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Wildflower Planting Guidelines
Expectations and Steps for Success
Perhaps the most appealing thing about wildflowers is their combination of beauty and self-sufficiency. They offer a dazzling range of color and form while displaying hardiness and adaptability not usually found in their more domesticated cousins, the garden flowers. These qualities make them ideal for landscaping applications where a low-maintenance approach is desired like: parks, industrial buildings, roadsides, country clubs, “roughs” in between golf course greens, landfills, re-vegetation projects, and of course home owner landscapes.
While a natural display of wildflowers in a meadow may look to be a casual phenomenon, natural forces may have taken years to achieve such effects. Wildflower plantings offer a beautiful, low-cost alternative for large area landscaping, but require the same careful planning and preparation as any traditional landscaping projects. The following guidelines for site preparation and planting wildflowers should be followed for maximum success.
The first steps of planning are to evaluate your site and decide how long you wish your planting to persist.
1. Site evaluation: Look over your potential site(s).
What is growing there now? If not even weeds are present, chances are your soil won’t support a wildflower planting without extensive preparation and the addition of some amendments.
Is there an excessive weed population? Has the site been uncultivated or untended for years? In these cases, extra steps will be necessary to rid the site of existing weeds and dormant weed seeds in the topsoil that will compete with your wildflower planting for light, moisture and nutrients.
How much moisture naturally occurs on your site and when? It is vital that your planting receives sufficient water (via natural rainfall or supplemental irrigation) in the first 4-6 weeks to germinate the wild flower seed you plant. Water can gradually be reduced as the planting matures. In areas where the summers are warm and relatively dry, up to 1/2 inch of supplemental water per week may be required to allow your planting to develop to its maximum potential.
How much sunlight does your site have? At least 8 hours of direct sunlight are required unless you are planting a partial shade mix or are planting shade-tolerant species.
Is your site relatively level, or is it sloped or subject to water erosion? Sloped sites require extra steps after seeding to insure that the seed remains in place and is allowed to germinate and establish.
Longevity of the planting:
If your planting is only required for one season, consider the dazzling color and variety provided by an all-annual wildflower planting. You may also choose to re-create this effect every year by over seeding with you chosen mix or simply replanting your site with our all annual/over seeding wild flower mix.
If you wish your wild flower planting to persist for at least a second season, you will want a mixture that contains annuals and first-year flowering perennials for the first season and biennials and 2nd year flowering perennial wildflowers for the second year.
To maintain your planting beyond 2 years, we recommend using one of our Native Regional wildflower mixtures, supplemented with cool season and/or native grasses. The addition of the grasses will help crowd out weeds in the second and subsequent years, which will increase the longevity of your wildflower planting.
Proper site preparation and ongoing maintenance of your planting is vital to the success of all wildflower planting, whether the desired life of the planting is one, two, three years or more.
What to Plant
We generally recommend planting a mixture of wildflower species that are adapted to a single geographical region. Our regional mixes generally contain 15-20 species with a 50/50 ratio of annuals to biennials/perennials. Since few wildflower species will bloom over a whole season, our formulations contain spring, summer, and fall blooming wild flower species. We also include some species which are suited to dry conditions and some which are suited for moist conditions; some for light soils and some for heavier soils.
Grasses can be added to wildflower plantings to give a more meadow-like appearance and to suppress weed growth. We recommend hard fescue/sheep fescue and warm season native grasses for Northern, Midwestern, and Western states. In Southern states, we recommend just warm season native grasses. We do not recommend using pasture grasses such as bluegrass, brome, crested wheatgrass, annual ryegrass or orchardgrass because they are too aggressive and will suppress wildflower growth.
Planting rates for wildflowers are based on 75 seeds per square foot, which is optimal for relatively flat sites with average weed population. For difficult sites, i.e. slopes where erosion is a problem, soils with high weed pressure, or sites or which adequate weed control can not be maintained. we recommend doubling these rates for wildflower planting. When fine fescue grasses are included in a mixture, they should be planted at a rate of 10 lbs per acre. The wildflower mixture should be planted at the recommended rate or even increased by 25%.
When to Plant
In climates with a freezing winter, wildflowers can be planted in the spring after the danger of frost has passed. The latest spring planting date would be approximately mid to late June, depending on the date of the first frost. Wildflowers can also be planted in the Fall, as long as soil temperatures are cool enough to prevent early germination (generally this would be mid-October). Perennial and biennial wild flowers can be planted in mid to late summer as long as there is sufficient time for the wild flowers to become established prior to the onset of winter (generally 10-12 weeks). In mild climates, plant wildflowers during the cooler months, generally October through March. Early to mid-summer plantings can be made if supplemental irrigation is available to ensure wild flower germination and growth.
