Establishing grasses and wildflowers with plants
For the best results, the soil should be completely free of grass and weeds before planting. The best way to do this is by killing the existing vegetation either organically or with a non-selective herbicide such as glyphosate. At least two herbicide applications are usually required to eliminate existing vegetation. If weeds germinate after the “last” application, spray again on a warm sunny day 10 days prior to planting.
We generally recommend that you do not amend the soil when planting prairie natives. Rich soil encourages these plants to grow too tall and fall over. Lean soil, though harder to plant in, produces better results. Spacing varies by species but 1.5' centers is a good average for narrow species such as Silky Aster (Aster sericeus), Wild Quinine (Parthenium integrifolium) and Little Bluestem (Schizachyrium scoparium), 2 – 2.5' centers for wider species such as Purple Coneflower (Echinacea purpurea) and Prairie Dropseed (Sporobolus heterolepis) and 3' centers for large grasses and creeping plants such as Eastern Gama Grass (Tripsacum dactyloides) and Purple Poppy Mallow (Callirhoe involucrata).
Plants can go in the ground any time from early May until late September. It is generally best to water the planting after it is installed and apply a pre-emergent herbicide. We have successfully used Snapshot and Pendulum for pre-emergent weed control. Mulching just after planting will help conserve moisture and keep weeds at bay the first year. You may have to water several times the first year or two after planting to get plants established. To establish durable, deep root systems water slowly and deeply rather than frequently and shallowly.
A soaker hose is an easy and efficient watering method. Water drips slowly onto the soil right around plant roots for several hours. All of the water soaks directly into the soil and down to plant roots without any waste. The soil around plant roots should be moist, but not soaking wet, the first two weeks. For the next two weeks or so, water when the soil 2 inches below the surface is dry to the touch. After that, check the garden soil periodically and water if the soil 4 inches deep is dry.
Your planting will fill in during the second and third year and will not need additional mulch or water from the third year on.
Establishing grasses and wildflowers with seed
For the best results, the soil should be completely free of grass and weeds before planting seed. The best way to do this is by killing the existing vegetation either organically or with a non-selective herbicide such as glyphosate. At least two herbicide applications are usually required (one in spring and one in late summer) to eliminate existing vegetation. If weeds germinate after the “last” application, spray again in late October or early November on a warm sunny day.
If a layer of thatch (dead vegetation) covers most of the soil, burn or mow and rake the area so your seed will come in contact with the soil when you put it down. Sow the seeds on the surface evenly in late November through mid-January and let freezing and thawing take them down into the soil. Many of the seeds will germinate during March and April but the warm season grasses won’t germinate until May or June when the soil temperature reaches 60 degrees F.
If you are fall seeding on an erosion prone site, plant a nurse crop of annual rye or oats by mid September to stabilize the soil. The nurse crop will be killed by cold temperature but the dead roots will hold the soil in place through winter and will still allow the native seed to germinate in spring.
Seed can be sown in a number of ways, depending on the size of your area. Hand broadcasting works well in areas of one to two acres. If you select this method, mix the seed evenly with one bushel of inert material for every 1,000 square feet of planting area. Slightly damp sawdust, peat, vermiculite, potash, ground corn or other inert material makes it much easier to evenly distribute the seed. Take one-half of the total mix and distribute it evenly over the entire area. Then, take the remaining half and spread it over the same area, walking perpendicular to your first pass. Roll the site with a roller or drive across it with a car or truck to firm the seed into the soil. Do not roll the site if the soil is wet.
When planting areas over two acres in size, use a broadcast seeder mounted to an ATV or tractor. Mix the seed with inert material as previously described. Talk with your Private Land Conservationist about the type of planting method best suited to your needs. They can also help locate suppliers that rent equipment or contractors familiar with seeding native plants.
What to expect
Container-grown native plants put in gardens with no weed competition and adequate water usually put on astounding growth the first year and will be fully mature by the third year. Most native trees, shrubs and vines planted from containers also establish quickly. However, native plants from seed take longer to get going. Wildflowers and grasses planted from seed spend the first year, and sometimes three years, sinking their extensive root systems into the soil. For this reason, you might not see a lot of top growth right away. Be patient. These large root systems are what sustain the plants through drought and harsh winters.
Taking care of natives in your home garden
As with any garden or landscape project, it’s important to maintain your planting(s) to keep them looking their best. The good news is that, after they are established, most native landscapes require less maintenance than their non-native counterparts.
Mulch is a material that is layered on top of the soil to conserve moisture, to moderate soil temperature, and to keep soil from crusting during drought and compacting from prolonged rain. It is also a tremendous time and labor saver because it greatly reduces the need for weeding. Mulch shades the soil, preventing many weed seeds from germinating. Weeds that do rise to the surface can be easily pulled.
Organic mulches are ideal because they break down over time to improve the soil structure. Materials such as compost, well-rotted manure, shredded leaves, pine needles, and fine textured bark chunks are good choices. You can make your own mulch by composting or by using a power tool called a shredder-chipper that turns yard waste into mulch.
A 2-inch layer of mulch should be spread over weed-free beds after plants are installed and, if you use them, after soaker hoses have been laid in place. Be careful to keep mulch pulled away from the crowns of plants. Crowns that are covered with moisture-holding mulch tend to rot. Do not mulch areas that are being established by seeding. Organic mulches can be reapplied the first couple of springs as long as you aren’t suffocating plants. Your plants should be well enough established by the third year that you don’t have to mulch if you don’t want to.
