Fall. The end of the growing season usually won't require as much watering, since temperatures start cooling and precipitation often increases. Also, most hardy plants will start slowing down their growth and losing leaves in preparation for winter, so they need less hydrating.
A thorough watering twice a month during mid-late fall should be sufficient for most soils, though if you have slow-draining clay or rocky soils, you may find that just once a month is enough.
When To Stop Watering Plants in Fall. 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.
In fall, plants do not need as much water as they may have needed in summer. But rather than stop watering altogether, it's best to wean them from weekly watering to every other week to monthly throughout fall.
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.
If your plants are in the ground (versus a pot), the general rule is that plants need one inch of water per week. However, this does NOT mean watering one time per week. That doesn't usually do the job. Plants do best when watered about three times a week, factoring in the rain.
DON'T water too frequently—or not frequently enough.
Instead, opt for a less frequent watering routine that thoroughly saturates the soil. This method encourages the plants' roots to reach deeply for residual water, even when the surface of the soil appears dry.
Creating Watering Schedules for Winter Gardening
Try watering at mid-day — when temperatures are higher—so it can soak in before it freezes at night. Water your landscape once or twice per month from November to April. New roots form in the months of March and April. It is most critical to water during these months.
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.
A lot of plants can handle some neglect when it comes to folks forgetting to water. However, all plants need water to survive. Forgetting to water every now and then or watering a day or two later than you should can result in dead blooms and burnt foliage but these plants can survive that.
Water after rain.
Believe it or not the best time to water is after rain, when the ground has been softened and is more receptive. Extra water at this point tops up the rainfall, so it can penetrate further down into the soil. This is a great way to build up meaningful soil moisture.
A perennial with an insect or disease problem should always be pruned in fall, no matter the type. Trim and discard of any infected plant stems to stop an infestation from carrying over into next year's growing season.
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.
Cold, dry winds can strip water from evergreens faster than their roots can absorb it, too. That is why it is especially important to provide enough water in the fall and during dry, warm spells in the winter. Even though they lose their leaves, deciduous trees should also not get too dry in the fall and winter.
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'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.
Most houseplants are tropical plants that can safely grow in a heated home during the winter. They will never survive outdoors in winter unless you live where the temperature stays at least above 50 degrees.
The time of year
There is less light in Winter and the temperature is cooler. This means the plant slows down because photosynthesis is less effective. Providing the room isn't excessively hot, you may reduce watering to just once every two weeks or once a month for some plants over the Winter months.
Water for Plants During Winter
Your plants won't need as much water during their dormancy as they do in the spring and summer, but be sure to water them deeply a few times a month.
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.
The best time to water outdoor plants is in the morning when temperatures are usually cooler. This gives the plants time to absorb the water so they can get through a long, hot day. The second-best time is late in the afternoon or early in the evening.
The best way to tell if your plants need water is to stick your finger about an inch into the potting mix—if it feels dry, break out the watering can.
The best time to water plants is in the morning or evening.
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.