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MASTER GARDENER COLUMN:Tips for curbside gardening

Mary Lou Marchand

Weeds. Mowing. I don't mind mowing until I get to the curbside. The sand and salt the plow throws on that area during the winter often leaves us with a problem area that is more grit than soil, more weeds than grass. How to improve the area has led me to look at the boulevard or street-side garden concept.

I thought about what plants would work best and if the city had any special regulations such as plant height and how to best cope with the sand and salt. Learn where the various underground utilities such as water, gas and electricity run before digging, especially if shrubs are part of the plan.

The boulevard is a harsh home for plants. It's hot and dry, plus de-icers and snow piles can stress plants. Regular soil tests will help identify any soil problems that need to be corrected. Pick your favorite method for preparing the area for planting. A no-dig plan using newspaper and wood chip mulch is one option. Amending the soil with compost and peat is another.

Keep in mind that plants closest to the curb will probably suffer the most from sand and salt or other de-icers. A 1 to 2-foot strip of mulch by itself or planted with annuals, or a mower's width of grass to provide some distance from the street for the perennials. I think I'll opt for the mulch.

The biggest challenge for me was finding herbaceous perennials with a fairly high tolerance for salt and hot, dry conditions. I was pleased to learn that good variety was possible. Dianthus, euphorbia, baptisia, Stella d'Oro daylily, lupine, sundrops or evening primrose, penstemon, creeping phlox, phlox, various sedums, lamb's ear, gaillardia (blanket flower), candytuft, catmint, coral bells, native asters, black-eyed Susan, hostas, artemisia, yarrow and armeria (sea pink or thrift) allow for an interesting mix of plants. Unfortunately, there is not space to talk about the salt tolerant shrubs.

To the perennials, add some attractive ornamental grasses. Karl Foerster Reed grass (Calamagrostis xacutiflora), blue oat grass (Helictotrichon sempervirens) and switch grass (Panicum virgatum), and Elijah Blue Fescue are among ornamental grasses with salt tolerance.

Include some bulbs for early spring bloom. Annuals will extend the season for the boulevard garden, just as for any other border. Since most perennial borders take up to three years before looking the way we want them to, annuals such as wave petunias will fill the empty spots until the perennials grow to a mature size.

When planning a boulevard garden, do consider the problem of soil erosion caused by poorly designed or high-crowned gardens. Avoid mounding soil unless it is contained. To prevent soil from washing into the street and affecting water quality, keep the final mulched surface of the garden an inch or so below the curb or sidewalk. An option is to add a front edging of block. Shredded hardwood mulch or the mulch of your choice will help control weeds, retain soil moisture and prevent erosion.

More horticultural information can be found on the University of Minnesota Extension website: Master Gardeners are also responding to your horticulture questions at (218) 444-7916; leave your name, number and question and you will receive a return call.