The Homeowners Column

The Homeowners Column

Flooding Causes Problems for Landscape Plants

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

The monsoons are continuing. The plants on my porch yearn to be planted. Their legs may be cramped but at least soggy bottoms are not a problem.

What can we expect from our landscape plants with all the rain? With garden flowers, root rot may develop. Leaves may turn yellow to brown and drop prematurely usually starting with older leaves and moving up the plant. Plants may be stunted or may wilt easily on a warm day even when plenty of water is available. Plants may eventually die.

When removing dead plants, look at the roots. If they are brown or black and slippery instead of white and firm than root rots may have been the cause of death.

Garden flowers show symptoms quickly, but woody plants may take a year or so for symptoms to become apparent. How well a plant survives water logging depends on the type of plant, age, size and general health.

The type of soil, how long the area is flooded, depth of the water and whether the water is flowing or stagnant will also effect plant survival.

Symptoms in woody plants include leaf yellowing, red or purple color (in pear and other plants), browning of leaf margins, stunting of growth, twig dieback, absence or diminished fruit yield, root death, wilting, leaf drop and downward bending of leaf petioles. Plants stressed by too much water are also more susceptible to attack by insects and diseases.

Plants with water injured roots may also die or experience twig dieback later from drought stress. As soils dry, the reduced root system can't keep up with the water needs of the plant.

Woody plants that tolerate waterlogged soils include green ash, bald cypress, redtwig dogwood, eastern larch, red maple and black and sandbar willows.

Intermediate tolerance includes eastern arborvitae, arrowwood and American cranberry bush viburnum, white ash, Japanese barberry, river birch, eastern cottonwood, sweet gum, hackberry, bur and pin oaks, sycamore and pussy willow.

Tree and shrubs intolerant of wet conditions include basswood; American beech; gray, paper and European white birch; eastern red cedar; crabapples; flowering dogwood; forsythia; redbud; shagbark hickory; American holly; saucer magnolia; northern red and white oaks; peach; red and eastern white pine; blue, Norway and white spruce; tuliptree; black walnut and yews.

Once damage occurs there isn't much we can do besides basic tender loving care such as watering plants during drought periods. Don't be too quick to remove plants showing symptoms. It may help to rake mulch off plants in wet areas until soil partially dries then hope for better weather.

Tree Walk originally scheduled for May 11 has been rescheduled for Saturday June 15 at 10:00 am starting on the corner of Victor and University Avenue in Champaign.

U of I Extension Master Gardeners of Champaign County present the Great American Garden Walk on Sunday June 16 from 10-5, rain or shine. Gardens this year include water features, koi pond, victory garden, country gardens and cottage gardens.

Tickets are $8 in advance and $10 on the day of the walk at the Idea Garden. Tickets also available in Champaign at the University of Illinois Extension office at 801 North Country Fair Drive (217) 333-7672, Abbott's Florist, Grapevine Creations, Greenview Nurseries, Rick Orr Florist and Prairie Gardens. In Urbana purchase tickets at Country Arbors Nursery, FS Farmtown, and English Hedgerow and each Saturday at Urbana Farmers Market. Tickets are also available at English Hedgerow and Main Street Mercantile in Mahomet, Pages for All Ages Bookstore in Savoy, Kleiss Nursery in Tolono, Steeple Gallery in Monticello and Danville Gardens in Danville.

All Garden Walk proceeds go toward Master Gardener projects in Champaign County such as our Idea Garden on South Lincoln.

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