Prairie Management Procedures

First Year
Pulling Weeds
Second Year
Third Year and Beyond
Frequency of Mowing or Burning
Controlling Perenial Weeds
NEVER SPRAY

Post-Planning Weed Control - Very Important!

First Year

Perennial wildflowers and grasses grow slowly, and annual and biennial weeds will grow much faster in the first two years. Weeds can be controlled by keeping them mowed back to a height of 6 inches the first year. Most native wildflower and grass seedlings will not grow taller than 6 inches in their first growing season, and are seldom damaged by mowing. Keeping weeds cut back in the first year also prevents production of more weed seeds that could cause problems in the second year. Mowing weeds on a regular basis in the first year of establishment is one of the most critical steps in the success of your prairie planting. Do not fail to keep weeds in check!

A flail-type mower works best, as it chops up the weeds and prevents the clippings from smothering the small prairie seedlings. Rotary mowers and sickle bar mowers are OK, but they do not chop up the weeds, and can smother seedlings. String trimmers or Weed-Eaters are excellent for cutting back weeds on smaller plantings of an acre or less. These devices gently lay the cut material down on top of the cut stems where it will dry out rapidly.

Weeds should be cut back in the first year when they have reached a height of 12 inches. Do not allow the weeds to get taller than 12 inches before cutting. Tall weeds will shade out your seedlings, and the large quantities of weedy material that will have to be cut back can smother the small seedlings. Expect to mow weeds about once a month in the first year. The actual mowing frequency will depend upon rainfall in any given year, and the actual weed density and height.

If a nurse crop such as annual rye was planted with the prairie seed, it should also be cut back along with the weeds during the first growing season. This will not jeopardize the effectiveness of the nurse crop. Its purpose is to rapidly stabilize the soil, prevent erosion and provide cover for the newly-germinated prairie seedlings. Once weeds reach 12 inches tall and need to be mowed, the nurse crop will have done its job.

At the end of the first season, do not mow down the years growth. Leave it to help protect the young plants over the winter. The plant litter and the snow that it catches will insulate the soil, reducing the risk of plant losses due to frost heaving.

Pulling Weeds

Despite the temptation, pulling weeds in a first year prairie seeding is strongly discouraged. Wildflower seedlings remain very small the first year, and are easily pulled up along with the weeds! If you can identify weeds when they are young and only a few inches tall, it is safe to carefully pull them, making sure you do not disturb adjacent wildflower or prairie grass seedlings. If you must pull a large weed, hold your feet closely together on either side of the stem at ground level, and pull straight up. This will hold the surrounding soil and any nearby prairie seedlings in place as you extract the weed. Firm any disturbed soil and seedlings by tamping with your feet. If the soil is dry, watering after pulling weeds is beneficial for seedlings that may have been dislodged during the process. Beware that pulling weeds creates soil disturbance, which exposes new weed seeds and encourages their germination. If you have large, well-established weeds, cut them off at the base using pruning shears. Remove any seed-bearing weeds from the site immediately after cutting.

Second Year

In midspring of the second year, the planting should be mowed right down to the ground, and the cuttings raked off, if possible. At this stage, the prairie plants are still small and have not yet gained full control of the soil environment. Weeds will often be dominant again in the second season. Since many prairie seeds germinate over a two year period (or longer), burning in spring of the second year is not recommended, as it could kill new seedlings. Spring mowing exposes the soil and stimulates germination of dormant prairie seeds, as well as growth of the prairie plants that germinated in the first year.

If weeds are a problem in the second year, they will need to be mowed in late spring or early summer at a height of one foot. Biennial weeds, such as Burdock, Wild Parsnip, Bull Thistle, Curly Dock and Queen Annes Lace can be competitive in the second year. Mowing them to a height of one foot when they are in full bloom (usually early to late June) will kill them, or set them back severely. The prairie plants are seldom more than a foot tall in June of the second year, and will experience minimal damage, if any.

A biennial weed of concern is Sweet Clover (Melilotus spp.).This weed must be controlled because its seeds are stimulated to germinate by fire. In prairies that are managed with burning, this weed can become a long-term management problem if not handled early on. Mowing in midsummer of the second year when in full bloom will usually kill Sweet Clover plants and prevent them from making seed that will reinfest your prairie. If it reappears in the third year, it will likely be on a limited basis and can be hand-pulled. Do not let Sweet Clover make seeds, as it can be a most pernicious weed.

Third Year and Beyond

Burning and Mowing Management

Burning or mowing your prairie meadow on a regular basis helps ensure its continued success. Burning or mowing is usually, but not always, conducted in midspring. The best time to burn most prairies is generally when the buds of the Sugar Maple tree (Acer saccharum) are just opening in spring, or when you mow your lawn for the first time (April 1 to May 15, depending upon your location). A midspring prairie fire sets back undesirable “coolseason” weeds such as Quackgrass, Bluegrass, Brome Grass, Clover, etc., which come up earlier and get a head start on the prairie plants. By waiting until these undesirable plants have initiated spring growth before burning, the fire will destroy their new growth and set them back, favoring the warm season prairie plants, most of which remain dormant under the soil and thus unharmed by the fire.

