Do you need to water your trees and plants in the winter?
While the warm, sunny weather this winter has made for nice days to take a walk in the park, the dry conditions are tough on your trees, plants and grass.
That’s why it’s important to give them some water during long dry spells.
Winter watering is something many of us forget to do and may not understand why it’s necessary. So we asked Deryn Davidson, a sustainable landscape specialist at CSU Extension, for some help.
You can watch the full interview in the video above; her responses to common questions are below.
We often forget about watering in the winter months, when should you do it?
Great question. And you’re right, it’s easy to forget. In Colorado, winter watering is really about watering during extended dry spells. If we’ve gone three to four weeks without measurable moisture, especially in a warm, dry winter, that’s a good signal that plants may need supplemental water.
Does the occasional 2–3-inch snowstorm provide much moisture?
They do help a little, but usually not as much as people think. Light snow often evaporates or blows away before it really soaks into the soil, especially when the ground is frozen. Those storms are great, but they usually don’t provide enough deep moisture for trees and shrubs during long dry periods.
Aren’t trees, plants and grass dormant over the winter?
They are dormant and not actively growing, but they’re still alive. And their roots still need moisture, especially newly planted trees and plants. Evergreen trees and shrubs, in particular, continue to lose water through their needles or leaves all winter long. Without occasional precipitation or watering, they can become stressed.
Does location in the yard play a role?
Yes! Trees and plants that are in wind-prone parts of the yard and ones in south-facing areas dry out faster, so they typically need more water than ones in protected or shaded areas.
What kind of damage can happen during a long dry spell without watering?
One of the most common issues we see is called “winter desiccation,” which is basically a fancy term for “drying out.” You’ll notice browning needles on evergreens, dieback on shrubs, cracked bark, or even plant death in severe cases. Lawns can also come out of winter weaker, which makes them more vulnerable to weeds and disease in spring.
When is it OK to water?
There are a few key rules when winter watering is safe and effective:
- Water on a day when it’s above 40 degrees.
- Make sure the ground is not frozen.
- Water early enough in the day so moisture can soak in before temperatures drop again.
What are two big reminders when you’re done watering?
First, disconnect your hose from the spigot to prevent freezing and pipe damage.
Second, don’t turn on your in-ground sprinkler system in winter. Stick to hand watering or hose-end sprinklers only.
How much water do trees need during dry spells?
A good rule of thumb is about 10 gallons of water per inch of trunk diameter during a dry period. Most established trees may only need this once a month in winter if it’s dry.
Do you need to think about newly planted trees vs. established trees differently?
Yes, newly planted trees need much more attention. Their root systems are smaller and haven’t spread out yet, so they may need watering every two to three weeks during really dry spells, even in winter. Established trees may only need watering every 4-6 weeks.
What are some methods to water a tree?
Slow and deep is the goal. A hose set to a trickle, a soaker hose, or a hose-end sprinkler all work well. You want the water to soak into the soil and not run off the surface.
Where should you water the tree?
Water at the dripline, which is the area under the outer edge of the tree’s canopy. That’s where the rain falls and the most active roots are located. Do not water established trees close to the trunk.
How about plants, how much water do they need?
Similar to trees, just on a smaller scale. Newly planted shrubs may need watering every two to three weeks during dry periods. Established plants usually only need water during extended drought conditions.
How do you water them?
Hand watering works great, just apply water slowly at the base of the plant so it can soak in deeply. You can form a basin with the mulch to hold water in for that slow soak. You can also fill a 5-gallon bucket and pour that on slowly, so you know more accurately how much water you’re putting down.
What about water-wise plants, do they need extra water?
Water-wise or native/xeric plants are very drought-tolerant, but even they can benefit from occasional winter watering, especially during unusually dry winters or if they were planted within the last year or two.
Do you need to water Kentucky bluegrass in the winter? What are the benefits and what’s the best way to do that?
It’s not always necessary, but winter watering can help prevent crown dehydration, especially on sunny, south-facing lawns. If we’ve had a long dry spell and conditions are right, watering once a month can help the lawn green up faster in spring. It can also potentially help keep turf mites at bay as they love a dry winter lawn.
Use a hose-end sprinkler on a warm day and apply water evenly, just enough to moisten the soil, and not enough to create runoff. You can set up plastic cups and run the sprinkler until you’ve got about half an inch of water in the cups.
Find more landscape tips on CSU Extension's website.