Archive for Thursday, December 6, 2007

The green thumb

December 6, 2007

Ever since daytime temperatures dropped, my skin has been drying out. I use hand lotions, facial moisturizers and lip protectants, and I consume as much water as I can.

Plants are a little different -- no lotions and protectants, but all perennial plants need water to survive winter. Plant tops are dormant, but plant roots continue growing below the soil surface.

Plants that receive inadequate amounts of moisture are damaged and exhibit symptoms the following spring. The plants most at risk of winter desiccation are evergreens and turfgrasses.

Evergreens lose water as dry winter winds wick moisture away from the needles. On warm sunny days, water also evaporates quickly. When roots cannot keep up, needles dry out completely and die.

The injury is usually worse on outer branches and in exposed sites. If a tree is near a building or structure that reflects heat onto the tree, damage will likely be worse on the side nearest the structure.

To prevent winter desiccation, mulch evergreens in a minimum 3-foot diameter circle. Use organic mulch such as shredded bark. White rock and lava rock reflect heat that adds to winter injury. Pay special attention to newly planted trees and shrubs with root systems that may not be able to support the plant for the winter. Choose trees from local sources that are adapted to Kansas weather, and keep plants healthy the rest of the year.

Water when the soil is dry and temperatures are above freezing. Sprinkling the soil surface will not provide enough water to the plant roots. The best way to water trees and shrubs is to soak the ground slowly.

I like to just barely turn the hose on and leave it running for a few hours near the base of the plant. Soaker hoses and sprinklers also work well to saturate the soil around the plant.

Turfgrasses show less damage than evergreens and recover more quickly, but damage still occurs. Again, warm sunny days and dry winter winds wick away more moisture from the leaves than the roots provide.

Good management practices during the growing season lessen the chances for winter dehydration on turf.

Allow turf to harden off naturally. Reduce irrigation as temperatures drop, and avoid overfertilizing, which encourages top growth. Remove thatch on a regular maintenance schedule (preferably yearly in September) as heavy thatch prevents water from getting to plant roots. Raise mowing height and test your soil to determine fertilizer needs.

Spot-water newly planted and stressed turf over the winter. Grass seed that germinated late in the season probably does not have enough roots to support the plant without extra water. Soak the soil slowly rather than just sprinkling water on the soil surface.

Snow cover insulates plants and plant roots and provides moisture when it melts.

I am watering my viburnums and boxwoods to keep them from drying out, and when I finish, I'll go inside and put on another layer of moisturizer.

-- Jennifer Smith is the Douglas County Extension Agent--Horticulture for K-State Research and Extension. She can be reached at 843-7058 or

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