Wintry weather finally came! After a very dry fall we are excited to get some seasonal temperatures and a bit of snow on the mountains and in the valley. This has bumped the Arkansas River basin up to 58% of average snowpack for this time of year, so we are still very dry.
The CSU Extension office and our Colorado Master Gardeners get a lot of emails, calls and questions about tree care, and one of the most common issues we see is from lack of winter watering. After a fall with very low precipitation and unseasonably warm temperatures, winter watering of trees is even more critical. Water your trees, shrubs, perennials and lawns if there are more than two weeks with no rain and no snow cover.
When should I water plants in winter? Water around midday on a day when the temperature is above 40 degrees Fahrenheit, to allow enough time for the water to soak in before freezing. Ice capping a lawn for over a month can suffocate the plant roots.
How often? I generally water once or twice a month, but err on the side of more water if your trees or grass are newly planted.
Where should I water the plants?Established trees have roots that mirror the tree, so water within the drip line, or the circle of where the tree branches spread, not all right at the trunk. Newly planted trees are the most susceptible to injury from lack of winter watering. It takes about one year per inch of trunk diameter at planting for a tree to get established. This means, if you planted a larger tree with a 3-inch diameter trunk this year, it will take three years to be established.
How much should I water? Trees generally need at least 10 gallons per inch of trunk diameter at each watering to survive. So our example tree that is 3-inch diameter would need at least 30 gallons, twice a month. For a newly planted shrub, apply 5 gallons of water twice a month; once a smaller shrub is established, 5 gallons of water once a month should be fine. Larger shrubs over 6 feet tall should be given 18 gallons of water a month. If we have had a little bit of rain/precipitation but not a lot, you can decrease these amounts some.
How else can I make sure my trees have enough moisture?Mulching your trees and shrubs with woodchips can limit moisture loss to sun and wind when there is no snow cover. But don’t mound the woodchips up around the trunk! I mulch in a doughnut shape but don’t have any mulch up against the trunk. Leaves work well also if you are sheltered from the wind, or underneath woodchips. Otherwise your leaf-raking work will probably most benefit your neighbor downwind.
Other winter tree care tips?Colorado has intense sun, which comes in at a low angle in the winter and can cause frost crack and sun scald. Thin-barked trees like honey locust, maple and linden will be protected if you put on a tree wrap up their trunk – just make sure to remove it in the springtime. Pruning is best done in the late winter. Chaffee County Extension will host another class on pruning fruit trees in February or March. For updates on this and other gardening workshops and events, follow us on Facebook at Chaffee County Extension.
Any other concerns about tree health?We can help you best if you bring or send us photos of the tree in question. Ideally a couple of any issues or damage you see close up, whether that is an insect, sap or pitch, or discolored or damaged leaves or needles, and then a couple of photos of the whole tree to see any pattern to the damage. Send them to coopext_Chaffee@mail.colostate.edu.
If you have more questions, our Master Gardener volunteers will be at the Foodshed Alliance Winter Farmers Markets every Saturday, 10 a.m.-1 p.m. at Chaffee County Fairgrounds through Dec. 20. While you’re there, the Winter Farmers Market Food Drive is gratefully accepting donations to distribute to the little free pantries across Chaffee County.
You can also bring your gardening questions to the Chaffee County Extension office, in the newer log cabin at 185 Quigot Court, or the far northwest corner of the fairgrounds. We are open 7:30 a.m.-5:30 p.m. Monday to Thursday to help answer questions on gardening, hand out well water tests, help troubleshoot what bug is affecting your trees and more.
Monica Pless is director of the Colorado State University Extension office in Chaffee County.
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