You may be ready to put away the garden hose and watering can for the season, but not so fast! Many garden plants actually benefit from a little more TLC at this time of year. “Fall watering might be one of the most overlooked garden chores,” says Natalie Carmolli, shrub expert with Proven Winners ColorChoice Shrubs. “But it’s the easiest thing you can do to give your plants what they need to sail through winter.”
It's also a good idea to add mulch to your beds and new plantings before winter, if you haven’t done so already. “A 2-3 inch layer of shredded bark or wood mulch helps hold moisture in the soil, keeps soil temperatures more even, and protects roots through freeze and thaw cycles,” says Carmolli.
The good news is that you can pull back on other garden chores now. It’s too late to fertilize plants in fall because you don't want to push tender new growth right before winter. You also should not be cutting back shrubs this time of year, unless there’s a broken branch that needs removed. “Late season pruning can encourage new growth too, and some shrubs, like many hydrangeas, are already setting next year's flower buds,” says Carmolli.
Here's what you should know about fall watering:
Why you should keep watering in the fall
While you’re focused on cleaning up leaves and doing the last mow for the season, plants aren’t necessarily done growing. “A lot of people see the leaves turning and falling from trees and shrubs and figure the plants are going to sleep and the growing season is over, but there is still significant growth happening below ground,” says Carmolli. “Even after top growth slows down, roots will continue to grow until the soil temperature drops to about 40°F.”
In fact, by watering plants well into fall, you’re giving them an edge on harsh weather conditions ahead. “Plants that go into winter well-hydrated are better prepared to handle cold, drying winds, and frozen ground,” says Carmolli.
Understanding the life cycle of your plants also will help you decide why you need to water. “New plants and seedlings have shallow roots that need the soil to remain moist in order to survive, while mature plants have extensive root systems that reach far into the soil to gather deep water stores,” says Stephanie Rose, author of The Wild & Free Garden and founder of Garden Therapy. Thus, young plants naturally need more support than established ones.
What plants should you keep watering in the fall?
Here are the plants that benefit the most from fall watering:
Newly-planted shrubs and perennials
“Anything that went in the ground this season won't have well-established root systems yet, so they can't reach very far for moisture,” says Carmolli. “They're counting on you! The later the planting, the more they need regular water to get settled before winter.”
Evergreens
All plants lose water through their leaves through a process known as transpiration. Plants that drop their leaves in the fall go dormant, and transpiration nearly stops for the winter. “But evergreens like boxwood, holly, rhododendron, arborvitae, and yews keep their leaves or needles all winter, which means they keep losing moisture, too,” says Carmolli. Once the ground freezes, they can’t pull up more water—which is what causes winter burn and browning that you often see in early spring. So, a deep watering before the ground freezes is the best prevention.
Evergreens in exposed spots
Evergreens planted along a windy corridor or on the south or west side of your house lose moisture even faster. “This is because the winter sun warms their foliage on bright days, and wind pulls moisture away, so they dry out quicker than evergreens in more sheltered spots,” says Carmolli. Give these plants a good, deep soak before the ground freezes.
Shrubs and perennials in containers or raised beds
Because they’re sitting above ground, containers and raised beds dry out faster than plants in the ground. If you’re overwintering a perennial or shrub in a container, remember it’s dormant, not dead, so the roots still need moisture. “If you’ve moved containers into an unheated garage or shed, water them every few weeks, just enough to keep the soil from drying out completely. The same goes for containers tucked under eaves or up against your foundation, where rain and snow can’t easily reach them,” says Carmolli.
How often should you water your garden in the fall?
It can be tough to know how much water your plants need, but a good estimate is to stick with about an inch of water per week, from rain or from you. “If you haven't had a good soaking rain in a week to 10 days, it's time to water,” says Carmolli.
Do a deep, slow watering, rather than a quick sprinkle, so water actually gets down to the roots. A soaker hose or letting the hose trickle at the base of the plant works great. If you’re not sure whether or not your plants need it, stick your finger a couple of inches into the soil. If it's dry, water. Also, water in the morning or midday, so plants aren't sitting wet overnight as temperatures drop, says Carmolli.
Unlike summer, when you may need to water daily—or even twice a day for container plants during heat waves—you will water far less frequently. “Cooler temperatures and shorter days mean that far less water is leaving the soil, so fall gardens can be watered much less often,” says Rose. Also, be careful not to overdo it, so that the soil becomes waterlogged.
When you can stop watering in the fall?
Once the leaves have fallen and you’ve had a frost or two, you may be tempted to stop watering. Not yet! “Keep going until the ground freezes,” says Carmolli. “In a lot of areas, that's late November or into December, but it really depends on where you live and the year you're having.”
It’s fine to stop once the soil is frozen because water will just run off or sits on top. “One last deep watering right before the freeze is a great send-off, especially for evergreens,” says Carmolli. “In warmer zones, if you get a stretch of mild, dry weather where the grounds thaws a bit, it doesn't hurt to give evergreens an extra drink.”
Arricca Elin SanSone is a writer, editor, and content creator who specializes in lifestyle and gardening. With a background in health reporting, she applies these same research skills when writing about the science of growing things. She trials new plants in her expansive garden, and her houseplant collection consists of 60+ varieties. Arricca has written thousands of articles for publications such as Country Living, House Beautiful, Good Housekeeping, Prevention, VERANDA, Southern Living, and more. She’s happiest when digging in the dirt, baking, or spending time with the people and dogs she loves.