The key to long-term weed control is to be sure that your garden is free of weeds before you plant. After digging the soil in your planting area in early spring, wait a few weeks for weed seeds to germinate before planting. When unwanted seedlings arise, stir the top inch of soil and cut them down. Leave the lower soil, and the weed seeds imbedded there, undisturbed. Do this two or three times prior to planting and you will save yourself many hours of work later.
If your garden is weed free at planting time and you apply an organic mulch to keep new “weedlings” from germinating, you will be able to keep up with weeds easily by patrolling the garden once or twice a week. It’s easy to pull young weeds before they go to seed or start spreading. A sharp hoe and putty knife or fishtail weeder, sometimes called a dandelion fork, are great weeding tools. Use the hoe for shallow rooted annual weeds. Use the putty knife or fishtail weeder for deep rooted perennial weeds, being certain to dig and remove the entire root. If you don’t get all the root, it’s likely that the weed will regenerate from parts left in the soil. Grass and wildflower plantings that are a safe distance from houses and other structures can be burned in late winter to control weeds.
Spacing your plants closely also helps control weeds because the foliage of neighboring plants shades the ground and crowds out invaders. You need to be especially diligent about weeding in the spring when newly emerging natives have not yet had a chance to canopy over the ground.
DON’T! Our native wildflowers and grasses turn into “floppers” if they are force fed fertilizers.
Once natives are established, they require minimal maintenance. That’s one of their big advantages: The plants simply keep coming back each growing season. However, depending on how you want your plants to look you might want to use a few of the grooming techniques described here.
Deadheading is a fierce term for removing faded flowers. If left to their own devices, many natives bloom gloriously for a short period of time. Then they stop flowering and set seed. Deadheading interrupts this cycle. If faded flowers are removed before they set seed, many will send out another flush of blooms to try to complete the reproductive cycle. The blooms in the second display may not be as large or as numerous as the first, but they are certainly worth the effort. Other natives that bloom over an extended period of time benefit from deadheading because it increases the number of flowers that are produced and the length of time over which they are produced. Deadheading also gives you some control over flowers that can be invasive because they self-seed. Purple Coneflower, Missouri Black-eyed Susan, Coreopsis and Garden Phlox self-seed with abandon if they aren’t deadheaded.
Basically, there are two places to make deadheading cuts. With flowers that have leaves along the bloom stem, cut just above the point where you see a new shoot or bud emerging. This is usually in the axil of the set of leaves closest to the old flower. To deadhead flowering natives that don’t have leaves along their flower stems, make the cut at the bottom of a flowering stem near the base of the plant.
Cutting back is a technique used to keep leggy plants more compact, to promote new foliage growth, or to coerce plants to bloom repeatedly. Sometimes you can avoid staking tall plants that are prone to flopping like tall Asters and tall Goldenrods if you cut them back by about one-half in early summer. This keeps plants shorter than normal. Still other plants like Columbine and Yarrow should be cut back to the basal foliage (leaves that grow from the crown or base of the plant) after they finish flowering. This will promote lush new foliage growth and, sometimes, another round of flowers.
Shovel dividing is a maintenance practice that keeps vigorous perennials in their allotted space. As you stroll the garden looking for weeds and spent flowers, keep an eye out for natives that are encroaching on their neighbors. When you spot plants that are getting out of hand, insert a round-point digging shovel into the plant with the back of the shovel against what you want to keep and the front of the shovel next to what you want to remove. Pull back on the shovel and pop the unwanted portion of the plant out of the ground.
Preparing for Winter
If you are growing natives that are winter hardy in your area, there’s really very little to do to get the garden ready for winter. Once frost hits, the top growth of most wildflowers turn brown and die back to the ground. When this occurs, use hand pruners to cut off the dead stems, leaving only the bottom 2 or 3 inches. Alternatively, you can leave the old flower stems standing for the many winter birds that will feed on the seed heads through winter.
Maintaining larger scale plantings
Most large scale plantings are done with seed. Weed control is very important the first two or three growing seasons. Most native wildflowers and grasses grown from seed don’t get more than 6 inches tall their first year. Weeds, on the other hand, generally grow much faster than the desirable plants. During the first two growing seasons, mow your planting when the natives reach 6 inches in height and the weeds reach 8 to12 inches in height. Don’t let the weeds get taller than this. Weeds over 12 inches tall will shade out your seedlings and the mown weed material will smother smaller, desirable plants when you finally do mow.
You can expect to mow once per month during the first year. Mowing doesn’t harm native plants but it does prevent weeds from going to seed, thereby reducing weed problems in subsequent years. String trimmers work quite well on smaller areas while flail-type mowers, which chop weeds so they dry quickly, work best on large areas.
In the spring of the second year, mow the planting to the ground and remove the mown material by raking, if possible. This will give your native plants a good jump on weeds. Mow weeds in late spring or early summer. Biennial weeds may be especially troublesome in the second year. Mowing them back when they are 12 inches tall and in full bloom will usually kill them with little damage to the prairie plants.
From the third year on, annual mowing and removal of plant debris or burning will promote vigorous growth of your native plants and keep weeds under control. Because most prairie plants are warm season plants, they grow more quickly and produce more flowers and seed when the soil is bare and can warm quickly early in the season. You can mow or burn anytime between November and late February.