You may be one of many individuals who has attempted to grow wildflowers by sowing a seed mix, only to experience failure by the third year if not sooner. Successful seedings of wildflowers depend on the right mix of native species for the area, soil preparation which primarily involves killing any exotic vegetation present, timing of the seeding, and weed suppression after the seeding. From the third year on an annual or biennial mowing or burning will keep the flowers blooming and trees and shrubs from invading.

When planting on deep, tillable soil sites (good or poor soil), a successful seeding of wildflowers and native grasses depends on having a seed bed with no living vegetation at both the time of seeding and when the seeds germinate in the spring.

Because many native wildflower species have a high percent of dormant seeds that require a cold-moist period before germination, the most successful wildflower plantings are done in late November, December, or early January. That also insures the seeds will be in the soil in the spring when conditions are right for germination. Native grasses can be seeded from January to May. May is ideal for seeding grasses alone or when putting them in a large wildflower seeding with a no-till drill.

The easiest sites to seed with wildflowers are those with very dry, shallow soil where bed rock is six inches or less from the surface. These sites are frequently too dry to support trees or exotic cool season grasses like fescue. Use species adapted to sunny, dry conditions. Just scattering the seeds on the surface during late fall and early winter may be all that is necessary for these sites. Due to dry conditions it may take an extra year or two for the wildflowers to start blooming. Dry sites can go much longer without needing a fire or mowing disturbance.

It is better to plant the seeds of species that are adapted to the existing site than to add soil for a desired mix of species. When picking a mix of flowers, use a deep soil seed mix for deep, clay soil that is flat to gently sloping in sun, even though it seems dry. A dry soil seed mix (or dry soil and deep soil mix together) could be used on a steep south or west facing clay slope.

Getting Started
1. Evaluate the site and plan the timing of activities; determine the kind of soil, its pH, what and when to plant, and when and how to kill the non-natives.

2. Kill the existing non-native vegetation. Most non-native cool season grasses, like fescue, can successfully be killed. Don't plant wildflowers on areas where sericea lespedeza, bird's-foot trefoil, or crown vetch have seeded because the hard seeds of these exotic legumes may lie in the soil for ten to twenty years before germinating.

¥ One way to kill the existing vegetation is to cover the area with black plastic during fall or spring for about two months. Plants under the plastic that are not actively growing may not be killed by this process. Warm season lawn grasses need to be covered during the summer when they are actively growing. Keep the area covered until you are ready to plant. The vegetation should be dead not just yellow.

¥ If killing the vegetation with herbicides, be sure to follow label instructions. Glyphosate, the active ingredient in RoundupTM herbicide, can be used on actively growing plants with good results. Try to have at least 4-6 inches of growth on a lawn before spraying. A fescue field with a lot of dead, old growth might need to be hayed or burned in July or August to encourage active new growth for a fall spraying. Watering the site might be necessary in early September to encourage active growth during a dry period.

¥ At least two herbicide applications are usually required to achieve a total kill of the vegetation. If weeds germinate in the fall after the ÒlastÓ application, another application will be needed in late October or early November on a warm sunny day. These winter annuals (weeds that germinate in the fall and bloom the following spring) can bring disaster to your project. As a last resort, they can be killed before the end of February with glyphosate herbicide without harming the wildflower seeds.

3. If there is a layer of thatch (dead vegetation) covering 100% of the soil that would prevent seeds from making soil contact, the area should be burned or mowed and raked to remove the thatch, or drug with a harrow or a piece of chain link fence just before seeding to loosen and fluff up the thatch. This step is not necessary if the thatch covers about 80% of the soil or less.

4. Wildflowers grow best in soil between pH 5.5 and 7.5. If above or below these figures, the plants might not be able to take in nutrients from the soil. Fertilizer is usually not needed when seeding wildflowers. Nitrogen tends to encourage weed competition and it can hamper the growth of native grasses.

5. Sow the seeds on the surface in late November through mid January and let freezing and thawing work them into the soil. The seeds will germinate in the warm days of March and April. Warm season grasses won't germinate until the soil temperature is 60 degrees F (May). Even distribution of the seeds is important. Drills are good for large areas. Broadcast (cyclone) seeders will handle a flower mix but not grass. Hand broadcasting the seeds works well for small areas up to an acre or so, however be sure to dilute the seeds with a small particle, light substance like sawdust, peat, or vermiculite to achieve even distribution of the seeds.

Maintaining the Project
1. During the first growing season cut the weeds (and wildflowers) back to six inches high when the average weed height is one foot. Most perennial wildflowers and native grasses remain less than six inches high their first year.

2. During the second growing season cut the weeds only if they are thick and creating a closed canopy above the ground. Again, cut the weeds (and wildflowers) back to six inches high when the average weed height is one foot.

3. From the third year on, an annual mowing or burning of all or part of the planting will promote the vigor of the fire-dependent wildflowers and grasses and help prevent the invasion of many fire intolerant trees, shrubs, and exotic species. This mowing or burning can be done any time except mid March through mid July when the wildflowers are actively growing.

4. Always remove or kill any of the exotic legumes ASAP.