Burning also removes the accumulated plant litter from the previous year’s growth and exposes the soil surface to the warming rays of the sun. Most prairie plants are “warm season” plants and respond favorably to warm soil temperatures. Burning encourages earlier soil warming and typically increases growth, flowering and seed production of the native flowers and grasses.

Timing is critical to success with burning. It is generally recommended to burn in midspring rather than early spring. However, this does not apply to dry prairies with an abundance of early-blooming wildflowers that would be harmed by a midspring fire. Dry prairies should be burned in late fall after most of the native plants have gone dormant, but the non-native cool season grasses are still active. Burning in very early spring can also be done successfully on dry prairies.

Spring Mowing as an Alternative to Burning

In the event that burning your prairie meadow is not an option, mowing can be substituted. Although not quite as effective as burning, mowing and raking off the cut material is a good substitute. Mow right down to the soil surface, or at least within one inch of the ground. Rake off all the cuttings to expose the soil to the sun. Mowing in midspring simulates the effect of fire by removing the previous year’s vegetation, and by cutting back cool season grasses and weeds that have already begun active growth. It is important to remove the mowed material to expose the soil surface and encourage soil warming. Do not mow or burn after new plant growth has reached one foot or taller, as this could damage your prairie plants. Many ground-nesting birds also build their nests in late spring and mowing or burning at this time could destroy some nests. Midspring burning or mowing maintenance leaves sufficient time for birds to renest and successfully raise their young.

Regular spring burning should be instituted at the beginning of the third growing season. Sufficient combustible plant matter is usually available from the previous year’s growth to carry a fire. If there is insufficient fuel to support a burn, mowing and raking should be substituted.

Frequency of Mowing or Burning

Most prairies and meadows respond positively to periodic burning or mowing. Research indicates that annual spring burning tends to favor the prairie grasses and legumes over most of the other flowers. A study conducted by Prairie Nursery showed that when one-half of the same prairie planting was burned in midspring and the other was left unburned, the appearance of the plantings were markedly different. In fall, the burned half was dominated by prairie grasses, while the unburned half exhibited fewer grasses, but more asters and goldenrods. The structure of the plantings in terms of the actual numbers of individual flowers and grasses was similar, but the flowering patterns were very different.

Rotational burning or mowing of one-half of your meadow every other year is recommended, for a variety of reasons. First, the burned or mowed portions will have a different appearance from the unburned or unmowed portions, increasing the landscape interest and diversity of habitat for wildlife. Second, leaving unburned sections preserves overwintering butterfly, moth and other invertebrate pupae and eggs, that would otherwise be destroyed by burning. Third, variation in management prevents any given species from gaining overall dominance in the planting, thus maximizing species diversity. Burning frequencies of every other year prevents the invasion of most woody plants into the prairie. Intervals of three years or longer between burns tend to allow the establishment of trees and shrubs in the prairie. This can result in increased maintenance in order to remove woody plants that become established in the prairie. If mowing management is to be used instead of burning, rotational mowing is recommended for these same reasons.

Controlling Perennial Weeds

Certain invasive perennial weeds may find their way into your prairie and become evident in the second or third year. Although burning and mowing will control most weedy species, a few perennial weeds may require spot treatment or removal. These include such thugs as Canada Thistle, Canada Goldenrod, Horsenettle and Spotted Knapweed. Canada Thistle and Horsenettle are tap-rooted weeds, and cannot be effectively pulled, as they re-sprout relentlessly. The only effective way to control these problem weeds is to hand-treat them with herbicides using “The Glove of Death. ”Wear rubber “herbicide gloves” and apply a large, absorbent cotton glove over one of the rubber gloves. Mix a strong solution of Roundup or other appropriate herbicide in a small spray bottle or other non-spill container. Carefully saturate the cotton glove with the herbicide solution, and grab the leaves and stem of the offending weed to apply the herbicide on that plant only. Do not touch other adjacent desirable plants, as they can be killed, too. Use this method only on cool, windless days. Herbicides volatilize on warm days, and the wind can blow the mist onto adjacent plants.

NEVER SPRAY HERBICIDES IN YOUR PRAIRIE!

The drift from the spray will kill desirable native plants in a wide swath, leaving large dead patches that will then grow up to weeds.

Non-tap-rooted weeds can be carefully pulled from a mature prairie. The roots of the prairie plants should be sufficiently developed to resist being pulled up with the weeds. Spotted Knapweed can be readily pulled. Rhizomatous Goldenrods, such as Canada Goldenrod, can be pulled when the soil is damp after a rain, but will require repeated pullings to remove them completely. Unwanted “bad” Goldenrods can also be killed using the “Glove of Death” method.

Once your prairie has become well-established, it will return year after year with just a minimum of maintenance. Following these guidelines will ensure that your planting will have the very best chance of success, while providing you with a maximum of landscape interest throughout the year!