- Selecting a Mix
- Site Selection
- When To Plant
- Use of Grasses
- Site of Preparation
- Seed Application
- Planting Rates
Selecting a Mix
Regional Mixtures are designed to fit the broad cross-section of conditions that generally exist within any one geographic region (and within any one project), i.e., variations in soil, slope, drainage, exposure and availability of moisture.
For example, we include species for both moist and dry conditions in each mixture, provided that these conditions exist in the particular region. Furthermore, species are included on the basis of their versatility or ability to adapt.
Sowing wildflower seeds without care and planning usually produces unsatisfactory results.
Here are some important factors to consider:
- Does the site support plants now? If you have a site where nothing—including weeds—is growing, that site is unlikely to support wildflowers.
- Will there be adequate moisture during germination and establishment? Can you supply supplemental water, if necessary?
- What weed seeds are likely to be present in the soil? Will weeds spread to your site from adjacent areas? Assessment of these factors will enable you to make a realistic choice of a site where wildflowers will prosper and to decide what action will be necessary to ensure your success.
When to Plant
The best time to plant in your area depends on the climate and rainfall patterns as well as the species you are planting. In cool climates, plant annuals, perennials or mixtures of annuals and perennials in spring, early summer or late fall. Fall plantings should be late enough so that seeds do not germinate until spring.
Perennials can also be sown in early fall provided that there are at least 10-12 weeks of growing time before the plants go dormant for the winter. Late fall plantings are advantageous when supplemental irrigation cannot be provided and adequate rainfall is anticipated in the spring.
In mild climates, plant during the cooler months of the year, fall through spring, for best results. Fall plantings done prior to periods of rainfall will insure an early display of flowers the following spring.
Use of Grasses
Wildflowers can be sown alone or with grasses. For specific requirements, individual species may be preferred. Warm-season grasses to consider include Sideoat Gramas, Little Bluestem and Blue Grama. These grasses grow very slowly and are planted for aesthetic and ecological reasons rather than prompt stabilization of soil.
Aggressive grasses should be avoided because they will crowd out most wildflowers; these grasses include Kentucky Bluegrass, Smooth Brome, and Annual Rye. If wildflowers must be used with these grasses, the flowers should be planted in high-density patches as accents to the grassed areas. Or the flowers may be sown with the grasses if the planting rates of the grasses are reduced significantly.
Site of Preparation
Proper site preparation is important for prompt germination of seed and healthy growth of seedlings. Best results will be obtained by planting on cleared ground. Remove existing vegetation to avoid competition from other plants. This may be done by pulling, tilling under, and spraying with a general herbicide, or by a combination of these methods, depending upon the size of the area, type and density of vegetation and other factors. Loosen soil by scraping, tilling or scarifying. Tilling should be utilized only when soil is very compacted and further weed control measures can be taken.
The method of application depends on the size of the area and the terrain. On small areas, broadcast seeds evenly either by hand or by use of a drop or cyclone spreader. It is helpful to mix a carrier such as clean, dry sand with the seed; sand adds volume and aids in even distribution.
We recommend using a ratio of 1 or 2 parts sand to 1 part seed. Rake in lightly, covering seeds to a maximum depth of 2-3 times their thickness. Or drag the area lightly with a piece of chain link fence to mix the seed into the surface of the soil. For seeding large areas, i.e., over one acre, specially designed drills are most effective. Drill to a maximum of ¼ inch and firm soil with a cultipacker; this maximizes seed/soil contact.
Hydroseeders are also effective, especially for steep slopes, rocky terrain and other areas where conditions make it impractical for driving equipment. Hydroseeding is the application of a slurry of seed and water to soil. The slurry may also contain mulch (hydromulching), a tackifier and fertilizer.
Mulches are made of wood fiber, paper or excelsior, and their purpose is to hold seeds in place, help retain moisture and provide protection from erosion; mulches are usually dyed green as a visual aid in even distribution. Rates of application for most mulches are between 1500 and 2300 pounds per acre. In general, hydroseeding/hydromulching is most successful in moist climates or in irrigated areas.
Most authorities agree that germination is better when seed is applied first with 5-10% of the mulching fiber—the balance of the mulch being applied separately as a second step. This approach ensures optimal seed/soil contact; otherwise, many seeds are wasted because they become suspended in the fiber.
It is important that proper procedures are followed to minimize the amount of time that seed is circulated through pumps or paddles prior to application. Over-circulation may damage the seed.
All seeds, including wildflowers, need ample moisture to germinate and to develop into healthy seedlings. Best results will be obtained by soaking the planted areas thoroughly and maintaining consistent moisture for 4-6 weeks — then gradually reducing waterings. In non-irrigated situations, plant in the spring or before periods of anticipated rainfall.
After seedlings are established, watering may be reduced depending on the climate and rainfall. In arid climates or during drought conditions,up to 1/2 inch of supplemental water per week may be required to maintain an optimal display. If weeds are present, remember that they benefit from moisture as much as the wildflowers and may dominate over watered areas.
Many wildflowers benefit from some fertilization if the soil does not have adequate nutrients. Some wildflowers do fine in poor soils, while others require a more fertile environment. We recommend that a soil test be performed when soil quality is unknown.
If the soil needs improvement, use a low nitrogen fertilizer with a 5-10-10 ratio or add organic matter such as weed-free straw or grass clippings, well-rotted compost, peat moss, or leaf mold. In addition to adding nutrients, organic materials enhance soil structure and encourage beneficial microorganisms.
Avoid over-fertilizing which may promote weed growth and lush foliage rather than flowers.
In general, the minimum planting rates are based on 60-70 seeds per square foot (4 to 12 pounds per acre), which is usually sufficient to establish a good stand of wildflowers on prepared soil when adequate weed control can be maintained.
Maximum planting rates are based on 120-140 seeds per square foot (8 to 24 pounds per acre), and are recommended when adequate soil preparation and weed control are not possible, or when maximum color is required. Avoid using more than the recommended rates since poor perennial establishment may result.