BU-07447
2005

Native Plants for Sustainable Landscapes: Establishment and Management of Lakeshores and Gardens

Obtaining plants and seeds

As native plant landscaping increases in popularity, more nurseries are propagating and selling native plants locally and by mail. It is best to buy plants that are propagated from plants native to Minnesota since they are better adapted to our region. Although it may be tempting, do not remove plants from the wild unless you have a permit.

Plants can be raised from seed. Seeds may be purchased from suppliers, or collected on private property with the landowner's permission, as long as this can be done without harming wild populations. Seeds from endangered, threatened, or special-concern species must not be collected, and these species are not included on the plant lists in this publication.

Most seeds of native plants require a cold treatment before they will germinate. You will likely need to mix the seeds with damp sand and refrigerate them for two months. Alternatively, seeds can be planted in pots in the fall, covered with mulch, and left outdoors for the entire winter in a protected, shaded spot, or in an unheated garage. Uncover the pots in the spring and keep them watered.

Planting prairie, woodland and wet meadow

Remove existing vegetation before planting to increase success. Roots of existing plants can otherwise compete with tender young roots of newly planted vegetation.

Sod and weeds can be removed by hand, by rototilling, or by covering them with plywood and/or black plastic sheets for two months or more. In areas that are rototilled, care must be taken to prevent erosion and reduce runoff. Alternatively, herbicides can be used, but care must be taken to prevent herbicides from entering the water. If herbicides have been used, wait two weeks before planting.

Areas which are overgrown with reed canary grass or purple loosestrife are particularly difficult to plant due to the intense competition from these weeds. These plants may be removed mechanically or with the use of herbicides.

It is best to plant on a drizzly or overcast day. You can improve the success of your planting by:

• not allowing the plants to dry out before planting
• providing ample room in each planting hole
• not planting too deeply; keeping the plant at the same level it had in the pot
• protecting the plants from strong winds
• mulching before planting, which is much faster than mulching after planting
• watering immediately, then daily for two weeks
• continuing to water new plants until they are well established

For spacing, one plant per square foot is recommended, but denser plantings will cover the ground faster, especially on slopes. Most plants grow slowly at first as they develop roots, so small transplants yield more rapid results than direct seeding. Three years may be needed for some plants to mature.

Direct seeding of prairie and wet meadow plants may be used to cover large areas. Spring and fall are the best times for seeding in Minnesota. You can broadcast seed by hand or use a spreader on prepared soil. Ensure good seed-to-soil contact by lightly raking the seed in, then rolling with a lawn roller. Cover the seeded area with a light mulch of weed-free straw.

Planting the emergent and submerged zone

All aquatic areas of lakes and areas below the ordinary high water level are regulated by the Minnesota Department of Natural Resources. A permit is required to plant or remove vegetation, to use herbicides, and to install wavebreak structures.

Even with a permit, you need to be aware that revegetation in the emergent and submerged zones is not as well researched as are prairie plantings. Extra care must be taken to prevent sediment from entering water by placing straw bales or filter fences between the planting area and water.

Undesired vegetation in the emergent zone can be removed by hand or by heavy mulching with plywood or black plastic left in place for two months before planting. Wetland soils should not be tilled. Herbicide use is not recommended and requires DNR approval.

Areas with heavy wave action, whether natural or due to boat traffic, may require wavebreaks such as brush bundles, coconut fiber logs, or plywood held in place with a PVC frame for a period of time so that plants will not be washed away before they take root. Plants can be planted directly into coconut fiber logs or biodegradable erosion mats, and a list of possible suppliers is provided on page 18 of this publication.

Remember that different bottom sediments influence wave action. Area with sandy bottoms often have higher wave action, which could be reduced if aquatic plants colonize the area.

In the emergent and submerged zones, using plants, rhizomes (underground stems with buds) or tubers, rather than seeds, is recommended. Seeds of most emergent plants will not germinate under water, so unless the water level can be controlled, you must wait for a dry period to plant them.

Plants for emergent and submerged zones should also be planted as soon as possible after you receive them, and should be kept cool and moist until they are planted. Emergent plants must have some of their leaves above the water in order to start growth, although they may spread into deeper waters later. Do not clip or prune them. Tubers of arrowhead, bulrushes, and waterlillies need to be planted by pushing the tubers firmly into the mud or sand.

