Pansies and violas bloom for most of the winter in mild climates, and some types will rebound in the spring in cold climates. They're technically annuals, but many varieties drop seeds so they'll come back again next spring.
Any guesses what kind of flowers DON'T like the cold? TROPICALS. When you think about it, it is understandable that tropical and sub tropical blooms don't enjoy the cold environment that the winter months brings. Heliconias, orchids, anthuriums and ginger flowers, all grow in more humid environments.
Beans, cucumbers, eggplant, musk melon, okra, peppers, pumpkins, squash, sweet corn, sweet potato, and tomatoes will all be damaged by even a light frost, but many other crops will survive.
So what's the solution… Focus on frost hardy annuals. Some of these annuals that can withstand 20 degrees or so, including pansies, snapdragons, dianthus, alyssum, dusty miller, viola, and osteospermum. Keep in mind that flowers may be a bit ragged after such cold but the plants should make it through ok.
Petunias thrive when nighttime temperatures are in the 55 to 65°F range, and daytime temps are between 61 and 80°F. They will succumb to sub-freezing temperatures in a hurry, and anything below 40°F may kill them, though Wave® petunias can tolerate temperatures as low as 35°F.
Plants to move inside: Tomatoes, peppers, eggplant and others that will not survive frost. Plants to cover: Potatoes, radishes, spinach, leaf lettuce, beets, mustard. Plants that do not need to be covered: Onions, cabbage, broccoli, cauliflower, carrots, turnips, kale.
Most plants prefer a temperature of no less than 60° F, though many can tolerate as low as 40° F. Along with this, while the improper temperature can certainly be an issue, fluctuations in temperature are the true killer. Learn the ideal temperatures for your green friends so they can be healthier and happier.
Keep them away from direct sunlight and heat vents, as well as cold drafts near a window or door in winter. Avoid placing your arrangement near ripening fruit, which releases tiny amounts of ethylene gas that can age flowers prematurely. And finally, most cut flowers benefit from a daily mist of water.
For most flower types, optimal storage temperatures range between 33°F - 37°F while cold-sensitive blossoms and tropical flowers should be maintained at temperatures above 50°F.
Record cold temperatures (below mid to upper 20s) will damage or destroy many of the flowers of early blooming varieties. The foliage of fully emerged spring-flowering bulbs like tulips and daffodils can also be damaged. Portions of the leaves may turn white and the damaged leaves may collapse onto the ground.
Roses, in general, can survive winters in USDA Hardiness Zones 6 and above (or in temperatures as low as zero degrees Fahrenheit). As such, they can survive very cold climates, but you should still prepare to winterize them to ensure they have all they need to thrive throughout the winter months.
It's important to note that zinnias don't tolerate frost, so make sure to wait until all chance of frost has passed before planting them outdoors. In areas with a long growing season, you may also consider planting a second crop of zinnias in mid-summer for an extended bloom period.
Originating from South Africa, geraniums are happiest in the heat, and can tolerate periods drought with little water. Geraniums, or pelargoniums, are hardy in USDA zones 9-12 in climates of between 20ºF to 50ºF and can survive to zone 7 to temperatures of -12ºF (0ºC) if protected.
Zinnias are sensitive to frost, so do not seed until the last frost has passed in your area. See your local frost dates. Zinnias will grow in a minimum daytime temperature of about 60°F (16°C), though a range of 74–84°F (23–28°C) is preferred.
Some plants tolerate frost and cold temperatures better than others. Plants always killed by frost include summer annual flowers and summer vegetables like impatiens, marigolds, coleus, tomatoes and peppers. Subtropical and Tropical plants are the most sensitive to frost (citrus, hibiscus and bougainvillea).
Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation. Severe or hard freeze - 25° Fahrenheit and colder causes heavy damage to most plants.
A covered porch usually provides protection from light frost, but the garage or sun room is better for freezing temperatures. A couple days in darkness won't hurt the plant. Or move them out during the day and back in at night, if cold temperatures persist.
For the best chance at success for keeping your garden alive through the winter, choose hardy native plants that are used to your area's climate. When the weather forecaster warns of an overnight freeze, cover your plants with burlap, an old sheet or blanket, or clear plastic.
Plastic – Plastic is definitely not the best winter covering for plants, as plastic, which doesn't breathe, can trap moisture that can kill the plant in a freeze. You can use plastic in a pinch, however (even a plastic garbage bag), but remove the covering first thing in the morning.