Site Preparation Steps
1. Determine your soil type. Each soil type will require preparation, but sandy and clay soils may require additional care and steps.
Sandy soils dries out quickly, may be low in nutrients and have a low pH. Be prepared to add supplemental water to germinate your wildflower seed unless you are in the rainy season. Adding additional organic matter, such as composted yard wastes, will increase the soil’s water holding capacity as well as available nutrients for you wild flowers. If you do not choose to add organic matter, a soil test will help you determine whether adding a low-nitrogen fertilizer and lime will be necessary.
Loamy soil contains more organic matter than both sandy soil or clay soil and therefore retain adequate moisture while providing necessary drainage. These soils are the easiest to prepare for wildflower seeding and provide an excellent wild flower site.
Clay soil is heavier than sandy or loamy soils. It retains water easily, but does not allow proper drainage for most wildflowers. If it dries out during a hot summer, it becomes hard and prevents wild flower roots from penetrating deeply into the soil. Clay soils generally contain sufficient nutrients, but benefit from added organic matter to increase drainage. Another method of adding organic matter to the soil to improve wildflower plantings is to plant a green manure crop such as buckwheat or winter wheat. Plow this crop under while actively growing to incorporate the roots, stems and leaves into the soil. As they break down they will enrich the soil and add organic matter to help your wildflowers grow.
2. Remove existing vegetation. Reducing competition for space, light, moisture and soil nutrients is essential to the success of your wildflowers. This can be done by smothering, mechanical removal or by using herbicides.
Smothering: vegetation on small areas can be effectively killed, along with dormant seeds in the top several inches of soil, by covering the area with black plastic. The increased soil temperature will kill weed seeds, while the lack of sunlight and moisture will kill existing vegetation. For the full effect, leave the plastic in place for a full growing season.
Cultivation: using this technique alone will require repeated passes, at 2-3 week intervals, preferable with supplemental water, over a full season to be effective. This is because tilling will bring to the surface more dormant weed seeds which will interfere with your wild flower planting.
Herbicides: using herbicides such as Round-up will usually require two applications, 3-4 weeks apart to kill the existing vegetation. After the first application, wait for the weeds to die back then remove them by cutting, weed whipping and raking. You may want to shallow till the ground before you plant your wildflowers.
Because wildflower seed mixtures contain seeds of vastly different sizes, blending an inert carrier like fine sand or vermiculite with the seed will help to insure an even distribution (4:1 sand to seed is recommended). For small areas, hand broadcasting the wild flower seed along with an inert carrier will work quite well.
For larger areas, mechanical seeding such as a cyclone-type seeder, a brillion seeder or a no-till seed drill work well, but tests must be made in order to achieve the proper planting rate of the wildlfower seed with each type of machine.
Once the seed has been planted, it must be covered to a maximum depth of 1/8 to 1/4 of an inch. This can be achieved by lightly raking the seed in with a hand rake for small areas, or by using a drag mat behind a tractor for larger areas. If a drill seeder is used, firm the soil after drilling with a cultipacker to insure proper seed/soil contact. Care must be taken not to cover the wildflower seed too deeply as this is one of the primary reasons wild flower plantings fail.
Weeds left uncontrolled will quickly take over any wildflower planting. Removal of weeds during the initial site preparation must be followed. Once germination of the wildflower species has begun, newly appearing weed should be removed. Over seeding wildflowers with the originally planted mix or an all-annuals mix in the fall or early spring will help to fill in the bare spots and keep weeds down. The newly seeded wildflowers will increase wildflower density to crowd weeds out.
Post Planting Care
The planting must be kept moist 4-6 weeks, using supplemental water if necessary in order to ensure germination of as many wildflower species as possible. As the planting becomes established, water can be gradually reduced from the wild flowers. Many wildflowers are drought tolerant once established, but must receive adequate water in order to germinate and to become established. You should begin to see wildflower seedlings within 2 weeks and the first flowers in 6-8 weeks. As the season progresses, several waves of color will be seen according to the blooming time of the wild flower species. In dry climates or in drought condition, 1/2 inch of water per week will lengthen the blooming period of the wildflower display.
Once the wildflower planting has stopper flowering and set seed, it can be mowed to a height of 4-6 inches. In most climates, this will be in mid-October. Mowing will help scatter the seeds for the next year’s wildflower blooming. After fall mowing or early the following spring, consider supplementing the site with some new wildflower seed in order to more firmly establish the permanence of the planting and to suppress weed growth.