Plants, tubers, and rootstocks may be held in place by staking them down, tying them to bricks using cotton string, or placing them in cheesecloth bags weighted with rocks. Some suppliers sell tubers, rhizomes, or plants with weights attached. These can be dropped directly into the water in areas protected from wave action. As roots develop, plants will be held in place naturally.

Long-term sustainable management

Watering may be necessary during the first season of a new planting, even in areas close to a lake. In general, native plants will gradually out-compete any weeds present, but it is best to remove as many weeds as possible by hand before they develop deep roots.

Once established, prairie restorations may be mowed or burned in fall or spring to prevent invasion of trees and exotic grasses, but burning requires a permit and you must check both local ordinances and with the Minnesota Department of Natural Resources. Do not burn for the first three years after planting. Once the restoration is well established, burning every three years will maintain it. In urban areas where burning is prohibited, mowing in early spring can partly mimic fire conditions.

Components of sustainable management

There are four primary components to sustainable management: placing plants in their correct micro-habitats, using low input lawn care, composting, and applying integrated pest management practices.

Use plants suitable to the microhabitat - Every site contains different microhabitats due to light and moisture differences. The use of perennial plants, especially natives, which are adapted to each micro-habitat, reduces the need for fertilizers, herbicides, and pesticides. Replanting is typically not necessary since these plants persist for many years.

Low input lawn care - Limit lawn fertilization to low-phosphorus fertilizer applications in August and September. Water the fertilizer lightly into the soil or vegetation. Do not allow fertilizer to enter the water as it will increase the growth of algae and aquatic plants.

Longer grass survives better in the shade and during hot dry weather. Weeds are slower to invade longer grass, so mow to a height of 3 1/2 inches. If grass is tall, only take about one-third off the height at a time until the 3 1/2-inch maintenance level is reached. Leave grass clippings on the lawn, but keep them out of the water.

Remove weeds by hand rather than applying herbicide. In the shade, instead of grass use shade-tolerant species of ground cover.

Composting - Compost yard wastes and add the compost to gardens to improve soil structure, hold moisture, and provide a low level of nutrients. Purchased mulch retains water, but does not provide the same soil structure benefits as compost. Leave twigs, leaves and other litter on the ground under trees, but not on lawns. Stems and branches will slow the rate of runoff during spring snowmelt.

Integrated Pest Management (IPM) - When pest problems develop, control is best accomplished by Integrated Pest Management. IPM is a decision-based management system based on timing pesticide applications when insect pests are in earlier stages and most vulnerable. Biorational pesticides such as soaps, horticultural oils, Bacillus thuringiensis (Bt) bacteria, and Beauveria fungus are favored over conventional pesticides. These biorationals conserve beneficial insects such as predators and parasitoids.

Conventional pesticides should be used on a limited basis only when necessary, to avoid killing beneficial insects. Beneficial insects are predators, parasitoids, bees, and butterflies. Predators and parasitoids reduce pest insects. Bees and butterflies pollinate plants and add beauty to the landscape. Table 3 shows some examples of beneficial insects that utilize native plants.

Table 3. Some examples of common beneficial insects: predators, parasitoids and pollinators.

	Odonata: adult dragonfly, predator		Odonata: aquatic nymph dragonfly, predator
	Coleoptera: ground beetle, predator (eating a caterpillar)		Neuroptera: larval lacewing, predator
	Hymenoptera: adult parastic wasp, parasitoid		Hymenoptera: adult parasitic wasp, parasitoid (laying egg in an aphid)
	Lepidoptera: swallowtail butterfly, pollinator		Lepidoptera: a spinx moth, pollinator (on a Michigan lily)

Over the long term, less maintenance will be required as a sustainable landscape of native plants continues to develop. You can chronicle the growth and evolution of your landscape, and the progress of plant and animal populations, by taking photos and recording observations of the site after planting, and then regularly for several years. Some plant species will thrive and others will prove unsuited to the site and vanish. Birds and insects will arrive and leave as the seasons change.

Always be aware of changes that may cause erosion and be ready to prevent them. Sustainable landscaping with native plants will enhance your enjoyment of your property and increase its value for years to come.

Produced by Communication and Educational Technology Services, University of Minnesota Extension Service.

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