Extension

Courtney DeKalb-Myers, Assistant Extension Specialist in Consumer Horticulture

As the days get shorter and cooler, it might feel like gardening season is over. While we’re certainly nearing the end of the growing season, there are still a few important things homeowners can do now to help their landscapes thrive next spring. Oklahoma’s fluctuating fall temperatures and sudden freezes make some of these tasks especially important.

Continue to Check Trees and Shrubs for Moisture

Recent rains have helped with drought conditions across the state, but many areas are still very dry. It is important to ensure that trees and shrubs continue receiving adequate moisture, even as temperatures cool. Adequate moisture is especially critical for newly planted trees and shrubs, as well as evergreens. Broadleaf evergreens in particular are susceptible to drying out in the winter. Continue checking soil moisture throughout winter, as supplemental irrigation may still be necessary during extended dry periods when the ground isn’t frozen. When irrigating, prioritize watering deeply rather than frequently.

Refresh Mulch Around Vulnerable Plants

Mulch helps protect plants by moderating fluctuations in soil moisture and temperature, something that’s especially beneficial during Oklahoma’s unpredictable fall and winter weather. Organic mulches, like wood chips, leaf litter, or pine straw, break down over time and help promote healthy soils. Aim to maintain approximately 2 inches of mulch around trees and shrubs, but take care to avoid piling it against trunks or plant crowns. Heavy mulch near the base of the plant can cause excess moisture accumulation and potential disease problems. After a killing frost, consider adding mulch around perennial plants to help insulate their root systems from winter temperature fluctuations.

Figure 1. Mulch helps protect plants throughout the winter. Place approximately 2 inches of mulch around trees and shrubs. Mulch around perennial plants after a killing frost. (Credit: Courtney DeKalb-Myers)

Clean Up Selectively, Not Completely

A healthy landscape does not need to be perfectly clean going into winter. When tackling fall cleanup, prioritize removing diseased plant debris and materials that were heavily infested by insects. Leaving healthy perennial stems and seed heads can provide habitat and food for wildlife. Remove heavy accumulations of fallen leaves from cool-season turfgrasses and cool-season annuals, like pansies, so they can continue receiving sunlight and remain photosynthetically active. Light layers of leaves on lawns can also be shredded with a mower, allowing them to break down and return organic matter to the soil. Otherwise, leave the leaves alone. They too can provide habitat for overwintering insects, birds, and other wildlife.

Protect Vulnerable Plants and Irrigation Systems

Freezes can feel sudden in Oklahoma. Pay close attention to the forecast to prepare for necessary protective measures. Before freezing temperatures arrive, disconnect and drain garden hoses, protect outdoor faucets, and make sure irrigation systems are properly winterized. Tender container plants should also be moved indoors if low temperatures are forecasted. Less cold-hardy vegetables in the garden can also be protected with frost cloth or a lightweight blanket to help extend the growing season.

Put the Pruning Shears Away (for Now)

Late fall is generally not the time to prune landscape plants. Pruning while plants are still actively growing can encourage tender new growth that may be damaged by subsequent freezes. Dead, damaged, or hazardous branches can be removed as needed, but most major structural pruning of deciduous trees and shrubs is best saved for the dormant season. It’s also important to note which plants within the landscape flower in the spring. Plants like forsythia, flowering quince, lilacs, bigleaf hydrangeas, and oakleaf hydrangeas should be pruned after flowering, as pruning now can remove the flower buds.

Preparing the landscape for winter doesn’t have to mean an extensive list of chores. A little attention to moisture, protecting from freezing temperatures, and knowing what to leave alone can go a long way toward keeping the landscape healthy. Taking care of these few tasks now can help set the stage for a successful growing season next spring.