Keep Your Colorado Garden Lush: Essential Winter Watering Guide

Colorado’s unique climate, characterized by dry air, low precipitation, and fluctuating temperatures, presents specific challenges for gardeners, especially during the winter months. While the landscape may appear dormant, plants, particularly trees, shrubs, and perennials, are still alive and need supplemental winter watering to thrive. Understanding the importance of winter watering and how to do it correctly can make the difference between a vibrant garden in the spring and struggling plants that may be more susceptible to disease and insect damage.

Why Winter Watering is Crucial in Colorado

Many people believe that cold temperatures are the primary threat to plants in winter, but in reality, dehydration is often the main culprit. The combination of dry air and minimal snowfall in Colorado means that plants can lose moisture through their leaves, stems, and root systems. This is especially true for evergreens, which continue to transpire throughout the winter. Without adequate soil moisture, plant roots can be damaged, leading to what’s known as “winter kill,” which may not be obvious until the warmer temperatures arrive and plants struggle to emerge. Newly planted trees, shrubs, and lawns are particularly vulnerable, as they don’t have well-established root systems.

The Effects of Winter Drought

A lack of moisture during winter months can have several negative impacts on plants:

• Root damage: Dry soil can lead to root desiccation, weakening the plant.
• Reduced vigor: Plants may be unable to store sufficient energy, leading to poor growth in the spring.
• Increased susceptibility to pests and diseases: Stressed plants are more vulnerable to infestation and disease.
• Delayed spring growth: Insufficient winter water can delay or prevent plants from leafing out in the spring.
• Winter burn: Evergreens can experience browning of needles due to dehydration.

When to Water Your Colorado Garden in Winter

The timing of winter watering is crucial. You’ll want to water when temperatures are above 40 degrees Fahrenheit, and the ground is not frozen or covered in snow. Mid-day is generally the best time to water, as this allows water to soak in before possible freezing at night.

Ideal Timing:

• Frequency: Water one to two times per month during dry periods, particularly when there has been no significant precipitation for about three weeks.
• Temperature: Ensure air and soil temperatures are above 40°F.
• Ground Conditions: The soil should be thawed and not covered in snow or ice.
• Time of Day: Midday watering allows time for water to penetrate the soil before temperatures drop.

How to Water Your Colorado Garden in Winter

Effective winter watering requires more than just turning on your sprinklers. Here’s how to water your garden properly:

Watering Methods

• Hose with Watering Wand: This is the most common method. Use a watering wand or attachable sprinkler to ensure even coverage.
• Soaker Hose: Ideal for slow, deep watering, particularly around trees and shrubs.
• Deep Root Waterer: A specialized tool for reaching the lower roots of trees and shrubs.

Best Practices

• Water Slowly: Allow water to soak into the soil slowly to encourage deeper penetration and prevent runoff.
• Water the Dripline: Focus on watering the area under the outer edge of the plant’s branches (the drip line), where most of the active roots are located.
• Avoid Overwatering: Water to a depth of about 12 inches for trees and ensure the soil is moist, but not waterlogged.
• Use the Cup Method: Place several empty cups in your garden, and water until each has accumulated half an inch to an inch of water to ensure adequate watering.
• Check Soil Moisture: Before watering, use a probe or screwdriver to check soil moisture. If it goes in easily, additional watering may not be needed.

How Much Water to Apply

The amount of water needed depends on the type and size of the plant. Here are some general guidelines:

• Trees: Apply 10 gallons of water for each inch of the tree trunk’s diameter (measured 6 inches above the ground). For example, a tree with a 2-inch diameter needs 20 gallons of water per watering.
• Shrubs: Newly planted shrubs require about 5 gallons of water twice a month. Established shrubs need between 5 and 18 gallons of water, depending on size.
• Lawns: Water until the soil is moistened to a depth of 3-5 inches.

Plants that Benefit Most from Winter Watering

While most plants benefit from supplemental winter watering in Colorado, some are more susceptible to drought injury than others, and require additional attention:

• Newly planted trees, shrubs and lawns: Their roots are not yet established and need consistent moisture.
• Evergreens: Such as spruce, fir, arborvitae, yew, Oregon grape-holly, boxwood, and Manhattan euonymus need winter watering to prevent desiccation.
• Deciduous trees with shallow root systems: Examples include European white and paper birches; Norway, silver, red, Rocky Mountain and hybrid maples; lindens, alders, hornbeams, dogwoods, willows, and mountain ashes.
• Perennials and groundcovers: Those in exposed areas are more susceptible to freezing and thawing.

Plants That Don’t Need Winter Watering

• Cacti and Succulents: These are very drought-tolerant and do not need supplemental watering during winter.
• Native Grasses: Buffalograss and blue grama grass are also adapted to drying out during winter and do not require additional water.

Additional Tips for Winter Garden Care

Beyond watering, consider these additional tips:

• Mulching: Apply a layer of mulch around the base of your plants to help conserve soil moisture.
• Trunk Wrap: Protect the bark of young deciduous trees from sunscald by wrapping the trunks in late October or early November.
• Disconnect Hoses: Disconnect hoses from faucets and drain them after watering to prevent freeze damage.
• Monitor your plants: Keep an eye on your plants throughout the winter and water when dry periods persist.
• Fertilize: Apply fertilizer to lawns in the fall, around Labor Day and Halloween, to help prepare them for winter.

The Benefits of Winter Watering

By diligently following these winter watering guidelines, you can protect your landscape investment and ensure a beautiful and thriving garden in the spring. Remember that proper winter watering is not just about survival; it is also about promoting healthy root development, increasing plant vigor, and reducing susceptibility to pests and diseases. This proactive approach will reward you with a lush and resilient garden that can withstand the challenges of Colorado’s unpredictable climate. By understanding the importance of supplemental watering during the dormant season, you’ll be well-equipped to keep your Colorado garden healthy and vibrant for years to come.