Pruning at this time of year will severely weaken the plants.
If the soil is dry and the cold front is not preceded by rainfall, water the landscape before the freeze. Watering 24 to 48 hours before the freeze will elevate the night temperatures by 2 degrees. Don't overdo it. A soggy soil is not healthy for plant roots and will create root disease problems down the line.
From that experience, I've found the best frost protection for your outdoor plants is either free or cheap. Cardboard boxes and brown grocery sacks make perfect frost cover and at the end of the season can be recycled. I keep various boxes on the patio and when frost is forecast simply put one over the plant.
If it stays cold for more than one night, can I keep my plants covered, or should I remove the coverings at some point? A. Our recommendation would be to remove the cold protection covering once temperatures are above 32 degrees.
Four to six inches of bark mulch, straw, or shredded leaves - especially when placed around newly planted trees or shrubs - keeps soil temperatures constant and prevents plants from heaving out of the ground due to cycles of freezing and thawing.
During winter, may opt for fleece covers or frost blanket to keep plants warm while protecting them from cold weather, snow-clogging, and erosion. In same way, small trees can be protected using material called tree wraps.
A frost blanket is a sheet of fabric, plastic, or other material used to cover plants in cold. There are different types of frost blanket, some designed to protect crops, others designed to shield plants in a home garden.
Gardeners in temperate climates can stretch the gardening season using cold frames, but sometimes these aren't enough to protect even hardy annuals from freezing temperatures. Lining the cold frame with newspapers further insulates the structure, providing a few extra degrees of protection on frigid nights.
Here is advice from plant and tree experts about protecting your plants in cold weather. If you don't have frost cloth, cover plants with lightweight cotton sheets or painters cloth that let in air and light. Burlap and blankets, even paper and cardboard will work, but take care not to weigh down the branches.
Don't keep the coverings on your plants for more than two days in a row without removing them in the day since this can cause water to become trapped underneath, leading to fungal diseases and can cause plants to produce new growth that can be easily damaged by cold.
-Don't make the mistake of thinking that a plant can remain covered for a few days when the weather calls for more than one night of frost. The protection needs to be taken off every morning when the sun comes out. Plants can't breathe under a heavy container, a layer of plastic or fabric.
Much like humans, plants need to slowly increase the amount of sunshine they're exposed to or they'll get burned! If you don't harden your plants, the tender plants will get burned by the sun, the shock of cold, or the wind.
For many plants, temperatures below 50°F can cause problems. Adjust thermostats to cater to your comfort, but remember your plants need some consideration. Avoid placing plants near cold drafts or heat sources. Keep plants several inches away from exterior windows.
It's important to pay attention to the temperature dropping when the sun goes down. Once temperatures are consistently between 60 and 45 degrees Fahrenheit, it's a good idea to start bringing your plants inside at night. However, you can keep them out during the daylight hours if the temperature stays above 45 degrees.