Last word on pruning shrubs:

Late July through Nov. 1 was described as the worst time to prune a boxwood shrub in last week’s article. The reason given was the potential for severe damage at the point where cuts had been made if there was a hard frost or a freeze before new growth/ tissue cells hardened. That risk applies not only to boxwoods but to other trees and shrubs pruned late in the season, as well.

The right time to prune is either while the plant is dormant in November or December (but not when the wood is frozen) or just before or right after the shrub breaks dormancy in spring.Because most woody-stemmed shrubs that bloom in springtime (azaleas and forsythia for example) form flower buds the prior year, it is traditional to delay pruning until after the flowers fade. Flowers on boxwood species have little ornamental value, so time of blossom is not a factor.   

If pruning a number of trees or shrubs that have winter damage, wipe the blades between cuts with an antiseptic to prevent spreading from plant to plant bacteria or disease in decayed tissue. Both a 10-percent chlorine-and-water solution and isopropyl rubbing alcohol (70 percent) are effective disinfectants. I use the alcohol because no mixing is necessary and it doesn’t seem to rust or dull blades on pruners. A fellow Master Gardener tipped me off to how easily alcohol can be applied using a plastic spray bottle. I keep one with my pruning implements.

A good 20-page (free) brochure "PB1619 Best Management Practices for Pruning Landscape Trees, Shrubs and Ground Covers’"can be picked up at your county UT Extension office or downloaded to your computer from the Landscaping sub-section of the Home Garden, Lawn and Landscape link at the right side of the main UT Extension Publication webpage, UTextension.tennessee.edu/publications/

When should ornamental grasses be cut back?

Ornamental grasses can be pruned after they turn brown or wheat-colored in autumn or left standing as a winter landscape feature then cut back in springtime. Spring removal of old ornamental grass stalks and leaves should be timed to avoid injuring the tips of new green growth. In general, cool season grasses are pruned in late winter and warm season grasses around the last frost date for your region.

Warm season grasses change color when air temperatures cool at summer’s end. Prune to leave stalks two or three inches above soil level. Varieties in the warm season category are fountain grass (Pennisetum), hardy pampas grass (Saccharum) and maiden grass (Miscanthus). Cool season grasses stay green longer in autumn and produce new growth very early the next season. If left standing in winter, cut back soon after temperatures stay above freezing. Don’t crop cool season grasses too close. That can harm the crown. Leave about 1/3 of stem height. Included in cool season varieties are ribbon grass (Phalaris), feather grass (Stipa) and Northern Seas Oats (Chasmanthium latifolium). My northern sea oats grow only 24 to 30 inches high in loose clumps. No pruning is required.

I have two types of maiden grass: zebra grass, Miscanthus sinensis ‘Zebrius’ and porcupine grass, Miscanthus sinensis var. Porcupine Grass form tall, tight clumps. Both have lighter markings that make the foliage appear to have horizontal bands of light yellow across a dark green background. Porcupine grass is more upright. Wear gloves and long sleeves when pruning or dividing Miscanthus. Without protection serrated leaf edges can cause cuts and welts. If sections of leaves and stalks are bound together with paper masking tape prior to cutting, each level cut off can go directly to the compost pile after removal.

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Plateau Gardening written by Master Gardeners for gardeners in Tennessee’s Upper Cumberland Region. Contact UT Extension Cumberland County at P.O. Box 483, Crossville, TN 38557 (484-6743) answers to horticulture questions, free publications and to learn about the Master Gardener program. Send email comments or yard and garden inquiries to Master Gardener Rae (MGardenerRae@frontiernet.net).

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