Creating or Recreating a Prairie
By Charles M. Allen
The following “How To” for the development of prairies is mainly written for the coastal prairies of Louisiana and Texas but is applicable elsewhere especially in the southeastern United States. Thanks to the many people who have added to my knowledge of prairies especially Malcolm Vidrine, Peter Loos, and Marc Pastorek.
Prairies are usually defined as areas dominated by herbaceous perennials, in particular grass species and few woody plants, especially trees. Both woody plants and herbaceous perennials live for more than two years but the above ground stems of woody plants do not die back to the ground during the Winter so the above ground growth of stems for woody plants is cumulative. The above ground stems of herbaceous perennials die back to the ground yearly so new above ground stem growth begins fresh every Spring. The underground growth of herbaceous perennials is cumulative as this material accumulates from year to year. Other terms that have applied to prairies are meadow, field, plain, clearing, pasture, steppe, and alp. Artificial prairies have been created by humans throughout the world. Pastures, golf courses, parks, lawns, graveyards, railroad right of ways, and roadside right of ways are dominated by herbaceous perennials and are treeless or have areas that are treeless. Many areas that were cleared for agriculture and now abandoned often are allowed to develop into prairies or meadows.
Prairies are (or in some cases we have to replace “are” with “were” as the prairies are now destroyed) formed in many parts of the world under several environmental conditions. Prairies are created by elements that restrict the growth of trees and other woody plants and allow the growth of herbaceous perennials. Factors reported to restrict woody plants and thus promote prairie creation are:
(1) low annual rainfall—the prairies of the Midwest United States are reported to be mainly created by total annual rainfall of less than 30 inches;
(2) fire—this would kill the woody plants but not harm the perennials with their underground rhizomes and other survival parts;
(3) clay layer below surface of soil—a hard clay pan located below the surface restricts the growth of roots (the underground system of herbaceous perennials could develop above the clay layer but there would not be enough room for the root system of trees);
(4) high clay content of soils—soils with much clay shrink and swell with dry and wet conditions creating a hostile environment that herbaceous perennials can tolerate but trees cannot;
(5) wet/drought conditions—the inhospitable conditions created by wet conditions followed by extreme drought can be tolerated by herbaceous perennials but by many woody plants;
(6) grazing animals—bison and other herbivores can seriously damage woody plants by their concentrated grazing (herbaceous plants are grazed as well but resprout much more prolifically than woody plants);
(7) wind—woody plants are often blown over by winds while the herbaceous perennials are shorter and more flexible; and
(8) mycorrhizae—these are fungus-root mutual relationships where the fungus provides water and nutrients to the roots and receives food back from the roots (mycorrhizae are important for trees and the fungus may not be present in prairie areas).
Prairies do not develop as a result of one of these factors but a combination of two or more. Fire is the one that seems to be prevalent in almost all natural prairie systems.
The big keys to prairie creation or recreation are patience and perennials. Remember that herbaceous perennials grow above ground stems yearly, die back to the ground during the Winter, and regrow the following Spring. So many people are familiar with trees and forests and treat herbaceous perennials and prairies in a similar manner. A common mistake is to think that when the above ground stems die the entire plant is dead. But, perennials survive underground and will resprout next Spring if you don’t till the area or remove the sod.
- Light—a full sun setting is optimal but partial shade can be tolerated by many prairie plants. A densely shaded area will not work.
- Moisture—prairie plants can tolerate a wide range of moisture as there were wet and dry prairies. The best would be the intermediate moisture as too wet would have a tendency to develop into a marsh or bog and too dry may become a desert setting.
- Soil—prairies can be created on just about any soil but more fertile soils tend to create problems with weed control and woody plant development.
- Topography—the ideal setting is flat but prairies can be created on slopes unless the slope is very extreme and erosion problems may not allow prairie development.
- Size—prairies can be any size and the availability of the proper combination of the above four factors may dictate the size. Another factor to consider in size is the maintenance which will be covered later. If your prairie is too large to maintain, it will soon develop into a forest in most situations. The “postage stamp” prairie is a good one for the backyard in a residential situation. The front yard would also be okay but the prairie does look “weedy” or “ratty” at times of the year if you do no weed pulling. A front yard prairie is manageable with weed and height control and understanding neighbors.
- Prior vegetation—it is best to recreate a prairie in a site where prairie once grew but new or artificial prairies can be created just about anywhere where the above site conditions are met.
