It's true that wildflowers in the wild manage to grow without assistance from human gardeners. Gardeners trying to establish a wildflower meadow, however, will get better results if they pick a suitable site and prepare it properly. Sandra Richards, Master Gardener coordinator at Macomb County MSUE says most meadow wildflowers will grow best on a well-drained site with at least several inches of topsoil. On a dry site with no topsoil or a poorly drained clay, wildflowers will have just as much trouble growing as vegetables would, she says.
A key part of site preparation is eliminating perennial weeds such as quack grass, Richards advises. "It's a good idea to start preparing the site a year ahead," she suggests. "Repeated tilling will eventually remove competitive perennial grasses and other vegetation. It will also bring seeds of annual weeds to the surface where they can germinate. Then the next tilling kills them."
People often opt for a combination approach: an application of a broad-spectrum herbicide such as Roundup to get rid of the perennials and tilling to control germinating annuals. "However you choose to do it, eliminating quack grass and other perennials is a must if your wildflower planting is going to succeed," Richards says.
Another important step is selecting plants native to the Great Lakes states. They are best because they're adapted to local growing conditions. This is especially important in perennials, which must survive over the winter. Plants from more southerly parts of the United States may not. Easy-to-grow perennials for beginners include black-eyed Susan, coreopsis, gray coneflowers (on good soil, they will grow to a height of 6 feet), joe-pye weed, butterfly weed, purple coneflower, bergamot (a great butterfly plant), New England asters (purple) and goldenrod. Perennials can be slow to get established, and many don't bloom the first year. Most mixtures of wildflower seeds contain some annuals for quick cover and color the first year and perennials for the long haul, Richards observes. Some of the annuals may reseed themselves. Even if they don't, they'll take up space that first year that would otherwise be available for weeds.
Early spring -- as soon as the soil is dry enough to work without clumping -- is the best time to sow a mixture of annuals and perennials, Richards says. Perennials can also be seeded in the fall.
Before seeding, the soil should be worked lightly with a garden rake, lawn thatcher or rototiller. Distribute seed with a hand-cranked whirlwind seeder, if possible, and strive to spread the seed evenly.
A wildflower meadow tends to have clumps of species rather than a homogeneous mixture, so some gardeners will buy seed or transplants of specific varieties to plant together in clumps or drifts. Blending the edges of these colonies blurs their boundaries and adds to the natural look.
How much seed do you need? For a 750-square-foot area, 1 to 2½ ounces of perennial seed, ½ to 1 ounce of native grasses and ½ to 1 ounce of annual wildflower seed. Mixtures usually have filler material to make them easier to spread evenly, so labels will call for larger quantities for a given area, Richards notes.
After sowing, firm the soil bed with the back of a garden rake or, for a larger planting, with a lawn roller. Watering is not necessary, though it will speed germination and establishment. If you decide to start watering, it's a good idea to continue during dry weather throughout the first growing season, Richards suggests. The big chore during the first year is weed control. Weeds must generally be hand-pulled as soon as they're big enough to be distinguished from the flowers.
Once a wildflower meadow is established, annual maintenance consists of mowing to a height of 4 to 6 inches in late October or early spring, and burning the site every three years in March or early April.
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