Tree care during drought can be difficult, but if you know how to do it properly, your Colorado trees will be much more likely to survive. This blog post covers the effects of drought on trees, the importance of winter watering, and how proper fertilizing can help trees thrive during drought in Colorado!
How Does Drought Affect My Trees?
Colorado is experiencing a very dry winter and it is important to remember that trees are still in need of water during the winter months, even when leaves have fallen. If your Colorado trees receive too little or no water during this time, they can become stressed and be more susceptible to pests and diseases that cause severe damage before spring comes around again.
We mainly associate drought with winter, but what can happen to trees when they experience drought during the winter months? Here are the primary concerns outlined by the Colorado State University Extension:
- Sunscald occurs during cold, bright days in midwinter.
- Direct sun rays heat south-facing branches and southwest sides of tree trunks. This raises bark temperatures above freezing and causes some cells to become active.
- After sunset or with changing weather conditions, the bark experiences a sudden temperature drop, killing the activated tissue.
- Sunscald can occur on the north side of trees and shrubs due to reflection off white or light-colored structures immediately adjacent to susceptible woody plants.
- Bark in the affected area may initially turn red, orange, yellow, or some other hue not consistent with normal bark color. The bark then may crack, become mushy, or slough off in patches revealing dead tissue underneath.
- Sunscald occurs more frequently on thin-barked trees such as aspen, birch, cottonwood, fruit trees, honey locust, linden, mountain ash, maple, and willow.
Proper winter watering and tree wraps can help prevent sunscald damage this winter.
Trees need water to survive. They absorb both rain and moisture from melting snow, but how much they require varies depending on tree species and age.
A drought may result in younger trees dying more quickly than older ones because of current environmental stresses or previous injury that makes them less able to cope with additional stressors.
Drought injury is dehydration of leaf or branch tissue that occurs when more water is lost through leaves than can be replaced through the roots. Environmental factors that cause drought injury include:
- dry winters
- low relative humidity
- soil with high salt concentrations
- restricted root growth from too much water and compacted soil
How serious is drought injury?
Damage from leaf scorch, winter drying, and drought injury cannot be reversed. Drought injury can be minor and cosmetic in some cases, but in others, it can result in severe stress and damage to the tree.
Which Denver Trees Are Most Susceptible to Drought Damage?
Not all trees are affected by drought in the same ways. Some Denver trees are more at risk than others, and it is important to learn which trees on your property could be under stress. Here are the species that you need to keep a close eye on:
- Deciduous Trees
Deciduous trees suffer from leaf scorch when they are adversely affected by drought. This looks like tan or dark brown areas of discolored tissue between leaf veins or along leaf margins. During winter drought, freezing of deciduous tree roots can lead to leaf scorch the following summer.
- Evergreen Trees
Winter drying of evergreens results when water lost through the needles can not be replaced by roots because the soil is dry. It often results from rapid temperature changes associated with warm, dry winds in late winter. Here are some pertinent facts:
- Symptoms usually appear first on the south or southwest side but can develop throughout the tree.
- Affected fir trees’ needles generally turn yellowish, although they can also change color from red. Spruce and pine needles become golden to brown before turning crimson.
- Discoloration begins in the outermost branches and works its way down the needle. In severe situations, discoloration spreads rapidly and uniformly throughout the entire needle.
- In early spring, a change in the color of needles may indicate winter dehydration damage; new spring growth is seldom affected. The buds can be examined for this. A red color change might also suggest a bark beetle infestation or a root disease condition.
Wondering if any of your trees are at risk? Contact one of our expert arborists for a consultation today!
Winter Watering Tips
Just as with people, plants need water to survive. The amount of water a plant needs depends on the type of plant, how dry it is, how windy it is, how much sun the plant gets, what kind of soil the plant is in, and how wet or dry the surrounding air is.
During times of drought, many homeowners go overboard and end up overwatering their trees. After all, what could it hurt? Turns out, it could actually hurt a lot!