All woody plants should be removed from the site and this can be accomplished mechanically or with chemicals. If possible, herbaceous plants, especially the invasive species, should also be removed. The better the site preparation, the sooner you will have a prairie. If using seeds, you have to till the site as though you were planting an agricultural crop. The better the seedbed the more seeds will germinate. Do not be concerned about annual weed seeds, some seeds will germinate the first year but very few will germinate the second and third, etc. years as long as you don’t redisturb the soil. If using transplants (plugs and seedlings) to start the prairie, you do not have to prepare the area as intensely as with seeds but you will get faster results if you do.
Making the Plant List for the Prairie
Consult with a recognized expert (see http//www.cajunprairie.org) in your area to obtain a list of plants for your prairie(for a list of Cajun Prairie species, get Dr. Vidrine’s new prairie book). A few miles can make a big difference in the choices of plants that occur (or did occur) in your area and thus should be included in your prairie. Avoid already prepared seed mixes as these are usually for a wide geographic region. It is much better to make your own list so you can more accurately recreate the prairie of your area and also be able to include your favorites, especially with small prairies. For limited budgets, space, and/or local ordinances, be sure to take into consideration the characteristics of each species; height, flower color, and time of year of flowering. Some species can tolerate a range of the environmental factors while others have a very narrow range so light tolerance, soil, and water requirements should also be considered when choosing species.
Grasses usually formed the backbone or matrix of a prairie so it is important to include a number of grasses. If you are attempting to mimic the Cajun Prairie, you would need switch grass (Panicum virgatum), big blue stem (Andropogon gerardii), little blue stem (Schizachyrium scoparium), slender blue stem (Schizachyrium tenerum), Indian grass (Sorghastrum nutans), and eastern gama grass (Tripsacum dactyloides). These species are dominants in the remaining Cajun Prairie remnants. Other grasses that would be also important in the prairie are Florida Paspalum (Paspalum floridanum), brownseed paspalum (Paspalum plicatulum), muhly grass (Muhlenbergia capillaris), pineywoods dropseed (Sporobolus junceus), and several species of rosettegrass (Dicanthelium spp.).
A prairie would be very drab with grasses only so plants that produce colorful flowers should also be included in your mix. Some species or genera that would be essential are blazing stars (Liatris spp.), compass plant (Silphium laciniatum), rosin weed (Silphium gracile), flowering spurge (Euphorbia corollata), button snakeroot (Eryngium yuccifolium), false indigos (Baptisia spp.), Indian plaintain (Arnoglossum ovatum), grass leaved golden aster (Pityopsis graminifolia), snout pea (Tephrosia onobrychoides), phlox (Phlox pilosa), wine cup (Callirhoe papaver), sweet golden rod (Solidago odora), aster (Aster spp.), milkweeds (Asclepias spp.), tick seeds (Coreopsis spp.), wooly sunflower (Helianthus mollis), and Indian blanket (Gaillardia aestivalis).
Sources of Seeds and Transplants
Whenever possible, the seeds and/or transplants should be obtained from local sources. There are two reasons for this: (1) local plants are adapted to the local environmental conditions and (2) efforts should be made to preserve the local genetic strains and possibly prevent their extinction. It is reported that as little as 100 miles north or south canaffect the time when a species begins flowering and other steps in the life cycle of a plant maybe controlled by local environmental conditions. Many prairies exist as only small remnant populations so it would behoof us to try to get those genetic strains into as many protected places as possible and not allow these genetic strains to disappear.
Seeds may be purchased from commercial producers. When purchasing seeds, use the closest seed company to you and be sure to match the species exactly and don’t just plant any species in a genus. In some genera, there are some annual and some perennial species; Gaillardia pulchella is an annual while Gaillardia aestivalis is a perennial and a prairie plant. A listing of seed companies that offer prairie seeds is in Appendix B. Due to the constant flux in seed companies and the seeds that each offers, it may be necessary for you to contact the prairie organizations listed in Appendix C for more up to date data on prairie seed companies.
