WHEN TO BRING PLANTS INSIDE. As a general rule, tender plants should be brought in when nighttime temperatures are below 50 to 55 degrees F, even if they are hardy for your zone. A plant's roots are more exposed when planted in a container versus in the ground.
When nighttime temperatures start to dip consistently to around 50°F, it's time to bring plants back indoors. Most houseplants are native to tropical areas and will not tolerate freezing temperatures.
The general rule of thumb is that most plants freeze when temperatures remain at 28°F for five hours. Of course, there are exceptions to this rule. Seedlings, with their tender new leaves, often give up the ghost when temperatures dip to 32-33°F. Tropical plants have differing low-temperature thresholds.
Each plant has a different threshold when it comes to dealing with the cold. Some plants can survive outside even when temperatures hit freezing. Others need to be brought indoors when temperatures reach the mid-40s. Be sure you know this before you plant.
Acclimation. Since outdoor plants are getting much more sunlight than they do indoors, there is a natural acclimation process that occurs where a plant must adapt to the new conditions. Take your time: The best thing you can do to ensure a smooth transition is to gradually move your plants in areas of increasing shade.
Some experts recommend bathing or soaking plants in a bucket of water with mild dishwashing soap before bringing them inside. If your plants are too big for the bucket treatment, spray them with water to remove outdoor dust and soft-bodied insects from the leaves.
If low temperatures loom, cover plants with cloth, burlap or plastic at night. If you use plastic, be sure to remove the covering during the day since temperatures can heat up, causing premature bud growth. Also, when covering, avoid damaging the top part of the plants.
There is no universal temperature for all plants that is too cold, so that is why it is important to do your research. However, it is safe to say if living in an environment with harsh winters and temperatures below 20°F, it is always wise to bring plants indoors during this time, if possible.
First, it's good to know which plants are sensitive to temps around 35 or 40 degrees F. These are common tender plants that will need some protection. Hanging baskets: begonias, calibrachoa, gerbera, impatiens, vinca, euphorbia, and scoparia.
Covering plant material at temperatures between 39-30 with freeze cloth or covering can be effective. Prolonged exposure at temperatures of 28 degrees and below will notice protection results diminish with each degree dropped.
Freeze Warning - This is issued when there is at least an 80% chance that the temperature will hit 32 degrees Fahrenheit or lower. Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation.
If you're looking for tips for protecting your plants from frost, avoid using garbage bags as plant covers. Trash bags are not the best protection against frost damage, primarily due to their material. Most garbage bags are made out of low-density polyethylene plastic.
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.
This is usually about four to six weeks before the average first frost in your area. A couple of weeks before the temperatures dip to 50 degrees or below, put your potted plants underneath a tree or onto a covered porch so they can start adjusting to the reduced light they'll get in your home.
Try to get begonias indoors before the temperature drops below sixty degrees Fahrenheit. Fibrous varieties can make excellent houseplants, provided they have enough light exposure and moisture— keeping up the humidity levels inside is a helpful measure to take. It is best to leave tuberous-rooted begonias dormant.
Saturate the soil with 1/2 cup hydrogen peroxide 3% per 1 litre water. Put wet soil in a watertight container and leave overnight before planting. This kills pathogens such as fungi and bacteria including insect eggs and nematodes (roundworms).
Many tropical plants cannot survive temperatures below 40 degrees. If you cannot move your pots (with annual or perennial plants), or you have tender plants in the ground, cover your plants.
So will peppers survive 40 degrees? To sum it up, most peppers won't necessarily DIE from 40˚ F temperatures, but their growth can be stunted, and they may be slow to recover so it's best to keep them warm if possible.
H2 Rating - 34 to 41° F (1 to 5 C)
Overall, these annuals are the most delicate of all the hardy annuals - one might call them half-hardy since they are really only hardy into the few temperatures just above freezing. And it's important to NOT let them freeze.
The general answer is around 90 degrees F, with some exceptions to the rule. This means that when temps rise above 90 and remain there for a lengthy spell: Leaves wilt. Water evaporates into the atmosphere more quickly in high heat, draining a plant's reserves.
ACCLIMATING YOUR PLANTS TO The INDOORS
Avoid moving plants directly from outdoor conditions to the indoors as this can stress them. Instead, gradually acclimate them by placing them in a shaded or partially shaded area for a few days. Don't be alarmed if your plant drops some leaves soon after being brought indoors.
So, yes, it's been cold at night around Southern California, but folks, 45 degrees is a still a long way from the freezing temps that can burn our tender tropicals and other plants, like a multiday cold snap in 2007 that severely damaged crops in Central and Southern California.
It's time to bring any plants you want to save indoors when nighttime temperatures start to drop into the 50s. Some plants, such as citrus trees, can tolerate temperature dipping into the 40s, says Trejo. But it's better to plan ahead instead of risking it if the first frost of the season sneaks up on you.
Some larger or hardier plants can withstand lower temperatures with the right covering or protection. Bring these potted plants onto a covered patio, or place them in an unheated garage to protect them from frost and long-lasting freezing temperatures in winter.
Overwintering Marginally Hardy Plants
You will simply have to do more than leave the pot sitting on the patio. The first option is to place the pot in an unheated garage (or other unheated but protected spot).