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Site Preparation

A field two weeks after spraying with herbicide. A single spraying seldom kills all the perennial weeds. Please refer to the text for other non-herbicide soil preparation methods

Lightly till the seedbed after all weeds have been eradicated

Levelling the seedbed creates a smooth even surface for the seed

 Proper soil preparation is the single most important factor in the success of any wildflower planting. The seed bed must be smooth and weed free. Existing weeds will compete with prairie seedlings for nutrients, water and sunlight. If not controlled they can considerably delay the growth and maturation of your meadow. A smooth, clump-free seed bed will guarantee firm contact between the soil and seed, enhancing seed germination. Whether you're planting seeds or transplanting plants adhere to the following guidelines to ensure good results.

The first step in soil preparation is to remove the existing vegetation. You can do this by smothering, cultivating, herbiciding, or employing a combination of these techniques.


On small areas of a few thousand square feet or less, smothering weeds on the area is simple, effective, and requires no chemicals or special equipment. Smothering involves covering the soil surface with black plastic, old rugs, 4x8 pieces of old plywood, or a thick layer of leaves. This should be left in place for a full growing season in order to kill the plants underneath.

If you choose to use herbicides, we recommend using a broad spectrum, non-persistent herbicide. The best organic choice is to use a vinegar based herbicide such as Elima-Weed. Please note vinegar based herbicides will require at least three applications over a growing season to be fully effective. Alternatively, there is the non-organic glyphosate based herbicide (ie. Roundup). PLEASE NOTE: NON-ORGANIC HERBICIDES ARE NOW ILLEGAL IN ALBERTA, ONTARIO AND QUEBEC. When using herbicides, READ THE LABEL, and follow the manufacturer's instructions or hire a professional.

If you prefer not to use herbicides at all, a variety of equipment is available to prepare your soil using cultivation only. A sod-cutter, rototiller, tractor-mounted rototiller, rotovator, or farm implements such as a plow, disk or harrow may be used, depending on the size of the area to be planted.

Lawns The quickest way to prepare a lawn for planting is to remove the top three inches of grass and soil using a sod-cutter. This usually creates a nearly weed-free planting site ready for seeding or installation of transplants. Be aware that the area will be lower than the surrounding lawn after sod removal. Sod cutters can be rented for this procedure.

When using herbicides, apply in fall or spring, when lawn grasses are actively growing. Cultivate after everything has turned brown to prepare the seedbed for planting (about two weeks after spraying).

To remove an existing lawn by cultivation, you will need to cultivate 2 to 3 times, approximately 1 week apart. If rhizomatous perennial grasses such as Quackgrass or Johnsongrass are present, a year-long tilling program may be required to eliminate them.

Old Fields are difficult to work up due to the presence of a variety of perennial weeds. An old field usually requires at least one full growing season to prepare the site. This may seem long, but a little patience at this stage is essential for a successful planting.

To herbicide, begin by mowing in early spring to remove the previous years growth. This will encourage new spring growth. Apply either an organic vinegar based herbicide such as Elima-Weed or a non-organic glyphosate herbicide three times throughout the season, once in mid-spring, again in mid-summer, and finally in early fall, unless no plant growth is visible one month after the second spraying. This schedule allows you to attack different weeds which have peak activities at different times. When the existing vegetation is clearly all dead, prepare the seedbed for planting.

Using cultivation only you will need to cultivate beginning in spring and continuing through fall. Cultivate every two or three weeks at a depth of 4-5 inches. Be religious about this. If you are fighting rhizomatous, perennial weeds, waiting longer than 2 or 3 weeks will allow these weeds to recover. For some species, such as Quackgrass, cultivating in intervals greater than 2 weeks may actually increase its density.

Corn, Soybean, and Small Grain Fields typically have less weed problems compared to old fields, and require less preparation. Corn, bean, and grain fields can usually be sprayed with herbicides once, or twice if necessary. Spray in mid-spring for a spring planting, or after crop removal for a fall planting. If perennial weeds are common, site preparation will require a full year, similar to old fields.

The seedbed may be prepared without herbicides, using cultivation as you would for any other crop. If rhizomatous perennials are present, work up the soil all year, as described for old fields. Once all existing vegetation is removed, the final seedbed should be prepared by tilling or discing, followed by dragging or raking.

Do NOT plant wildflowers in fields treated with Atrazine within the last 2 years. While some native grasses can tolerate low levels of Atrazine, wildflowers cannot tolerate any. Atrazine breaks down in 2 to 3 years depending upon soil type, precipitation, and the amount originally applied. A smother crop of corn or sorghum will hold your soil for a year and control unwanted weeds while the Atrazine breaks down.


Erosion Prone Sites Precautions need to be taken on erosion prone sites. To avoid runoff and soil loss the site should not be left unvegetated for any length of time. Cultivation should be kept to a minimum. Preparing your site solely by cultivation may create unwanted erosion problems. The site should be planted immediately following soil preparation. Use a nurse crop of oats and a covering of mulch, stabilized with netting to hold the soil.

If you are unable to plant your seed immediately the site may be stabilized by planting annual rye at a rate of 50 lbs. per acre.. Till the rye under when ready for planting or spray with a herbicide and no-till plant into the dead stubble.


A Final Pre-Planting Tip After the existing perennial vegetation is eliminated, weed seeds still lurk in the soil below. These seeds will germinate and compete aggressively with your wildflowers and native grasses. Weed density can be greatly reduced by a final herbicide treatment of the surface just prior to planting in late spring or early summer (this treatment will not work in late summer or autumn).

Start with a prepared seedbed. Allow weeds to germinate and grow. Apply herbicide when the weeds are 2-3 inches tall. Wait 10 days, and then shallow till the soil one inch deep. Tilling deeper will bring up more weed seeds to the surface. Plant immediately.

If you prefer to avoid using herbicides, similar results can be obtained using well-timed, careful cultivation. Start with a prepared seedbed. Till the soil one inch deep 5 to 7 days after the first good rain. This will kill weeds after they germinate but before they come up, without bringing up more weed seeds. On sandy soils, a drag can be used. A very light discing is usually more effective on heavy soils. Plant immediately.

This final treatment can greatly reduce weed competition, yielding faster growth of wildflowers and prairie grasses. A well prepared site is half the battle when establishing a wildflower meadow. By removing the existing vegetation, and providing a suitable seed bed for germination and seedling growth, you are well on your way to a successful planting. Once established, your wildflower meadow will bring you years of enjoyment with a minimum of maintenance!

 

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