Hannah suggests that even if temperatures are at freezing and the pot is dry, it's important to water because it will help to better protect the plants' roots. "When plants aren't properly overwintered, they'll have problems come spring," she says.
When the air and soil temperatures consistently fall below 40 F, it's time to stop watering. The ground can't absorb water once the top few inches freeze. Continue to water your plants up until this point so they're as well-hydrated as possible going into winter.
All houseplants require less water in winter. Over-watering is always dangerous, but especially so in winter. Make sure you're not letting your pots stay too wet, and your plants will thank you. Try decreasing cutting the frequency of watering in half, or just water if your plants look thirsty.
General Watering Timeline: If you haven't received precipitation in winter, it's crucial to water your plants. With dry weather, once a month winter watering is suggested. If the dry weather continues, you may need to go to twice-monthly watering.
Avoid watering when temperatures are below 40°F or when sustained freezing temperatures are expected within 24 hours as this water will freeze and not be available to the plants.
Indeed, a plant that is drought stressed will often show more damage after a light freeze. So if they are dry, always be sure to water your potted plants before a freeze to help them better handle the cold.
Good drainage is important and fluffy soil also adds a measure of insulation. Best is to move them indoors wherever there is room. This could mean a garage, a basement or a greenhouse if you have one. An unheated garage will moderate outdoor temperatures and give your plants a good chance at survival.
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.
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.
Plants can go to a maximum of a week without water, however, some plants can go for even longer periods of time, such as for two weeks or even a month. It would depend on the type of plant and its drought tolerance level.
Watering from the top down can help flush excess salts and mineral deposits to the bottom of the pot and eventually out of the drainage holes. Constantly bottom watering will keep these salts and minerals in the potting mix, so top watering can help keep the root system of your plants healthier.
It's common for surface soil to dry out more quickly during the winter months, but this doesn't necessarily indicate that your houseplant needs water. It's time to bring out the watering can when the soil is dry two inches below the surface. Water thoroughly, ensuring the pot drains so no excess water remains.
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.
Generally speaking, if your plant is hardy to two zones colder than the area that you are in, it will be a good candidate for being able to survive the winter in a container in your area. There are some exceptions to that rule, and certain plants are better able to survive in containers through the winter than others.
A heated location isn't always necessary. Moving plants to a space like a garden shed or growing plants in a garage will provide enough protection when it gets cold.
For pots that will stay outside all winter because plants are still growing in them, try to move the pots onto a concrete surface, or use bricks, planter “feet,” rocks or pieces of wood to raise them off the ground.
With reduced sunlight and dry air from indoor heating, winter isn't a time when your plants will thrive, but, with the right care, they can certainly survive. “Less sunlight typically sparks a plant's natural dormancy,” says Casey Godlove, creative director at PlantShed.
Most of the houseplants we grow originated in the tropics or sub-tropics where rainfall is relatively warm. Ice cold water will cause root shock, which may lead to permanent root damage, leaf drop and other problems. Allow the water to warm to room temperature before watering the plants.
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.
Keep outsides valve open so water remaining in the pipe can expand without causing a break. When freezing weather is coming, turn off water to outside spigots and drain all water from the line.
If the soil feels dry, it's time to water. In the spring and fall and in cooler climates, it might be sufficient to water container plants every two to three days. In the summer and in warm climates, container plants usually require daily watering, unless they are succulents or other drought-tolerant xeriscape plants.
Dormant plants need less frequent watering than those in active growth. (If planting in a low desert region, a watering once every 2 weeks may be needed if day temperatures are hot.) Check under the mulch. If the soil feels dry, then water lightly.