Prairie Garden Maintenance Guide

volunteers pulling weeds

The Little Prairie on Campus, which began in 2017, is a 2,000 square foot biodiversity island that is home to over 20 species of native plants. It’s located just South of the School of Public Health, on the western wall of the Center for Structural Biology.

The prairie was made possible with support from the National Fish and Wildlife Foundation, in the form of a grant to preserve and restore natural spaces in the Chicago region. The original goal of the prairie was to divert stormwater,  but it has become a beacon of a pollinator friendly habitat for bees, bats, and butterflies as well. Additionally, It houses bunnies, birds, and other native wildlife.

The Little Prairie on Campus is an established prairie and should only need minimal annual maintenance to continue to thrive. Through the properly timed and carried out utilization of the methods described here, the prairie will return beautifully year after year.

Daily Maintenance Guide

student intern squatting by weeds with shovel

Spring and Summer

Weeding

Until the prairie is fully established, it will need regular weeding to promote healthy growth. Weeds hog root space, block out the sun for seedlings, and divert valuable nutrients away from established and unestablished plants alike. Weeding regularly negates those issues as well as tills up the soil for easier watering and planting.

A weed is defined as a wild (not deliberately cultivated) plant growing where it is not wanted. They can be identified with the help of the staff at the Greenhouse or using the Weed Identification guide, then removed by the root, using work gloves and spades. They can be piled under the shrubs against the Western wall of the Center for Structural Biology for the grounds department to collect. While not technically a weed, any common grass found within the garden should also be removed.

Watering

The equipment needed to water the garden can be found in the Office of Sustainability, located in the Paulina Street Building, and includes a hose and a key. The hose can be found in the supply closet and must be connected to the water spigot that is located on the Eastern wall of the School of Public Health. The key can be found in the office and is necessary to turn on the spigot.

Established prairie plants will get all of the water they need from Illinois’ natural rainfall, however, regular watering is essential for the survival of newly planted seedlings.

Pest Management

Discoloring, dead-spots, and stripped leafs could all be tell-tale signs of an underlying pest problem. As a first defense, prune off leafs showing symptoms then attempt to locate the source of the issue and consult Pest Management for The Home Landscape for solutions. If these issues persist or the issue can not be identified, contact the University of Illinois Extension for assistance.

Planting Seedlings – Spring

To plant a seedling, dig a hole slightly larger than its base and deep enough that the roots are just below the surface but not exposed. Place the plant into the hole, cover the roots with loose soil, and gently pat it into place. Mulching is recommended for spring planted seedlings, as it holds in moisture and reduces weed germination. Seedlings can be planted in the spring, summer, or fall, depending on availability.

For additional information see Watering and Planting Seedlings – Fall

Culling

Certain desirable plants can become a nuisance in the garden by being aggressive and out-competing other plants. To identify an aggressive plant, assess its effects on neighboring plants, such as if it’s the only species growing in that section, it’s choking other plant’s roots, and if nearby plants are wilting. When in doubt, contact the greenhouse with a photo of the section in question.

Once identified, culling, or the selective removal of plants, can be utilized to control overly aggressive plants.

Edging

The prairie is surrounded on three sides by Kentucky bluegrass, which tends to encroach on the garden. This can be managed by having the garden edged, cutting and removing the grass on the perimeter, by the Grounds Department annually. The Office of Sustainability is responsible for putting in an official work order with the Grounds Department and paying for the service.

Transplanting

Before the garden is edged, any desirable plants along the perimeter should be transplanted towards the center, to avoid being cut. The Plant should be dug up carefully by the root, using shovels and protective gloves, then replanted following the planting seedlings guidelines. Digging a wide perimeter around the base can help to avoid cutting the root by mistake.

Fall

Seed Extraction

In late summer or early fall, as plants begin to wilt and brown, the greenhouse should be contacted to assist with the collection of cuttings of flowering plants or seed heads. The cuttings can be dry-stored and the seeds removed at a later date.

Seed Casting

The seeds extracted from the cuttings may be used to grow seedlings for the following year or spread throughout the prairie in the fall to germinate naturally over the winter months. The seeds should be slowly hand-cast across open spots in the garden to ensure an even distribution. Water regularly until germination.

Planting Seedlings – Fall

Each plant has an optimal transplanting season and specific planting preferences. Consult Prairiemoon.com and/or the greenhouse before deciding which season to hold a planting and where to place each plant within the garden.

To complete a fall planting, follow the same instructions found in the Planting Seedlings – Spring section of this guide.

