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Fielding Questions: Corn gluten meal can prevent crabgrass

Don Kinzler, gardening columnist 1 / 2
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Q: I purchased a product called Maize Weed Preventer at a local nursery to apply in hopes of preventing annual crabgrass seeds from sprouting in the lawn. Does this product work? When is the right time to apply?—Sandy Gjervold, Fargo.

A: The product contains corn gluten meal, which was discovered to kill seeds as they germinated, making it a good pre-emergent weed product, especially for people who prefer an organic weed preventer. It's been widely researched by Iowa State University and found to be effective.

Crabgrass can be prevented in lawns by applying such pre-emergent products. Crabgrass seed begins germinating when soil temperature 1 inch below surface reaches 57 to 60 degrees, so products must be applied before that time. Weather services provide soil temperatures, and although it varies by the year, crabgrass preventer is usually best applied by late April.

Q: Our back yard is 50 percent clump fescue. How can we eliminate it entirely?—Jean Johnson, Moorhead.

A: The coarse, wide bladed, dark green grass that is frequently seen growing in clumps in area lawns is usually the grass called tall fescue. Lawn seed mixtures sometimes contain tall fescue, either intentionally, or as a contaminant. Although varieties of tall fescue have been developed for whole-lawn use, when it's in combination with Kentucky bluegrass, it appears as weedy clumps.

There are no products that will selectively remove tall fescue from lawns without also damaging desirable grass. Spot-spray fescue clumps with non-selective herbicides like Roundup and then reseed. If clumps aren't widespread, they can be removed by digging.

Q: This winter wet, heavy snow fell off the roof onto the globe arborvitae by the house, breaking some of the center branches. Should the branches be pruned off? Do you think they'll fill in again to be nice round plants as before?—Kathy Alveshere, Harvey, N.D.

A: If the central branches are cracked or snapped, they should be cut off below the break. If the branches are just bent down but not broken, branches can be tied back upright. If looping a soft material around the shrub and pulling taut doesn't pull branches into their original shape, drive a stake in the middle of the shrub and pull the bending branches back upright and secure with cloth or similar soft strips. The wooden stake can be low enough in the shrub's center so it's less visible.

If branches are snapped and broken, pruning can be done now. Evergreens don't sprout well from low, interior wood, so whether there are enough healthy branches to allow recovery will be a judgement call, or whether replacement is the best option.

Q: I want to broadcast 10-10-10 fertilizer across my perennials beds this spring. When is the best time to do this? I have lots of lilies, daylilies, grasses and other standard perennials.—Lori Keller, Barney, N.D.

A: Fertilize perennials anytime in spring as growth begins, or just before. Granular types can be cultivated shallowly into soil an inch or 2. Fertilizer can be broadcast throughout the perennial bed, or placed in circles around individual plants. Fertilizing of perennials should stop around July 4, to prevent stimulation of late summer growth that won't have sufficient time to toughen up before winter.

If you have a gardening or lawn care question, email Don Kinzler at All questions will be answered, and those with broad appeal may be published, so please include your name, city and state for appropriate advice.