Seeds may also be harvested from the wild; it should be noted that the percent of germination of many wild collected seeds is often low. The gathering of seeds from perennials usually does not affect the number of plants in the area the following year because perennials regrow from underground parts. Seeds of perennials only germinate when a disturbance creates bare soil and an opening for the newly germinated seedling. Be sure to obtain permission before harvesting seeds. Seeds should be harvested as soon as possible after maturity; most seeds change from green to another color, brown, black, red, yellow, etc., with maturity. Place the seeds in brown paper bags and allow them to dry. After drying, you may place in plastic bags but be sure to not use a plastic bag for storage until the seeds are dry. If it is time for planting, you can plant the dry seeds as is. If you are not planting right away, it is best to store the seeds in a refrigerator until time for planting. The cool storage does apply some stratification (exposure of seeds to cold temperatures to cause the embryo to mature) and also protects the seeds from insect attack. If you are hand planting, you do not have to put a lot of effort into sorting the seeds from the chaff. If you plan to use a drill or other mechanical planter, you should separate the seeds from the chaff as much as possible.
Some companies offer potted transplants for sale. A good source for transplants is the state or local Native Plant Society. As with seeds, obtain you transplant from as near as possible. Note that some local companies may be buying their plants from other areas or even other states and then growing them to the saleable size. Check into the ultimate source of the plants before purchasing. It is not recommended that you dig transplants from the wild except for rescue missions. Rescue missions should be undertaken when the plants of an area are being destroyed for construction of highways, houses, parking lots, agriculture, etc. When rescuing plants, be sure to obtain plenty of soil with the transplants, protect the transplants from wind during transport, and schedule the rescue mission during the dormant season in your area, mostly January and February. Clumps or clods of soil plus the underground parts of plants should be inside a plastic bag if you have to transport for a long distance. Many clods may be placed in the back of pickups or trailers. If traveling for a long distance, the clods should be covered to prevent drying out by the wind. For seed, see http://www.cajunprairie.org/index.php or http://www.meadowmakers.com/
Seeding or Transplanting
The best time for seeding of prairie plants is late Fall to early Winter as would happen in nature. The plants in a prairie are staggered in flowering and seed production; there are some flowering in the Spring, some in the Summer, and many in the Fall. The seeds mature at different times but most reach the soil surface in the Fall of the year. If the soil surface is disturbed, the seed may then germinate. The general rule of thumb is that seeds should be planted as deep as the seed is thick; larger seeds deeper than smaller seeds. When planting many different seeds at one time, it is best to spread all seeds on top of the newly tilled surface and then lightly till the soil after planting the seeds. Packing the soil after the tilling will ensure that the seeds are in contact with the soil. Seeds will germinate but many will not flower the first year and it may take several years before some species flower. The important point to remember is not to till the site again as you will destroy the perennials. There are some mechanical planters available that drill the seeds into the soil. For large scale plantings, you may have to use this type equipment and possibly even consider aerial planting from airplanes.
Transplanting and rescuing work best in January and February but can be done at other seasons if watering can be used to supplement rainfall. When using transplants, dig a hole as close to the size of the ball of roots and soil of the potted plant. Remove plant from pot and disturb the soil of the root mass; some even recommend removing soil so that you have a bare root plant. Place the plant in the hole and replace the soil around the root mass. Pack the soil down around the top of the plant. You may want to cut back the stem so as to reduce water loss and increase the chances of the plant surviving. When rescuing plants, dig a hole to match the size of the clod. Place the clod in the hole and place dirt in the space between the clod and the side of the hole plus some on top of the clod.
A Recommended Twist to Planting
Most people want instant gratification in almost all aspects of life including prairies so a good way to plant prairies is to include seeds of one or a few annuals in the original seed mix that of necessity will be dominated by the seeds of perennials, and to transplant into part of the prairie site. The annuals will grow and flower the first year and a few will repeat the second year and fewer still the third year etc. The transplanted perennials will also flower the first year and start to increase in the size by growing underground parts. There will be more of these the second year and still more the third year etc. In the meantime, the perennials planted by seed will grow the first year and most will not flower but some will start to flower the second year etc. Using this method keeps the prairie from being real drab the first few years.
Maintenance of the Prairie
Remember that most prairies are in part maintained by fire so try to include fire in your plans. If fire is absolutely not an option, then use mowing once a year. The best and only time to mow would be during the dormant season. Since the herbaceous perennials are underground, the mower can be set at the lowest level possible. The mowing would simulate the action of the fire by removing the dead growth from the previous year and most importantly, cut back the woody plants. Repeated mowing should keep the woody plants under control but some woody species may require chemical or mechanical control.
Annuals will be common the first year but will decrease in numbers dramatically the second year and will steadily decrease in succeeding years. If the area is tilled or disturbed, annuals will reappear. To hasten the development of the prairie, you may use chemical or physically remove unwanted woody and especially herbaceous species. If you are patient, the native prairie species will eventually force out the other nonnative and non prairie species over a period of time.