Seedlings planted in the fall do not need to be mulched, as weeds are unlikely to germinate and the plant will soon go dormant for the winter.

Long Term Maintenance Guide

Aggressive Anise Hyssop plants dominate over other tall grasses

Management Methods

Without regular maintenance, the prairie would become overgrown and overburdened with undesirable weeds and plants. In order to maintain the health of the prairie and divert these issues, the university must choose and then regularly enact one or more of the various prairie management solutions available. Listed here are some of the possible options.

Controlled Burning

Controlled burning is the most well-known and widely utilized method for prairie growth management. It’s recommended that randomized sections of the prairie be burned every two to three years in order to maintain plant and animal diversity. Burning any more often or burning the entire garden may lead to a reduction of insects and other valuable pollinators such as bees and butterflies.

Burning is a natural way to eliminate low-lying weeds as well as other overly aggressive plants. As an added bonus, the burned organic matter creates a blanket of warmth and nutrients for establishing plants, while blocking out any future germinating weeds.

Despite burning being the most popular management method for prairies, it is not necessarily an option that is available to the university. Due to the fact that the Little Prairie on Campus is in a dense urban area, is sequestered against a wall, and is surrounded by Kentucky Bluegrass, it most likely would not be possible to pass the strict regulations to secure the necessary permits for a burn. Therefore, an alternative method or methods must be utilized in its place.

Mowing

Mowing is a method used to control the germination of weeds in the first two years after seeding, to contain the growth of weeds and cool season grasses after the third year of establishment, and to continuously prevent invasion by surrounding foliage.

Mowing should take place between April 10th and May 10th or after the plants have gone dormant in the mid to late fall. Only sections of the prairie should be mown while others are spared to mimic the randomization of a burning. The most efficient method of mowing is the hand held string trimmer (weed whacker). Benefits of the string trimmer method include: mowing at a variety of heights for each plant’s individual needs, laying down the cut material gently, without clumping, to create a blanket of nutrients, and the ability to be used in situations where traditional mowers cannot, such as directly against a wall.

The Little Prairie on Campus is in its third year of growing and is thus considered an established prairie. After the first two seasons, the maintenance necessary to upkeep the health of the prairie using this method decreases significantly.

First Year

Mow sections of the prairie seeding to 6in  in height, before they grow to 16in, to keep back fast-growing annual weeds. Allowing them to grow any higher before cutting, can bury and suppress the seedlings beneath the cut material. Mowing before weeds set seed also reduces problems in following years. Mowing should take place around three to four times in the first season.

Second Year

Mow sections of the prairie to 12in in height in mid-late June, when most are in full bloom, to prevent seeding and re-infestation. This is critical to long term success of the prairie by controlling aggressive weeds before they are firmly established. Weeds that grow back and flower a second time should be cut back to the ground using pruning shears or carefully pulled up by the roots.

Third Year and Beyond

The third year of growing is when controlled burning should be initiated. As burning is not an option, mowing and raking the cut material can be substituted to mimic the effects of burning and is nearly as effective. Mow random sections close to the ground, right down to the soil surface if possible. Raking off the cut material after mowing helps to expose the soil and encourages more rapid soil warming, favoring the heat-loving prairie flowers and grasses.

Selective cutting

Selective cutting is a method where undesirable weeds or plants are cut, dug up, and removed from the prairie by hand. Each plant would be individually evaluated on its health, its relation to surrounding plants, and whether or not it is desirable. This will determine whether it is left to grow or it is removed in a very similar process to weeding. Additionally, this method allows unhealthy sections of otherwise desirable plants to be carefully removed, thus re-establishing the good health of the plant.

While this is a labor intensive and slow moving process, it is the most precise method of removal available and the least likely to harm desirable plants. It’s best to undertake this method before weeds begin to set seed to avoid future germination, however, this method can continue throughout the entire growing season and be used in addition to the mowing method.

It’s imperative that the plants removed by this method be dug up with the entire root to avoid regrowth. Excess soil should be shaken off root ball and left on-site

Future Plantings

Recently, a plant called anise hyssop had become a “weed” / pest because it is non-native to Cook County and was brought to the prairie by mistake. It has suppressed other plants in the prairie and has been continually maintained since then.

Strategies for Prevention

For any future planting that may occur in the prairie caution must be taken in selecting which plants should be introduced. While a plant may be native to the state or surrounding areas or be physically appealing it may affect the prairie negatively if the conditions allow it. Plants show signs of being invasive like quick growth, and  prospering while other plants in the prairie lose out on nutrients and die off. In order to keep invasive plants from becoming a weed pest and suppressing the growth of other plants in the prairie research on which county it is native to must be done.

