Tomatoes, peppers, eggplants, cucumbers, squash, pumpkins, any melon, basil, and green beans need to be protected in the vegetable garden. Most annual flowers are fairly susceptible to frost damage. So if you bought a flower in a small plastic three or four pack, that plant probably needs to be covered.
Vegetables, annuals, and tropical plants planted outdoors early in the season are the most important plants to protect during a late frost or freeze event in spring. Protecting emerging spring bulbs and perennials is not necessary.
A light frost may cause minimal damage while a severe frost may kill plants. Young, vulnerable plants are much more susceptible to a light freeze, which occurs when temperatures are 29 to 32 degrees Fahrenheit, while mature plants may only suffer from short-term effects.
A "killing frost" is now considered to be a temperature of 28°F in the United States, but in 1916, the type of frost was determined by the level of damage incurred.
There are, of course, many variables that can affect winter hardiness in a plant, but in general, my rule of thumb is as long as the mercury stays in the 20's at night and rises above freezing during the day, our plants should be just fine.
While they are hardy and will comfortably tolerate the cool, almost-freezing, temperatures fairly well, they are not immune to frost. Just one frosty night can do them in.
Some say the hardiest are the ones in the Arctic, and some say that this plant should withstand the driest and low-humidity environment on the planet. Hence, Purple Saxifrage and Welwitschia mirabilis could be named the hardiest plants in the world.
The pansy's cheerful appearance and sweet, subtle scent belie its ability to survive spring freezes, fall cold snaps, and even mild winters.
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. Bed sheets or comforters work best for covering large plants and shrubs.
Freezing temperatures may damage or destroy the newly emerged foliage of perennials, however, their roots and crowns should be unharmed. The damaged perennials should send up a second flush of growth in a few weeks.
Plants to cover: Potatoes, radishes, spinach, leaf lettuce, beets, mustard. Plants that do not need to be covered are onions, cabbage, broccoli, cauliflower, carrots, turnips, and kale.
Although frost will not cause as much damage as a hard freeze, you should prepare certain plants ahead of cold weather. Despite its convenience, there's one item you should stay away from to cover your plants. If you're looking for tips for protecting your plants from frost, avoid using garbage bags as plant covers.
Semi-hardy vegetables that can withstand light frost of air temperatures in the range of 28 to 32 degrees include beets, carrots, parsnip, lettuce, chard, garden pea (before flowering), Chinese cabbage, endive, radicchio, cauliflower, parsley and celery.
Kalanchoe integra (Never die)
Evergreen flowering perennials will keep their green foliage all year, long after the blooming season is over. Many herbs are particularly known for being great practical flowering plants with evergreen foliage, such as Lavender, Rosemary, and Salvia, among others.
Still, these wilted blooms might help protect your mums once the weather temperatures decrease. According to outdoor water maintenance specialists, Gilmour suggests using mulch to cover the base of your mums when the temperatures reach 20°F—this can help get the soil at an even temperature through insulation.
Three Ways to Overwinter Mums in Pots
Keep in mind that the ultimate goal in overwintering your mums in containers is to keep each plants' roots and stems from feeling harsh freezing temperatures. Nice and cozy, is the plan. Also, winter care includes deadheading them back BEFORE storing them for winter.
If frost is coming your way, take these steps to protect your plants: Water your plants just before midday. Moist soil can soak up max sunlight and hold the sun's heat before nightfall frost sets in.
Plants native to the subtropics are in danger below 40 degrees F and pretty certainly going to be killed at 32 degrees F. Plants native to the tropics are often damaged below 50 degrees F and perish at about 40 degrees F.
One of the first signs plants are too cold is the wilting or drooping of leaves. Normally resilient and perky, leaves that begin to droop or wilt can indicate that the plant is unable to properly regulate water within its tissues.