It's safe to move your plants outside when the outdoor temperatures stay consistently above 50°F. Pay attention to the weather report. If nighttime temperatures are set to fall below 50°F, bring your plants in for the night. Bring them back outside when temperatures rise.
Growing Annuals From Seed
After hardening off the annual seedlings, you can plant hardy annuals if the temperature stays at 40 degrees or above.
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.
The best time to bring plants inside is when nighttime temperatures start to dip below 55 to 60 F. (12-15 C.). Before bringing container plants indoors, check for pests that may be living in the soil.
An important factor in the chance of survival is how long the plants were exposed to cold temperatures. A few hours can do the job, depending on the plant. Generally, though, it takes 12 to 24 hours of exposure to cold temperatures to completely kill most tropical plant species. If you're in doubt, check the roots.
Frost protection should be removed every day, but row covers can remain in place for weeks or months. When the weather begins to dip, it can affect the plants and shrubs. Plants at 39 degrees can begin to feel the chill and require a cover just to be safe.
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.
The hardiest of flowers can be planted as soon as the soil in your garden can be worked, even if it's several weeks before the last frost of the season. For half-hardy flowers, hold off until a couple weeks before the final frost, and for tender flowers, plant when there's no chance of frost for the rest of the season.
Cold weather, even if it doesn't drop below freezing, can harm cold-sensitive plants. Freezes are rare, but frosts can occur at above-freezing temperatures. Even temperatures at 45 degrees for more than several hours can harm some tropical orchids.
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.
It's safe to move your plants outside when the outdoor temperatures stay consistently above 50°F. Pay attention to the weather report. If nighttime temperatures are set to fall below 50°F, bring your plants in for the night.
While indoor plants quite enjoy the fresh air and the sunlight of the outdoors, you can't just take your houseplant and move it outside randomly one day. Otherwise, it will fall into a state of shock and could die. It's better to slowly adjust the plant to their new home.
It's important to keep an eye on the weather – specifically the night ranges – and ensure that your green friends are never outdoors in degrees lower than 45 degrees. If you care for tropical plants, anything lower than 40 degrees will cause severe harm.
Summer bedding plants should be planted out in late May or early June and in September or October.
The general rule of thumb is that when a seedling has three to four true leaves, it's large enough to plant out in the garden (after it has been hardened off).
Bedding plants are often on sale early in the year from March onwards, and the temptation is to plant them out. Because bedding plants are tender (which means they are not frost hardy,)it is very important that bedding plants are not put or planted outside until the risk of frost has passed.
If a sudden cold snap shows up in the forecast after you've planted, you can always cover them overnight to be on the safe side. If you do cover plants - be it new or tender perennials or annual flowers or vegetables - cover only overnight. Remove your covering once the temperature goes above freezing the next day.
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.
Water Them For Regrowth
If your frozen plants appear dead there are a couple of important things you can do to help revive them. First, keep watering your frozen plants. Water is essential for any plant to remain healthy year round. You might also try adding an enhancer to the plant.
The greater the difference between day and night temperatures, the taller your crop will be. That means that cool night temperatures and warm day temperatures (greater temperature difference) will result in tall plants.
Yes – if you secure the plant properly. Garbage bags work to cover plants and protect from frost, but they must not be allowed to touch the plant's surface. Use stakes and supports to create a tent-like structure over the plant, which will retain warm air. Make sure the trash bag goes all the way to the ground.
Acclimate tender plants
Start by keeping the plants outdoors during the day any time the temperature is 40 degrees or above. After several days, they should be able to handle the cooler temperatures. Be prepared to move them indoors when the temperature dips below 40 degrees.
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.