Preventative measures include making sure to only choose native plants for the prairie, filling the disturbed ground with native plants, and being vigilant with removing weeds that are present. When planting is not possible, spreading seeds may also prevent weeds and plants acting as weeds from regrowing in disturbed ground. Doing a soil test for high nitrogen levels before the use of fertilizer also helps prevent the growth of weeds as they are used to high nutrients. Constant monitoring of the prairie and the plant species that are introduced aid in the prevention of invasive species from becoming a weed pest in the garden.

Research must be done on any plant before it is introduced to the garden to insure there are no further issues with plants that become invasive. There are many websites that provide lists of plant species that are native to Cook County including the United States Department of Agriculture (USDA).

Weed Remedies

Gaining control of weed pests after they have already been introduced to the prairie can be tricky however, there are a variety of approaches that may help remedy the problem. There are many kinds of invasive species and they require different methods for removal. Invasive species may include ground covers, annuals, biennials, perennial forbs, shrubs, bushes, or trees. Common and effective management methods may include physical, chemical, biological control, grazing, or burning.

Each type of weed pest can be managed and controlled by a combination of the methods listed below as prescribed by assessment. Creating and following a land management plan for weed remedies and removal is a great way to keep track of the helpful steps to take when dealing with a weed pest in the LPoC.

Physical methods

Physical management methods include pulling, hoeing, tilling, mowing, cutting, stabbing, and many others in order to remove weeds and their roots. Deadheading, removing the seeds, on plants that have become invasive is also effective with plants that are hard to dig up. Weed whacking may also be considered in these circumstances followed by laying down wet cardboard and mulch to prevent regrowth.

Physical removal methods can be done by pulling or digging up in the spring and fall and can be done with a shovel or hand with the extraction of the root.

Leaving the soil to dry helps make sure the remaining roots desiccate. Planting native plants in their place can also prevent their regrowth. Mowing, weed whipping, or livestock grazing may help stunt the growth and slowly dry up the roots. Smothering may also help by using a newspaper or cardboard for several inches of mulch to block out light and air from weed pests and suppress their growth.

Chemical methods

In cases that it is necessary to use herbicide cautiously and read the direction on the labels before using as there is a risk of putting native plants in danger unintentionally. Chemical methods include herbicides, however they require the appropriate knowledge on how to select and apply them properly and the risks of using it. Concerns regarding any environmental contamination and harm are why the Integrated Pest Management (IPM) was developed to promote synthetic pesticides in a combination of other methods to reduce harm.

Biological controls

Biological controls are meant to re-invite invasive plants to enemies in order to restore the natural balance and reduce the dominance of the plant. Using one organism to control the growth of another plant organism can be used to fight weed pests.

Other methods not used at UIC

Grazing

Grazing is used as a way to control weed pests by using domestic livestock during certain seasons. Prescribed grazing can be beneficial in controlling invasive plant populations in some situations where it might be the best option.

Burning

Burning is the last method used but is dependent on many variables for it to be considered for each situation and invasive species. When it is prescribed they are set under controlled conditions and are most successful when they mimic natural fire patterns in the habitats that are used to wildfires.

The Prairie's Pollinator Friends

Monarch Caterpillar

Monarch Caterpillar

Danaus plexippus

Red admiral butterfly

Red admiral butterfly

Vanessa atalnta

Red admiral butterfly

Hoverfly

Syrphidae

Ladybird beetle

Ladybird beetle

Coccinellidae

Pollinator Friendly Plants

Lance-leaved coreopsis

Lance-leaved coreopsis

Coreopsis lanceolata

Foxglove beardtongue

Foxglove beardtongue

Penstemon digitalis

Eastern bee balm

Eastern bee balm

Monarda bradburiana

golden alexander

Golden alexander

Zizia aurea

Invasive Weeds

Dandelion

Dandelion

Taraxacum

Creeping/ Canadian thistle

Creeping/ Canadian thistle

Cirsium arvense

Field bindweed

Field bindweed

Convolvulus arvensis

Horseweed

Horseweed

Erigeron canadensis

Photo Credits

Photos courtesy of Prairiemoon.com and the Office of Sustainability, Sustainability Internship Program Interns Heaven Silva, Katarina Fielder, and Megan Chrzas.

Additional photo credits: Vicky Barney – Bindweed, wildediblefood.com – Creeping Charlie