Though December traditionally brings weather conditions during which outdoor plants enter winter dormancy, there are still many considerations to act upon in the landscape.  Due to the diversity of plantings and locations in the state, some of the following will apply now and others in future years.

Winter Watering

A good soaking - about 12 to 18 inches deep - before the onset of freezing soil temperatures helps keep roots hydrated during a long period of time without the opportunity to moisten them.  If they enter the winter in a dehydrated state, they’ll likely wither and retract, weakening the plant overall.

Related to winter watering, the most common questions that Extension Horticulturists and Arborists get are:

                Should I water my trees and shrubs before winter?

                Which plants are most important to water?

                Which watering devices are best?

Should I water them?  The best way to answer this question is to test the soil for moisture, as there is no way to tell by looking at the soil surface.  Fortunately, it’s easy to check for soil moisture; either use a long screwdriver or soil probe and push it in near the trunk, 4-5 feet away from the trunk and at the drip line of the branches.  If only dry soil or no soil at all sticks to the blade after pulling it out, the soil is dry and in need of water.  As well, if it takes a fair amount of force to push the screwdriver into the soil, the soil is likely to be drier than desirable.  A second simple method is to dig a small hole in the same location.  Feeling the soil will provide a good sense of moisture, whether it’s dry and crumbly, moist and sticky or somewhere in-between.

Trees, Shrubs and Perennials to Focus On – Plants installed in 2023 and 2024 are the ones at most risk of damage from dry soils over winter.  Perennial flowers such as coral bells, cranesbill, ligularia, ginger, baptisia, anemone and bleeding heart should be checked for soil moisture as well.

Devices to use – A good watering tool is one that delivers the needed amount slowly, thoroughly and over the top of the roots.  Tree roots spread out widely, while most perennials have a rounded, heart-shaped root system directly under the crown of the plant.

A final note on winter watering - Be sure to disconnect the hose and watering device from the outdoor spigot after the water is applied.  Failure to do so will result in damage to the plumbing and an expensive repair bill.

Anti-Desiccants

Products as Wilt-Pruf, Transfilm, Vapor Guard and MoistureLoc act to cover the leaves of evergreen trees and shrubs with a thin “horticultural wax”, a procedure that has pros and cons.

Pros – reduces moisture loss from the needles and leaves during winter and subsequent browning of needles/leaves.  In some cases, the stems can be affected also, resulting in the dieback of several inches of previous year’s growth. Using anti-desiccants can help reduce overall dieback in the spring.

Cons – reduces photosynthesis and respiration during winter, resulting in a general weakening of the plant.  The plants that are traditionally treated (arborvitae, holly, Oregon grape holly, boxwood) are often weak enough already due to being in Nebraska winter weather; adding stress from the application of an anti-desiccant may not be advisable.

Usage Tips and Techniques for Anti-Desiccants – First and foremost, read and follow all label instructions.  Just like pesticides, each product is designed to work in a certain way.  In some cases, the active ingredients work better for one plant than another and should be applied under specific conditions.  In most cases, the air temperature at the time of application needs to be above freezing with enough time remaining afterwards to allow for the product to dry thoroughly on the leaf.  To limit the possible negative effects of their usage, consider applying them only to the sides of the plant most exposed to the sun and wind.  Lastly, since these products are wax-like, it’s recommended to use warm to hot water to clean out the sprayer after application; if cold water is used, the product will harden inside and render the sprayer useless for applications of other products in the future.

Other Pre-Winter Management Techniques for Woody Plants

Mulch – After a thorough watering, a 2–4-inch layer of wood chip mulch applied over the roots will greatly reduce evaporation and moisture loss from roots and root hairs.  It’s important to place mulch 6 inches away from the trunk and extend it 4-6 feet into the landscape for avoidance of damage from voles, mice and rabbits and maximum benefit for moisture retention.

PVC trunk columns – To avoid damage to tree trunks from sunscald and critters, a solid column can be installed.  Hard plastic and vinyl materials provide the best protection.  Light colored products will reflect the winter sun, keeping the temperature cool and stable.  They should be installed in late fall/early winter and removed in early spring.  Mesh columns can be used as well.  Though they do little to prevent sunscald, they are quite effective against the chewing of voles and mice.