Tree care services 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 article covers the effects of drought on trees, the importance of dormant season watering, and how proper fertilization can help trees thrive during drought in Colorado.
How Does Drought Affect My Trees?
Colorado has been experiencing very dry winters and it’s 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 summer, but what can happen to trees when they experience drought during the winter months? Here are the primary concerns from the Colorado State University Extension:
Sunscald
- 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 dormant season watering and tree wraps can help prevent sunscald damage this winter.
Drought Injury
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.
Dehydrated leaf or branch tissue occurs when water is lost through leaves and can’t be replaced through the roots. This is what causes a drought injury. Environmental factors that cause drought injury include:
- dry winters
- low relative humidity
- wind
- soil with high salt concentrations
- restricted root growth from too much water and compacted soil
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 react the same to drought. 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 types that you need to keep a close eye on:
Deciduous Trees
Deciduous trees suffer from leaf scorch due to 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 happens when water is lost through the needles and because the soil is dry, they don’t get replaced by roots. 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 to 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
- The buds can be examined for this. A red color change might also suggest a bark beetle infestation or a root disease condition.
Dormant Season Watering Tips During Drought
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 can hurt a lot!
Excessive watering can cause a tree to develop fungal diseases, root rot, and even girdling roots. Trees that are constantly wet are more susceptible to insect pests. Overwatering woody plants is a frequent problem in Colorado, especially in irrigated turf grass regions. Unfortunately, trees do not display symptoms of water-logged roots until sometime after the overwatering has occurred.
Proper Dormant Season Watering
The best way to protect your trees from stress and drought damage with tree care services is proper dormant season 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:
- Sprinklers
- 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 knee height. As a general rule in Colorado, apply 2 gallons of water per diameter inch of the tree, every two weeks between October and March. For example, a three-inch diameter tree needs six gallons per watering.
Here are some additional guidelines and tips from the Boulder Parks and Recreation Department to keep your trees hydrated and healthy:
- Check soil moisture levels around the dripline of the tree to determine how much water you’ll need. 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. Don’t 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.
- 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 our customers, just give us a call.
Why Dormant Season Watering Is so Important in Colorado
Most people are aware of the importance of watering their plants during the summer, but many do not realize that the best tree care practices include watering 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 stay happy and healthy all year long.
We recommend adding a good watering and fertilizing routine to your home tree care services. 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.
Fertilization Tips During Drought
Denver is a desert climate, which means your trees are starving for nutrients! Subsequently, this nutrient boost is key to your trees’ long-term health. Your trees will be less susceptible to disease and insect infestations, as well as potential breakage.
What Feeds Your Trees
There are several micronutrients that play a big role in boosting a tree’s immunity. Zinc, iron, and boron are a few of the key micronutrients that help keep your trees in fighting shape to combat pests and diseases. The key macronutrients in fertilizer are nitrogen, phosphorus and potassium. Finding a fertilizer with these ingredients is important because they will go a long way toward boosting immunity. The three most common types of fertilizer applications are spike, granular, or liquid.
Compost is a great source of these micronutrients, but often trees require a cocktail of macronutrients and micronutrients. Arborists are able to determine the right combination of fertilizers and application for the trees on your property.
Should You Feed Your Trees?
There are a few points of caution when considering fertilizing your trees:
- Too much fertilizer can further stress your drought-stricken trees.
- Fertilizer should be applied during spring or fall.
- Do not fertilize on frozen ground. The soil is not able to absorb any of the nutrients in the fertilizer when it is frozen.
Proper Tree Care Is Crucial During Drought
With a little finesse and attention to detail, there are many opportunities to boost the health of your trees during the driest of seasons. By understanding what happens to your trees during drought and responding with the correct care, you will be able to assist your trees through the stress, and set them up for success during their growing period.
Don’t let drought damage your landscape. Use these tree care tips or contact our friendly expert team for help with customizing winter tree care services!