Excessive watering can cause a tree to develop fungal diseases, root rot, and even girdling roots. Trees that are constantly wet also become more susceptible to insect pests. Overwatering woody plants is a frequent problem in Colorado, especially in irrigated turfgrass regions. Unfortunately, trees do not display symptoms of water-logged roots until some time after the overwatering has occurred.
Proper Winter Watering
The best way to protect your trees from stress and drought damage is proper winter wintering. We’ll cover the correct tools and supplies needed, and how to accurately gauge the amount of water your plants and trees need.
How exactly do you go about watering your landscape in the wintertime? The Colorado State University recommends the following methods for watering trees:
- Deep-root fork or needle
- Soaker hose
- Soft spray wand
For best results, apply water to many locations under the dripline and beyond if possible. This will help the root system absorb the water more efficiently. If using a deep-root fork or needle, insert no deeper than 8 inches into the soil. This is the sweet spot!
How much water is enough? Start by measuring your tree trunk. Use a ruler to measure your tree’s diameter at 6″ above ground level. As a general survival rule, apply 10 gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree needs 20 gallons per watering.
As discussed above, caring for and watering evergreens and deciduous trees this winter is a top priority! Follow these guidelines and tips from the Boulder Parks and Recreation Department to keep them hydrated and healthy:
- Water your deciduous and evergreen trees up to two times a month between October and March.
- Check soil moisture levels around the dripline of the tree to determine how much water is needed. To accurately determine soil moisture, dig down at least 4-6 inches.
- Water during the day when temperatures are above 40 degrees to allow the water to soak in before freezing night temperatures. Do not water if the soil is frozen. Hand watering, soaker hose, or drip applications are allowed up to two hours per area with no day or time restrictions.
- Soaker hoses, soil needles, or hoses with a soft spray attachment can be used to water trees in the winter. Do not turn on your irrigation system to water your trees.
- How much water your tree should receive depends upon the tree size. A general rule of thumb is to use approximately 10 gallons of water per inch of trunk diameter for each watering. Measure trunk diameter at knee height. General formula: Tree Diameter x 5 min. = Total Watering Time
- The most important area to water for deciduous trees is within the dripline (from the trunk to the outer edges of the tree’s branches). For evergreens, water 3-5 feet beyond the dripline on all sides of the tree.
- Maintain mulch 4 inches deep around trees and shrubs to retain moisture. Pull mulch back from the tree trunk. Mulch is available free to Boulder residents from Western Disposal.
Pros of Winter Tree Care
Most people are aware of the importance of watering their plants during the summer, but many do not realize that it is also beneficial to water them during the dormant season. Root growth ceases during dormancy and is particularly robust in newly planted trees and shrubs. Young plants and trees that receive continuous winter watering survive longer and avoid dehydration and mortality.
Droughts are a regular occurrence in the Front Range, and there isn’t always enough snow cover to keep the soil wet. Denver is semi-arid naturally, relying on irrigation to maintain many of the lovely trees that make up its vistas. Don’t expect nature to provide adequate water for your plants and trees this season. Doing your part will help keep your trees happy and healthy all year long.
The best thing you can do is get in a good watering and fertilizing routine. In residential landscapes, trees may not get all the nutrients they need. This means that it is often necessary to apply fertilizer around trees to provide the essential elements required for healthy growth. The right fertilizer can also help reduce stress on trees caused by drought.
The healthier a tree is, the more immunity it will have when it comes to battling pests and diseases. Fertilizer essentially acts as a booster for your trees, providing the nutrients it can’t access directly from the soil.
Trees require a cocktail of macronutrients and micronutrients, and it is best left to the experts to determine exactly what the right combination of fertilizers and application process would be for your trees. Our experienced arborists will craft a custom fertilization plan based the health of your specific trees. Our fertilization program begins in the spring and now is the time to get on our schedule.
Don’t let drought damage your landscape this winter. Contact our friendly expert team for help with customizing a winter watering schedule and fertilization plan today!