Because your plants won't grow much in cold weather, avoid allowing the roots to be cold and damp for a long time. That's a recipe for root rot . Don't leave the pots in saucers; water can collect and freeze. Protect the roots: Keeping heat and moisture around the roots will help the plant survive.
While some plants can survive light frosts, others will die as soon as their cells freeze. Depending on their hardiness, some potted plants will respond to the first frost by going dormant just like garden plants do. However, as the temperature continues to drop, their roots might die unless they are protected.
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.
It depends on the temperature, and specifically the nighttime low temperatures. You'll want to move your houseplants indoors before night temperatures get below 45°F. Any colder, and you're likely to see damage, especially on tender new leaves and stem tips.
Before bringing your plant inside, remove any insects by hosing your plant off with a strong stream of water. I recommend doing this a couple of times. Immediately before bringing them inside, give your plants' leaves, stems, and trunks thorough spraying of insecticidal soap.
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. The added warmth may be enough to keep a plant from freezing during a short cold snap.
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.
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.
You can overwinter potted perennials in an unheated shed or garage. Allow them to naturally go dormant in the fall before moving them inside. Then put them back outside once the weather starts warming back up in late winter or very early spring.
If it is not going to rain before the freezing temperatures arrive, you should water plants thoroughly. This is because moist ground stays warmer than dry ground. Watering the night before the freeze arrives will insulate the root structure of the grass and plants, decreasing the potential for cold injury.
Well-watered soil can actually help the plants pack heat around their roots and better survive cold temperatures. So as long as temperatures are above 40 degrees during the day, water your plants at least once a month during the winter.
Most houseplants are tropicals and prefer temperatures between 65-75°F during the day and about 10 degrees cooler at night. For many plants, temperatures below 50°F can cause problems. Adjust thermostats to cater to your comfort, but remember your plants need some consideration.
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.
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.
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.
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.
Use a frost blanket, cloche or row cover material – not plastic — to insulate the ground around your outdoor plants and keep them warm. Prop the cover with sticks or stakes to keep it from coming into direct contact with the new growth. And, make sure to remove the cover the next morning after the temperature warms up.
In cold weather, water should be trickled slowly into the soil. Water only when air temperatures are above 40 degrees F. Apply water at mid-day so there is time to soak in before possible freezing at night.
Morning watering is actually preferable to evening watering as the plant has time to dry before the sun goes down. At night, water tends to rest in the soil, around the roots, and on the foliage, which encourages rot, fungal growth, and insects.
It can be tricky choosing when is the best time to water plants in winter. Avoid watering early in the morning or late at night, keeping to the middle of the day wherever possible as the soil around plants should be dry at night.