660 Market Ave., Grand Rapids

Constructed and planted September, 2002

The River of Stars rain garden was constructed by the City of Grand Rapids. Garden design layout and planting were coordinated by Rain Gardens of West Michigan. This is the first of our project demonstration sites.

The River of Stars rain garden got its name from a song. The garden is next to the Grand River, which flows to Lake Michigan. The garden has a "river" of white-flowering plants running through the center.

Runoff comes from the surrounding slopes of turfgrass and tree islands, and from half of the roof of the building next to the garden.

What to do with those wet spots

This garden is a great example of what to do with one of those troublesome wet spots that occur in built landscapes. Before the rain garden, the site was an area of compacted clay soils where a pond would form. Water often lingered long enough to grow mosquitoes. Lawn mowers would get mired in the muddy spot, and the lawn grass couldn't survive there. Instead, the spot supported deep clay mud and typical facultative wetland species such as sedges, rushes, and purple loosestrife. 

A drain is often installed in the bottom of a problem spot like this to carry water that accumulates (and lawn care products that run off turfgrass) directly to a storm sewer. The city wanted instead to make this an example of how to use landscaping, instead of expensive infrastructure, to solve this kind of problem.

Construction

Because they wanted this garden to function well, and the surrounding impacted clay soils had the imperviousness of cement, they excavated the garden site out to a depth of five feet. A foot of round gravel was placed in the bottom as a reservoir. The round gravel provides space to store excess water at the bottom of the garden. The gravel was covered with landscape fabric, and then the site was filled in with well-rotted compost. This use of pure compost is unusual; typical replacement soil consists of a mix of 50% sand, and 25% compost/25% topsoil. The compost has worked extremely well for a garden base, and is kept from becoming too soggy by the gravel reservoir.

Planting the garden

The site was planted by city employees, Rain Gardens of West Michigan, and RiverMaid Design. We laid out the garden plan (about 25' X 35') on graph paper, then transferred the grid layout to the garden with string. The plants were then put in place on the grid, and we planted the site by moving from one end of the garden to the other.

The plants

The plants used were primarily large plants with extensive root systems, gallon sized mature perennials. This gave the garden a jump-start, and we had blooms the spring of 2003. Some plugs (small perennials less than a year old) were used, and those matured and bloomed the following year.

Plants selected by RiverMaid design bloom in a lovely succession from early spring to late fall. Rebecca Shilt chose a combination of native prairie species, other natives, and traditional landscape plants for this site. The design is formal, with plants in groups. There is winter interest in the garden from grass flowers and plant materials that are left intact in the garden. This provides wildlife habitat and seeds for wildlife in the area.

The results

By 2004, the garden was growing well and had become a favorite spot for the people who work at 660 Market Ave. They installed an arbor which will be planted this summer, and placed two chairs by the arbor. Stepping stones in the garden allow easy maintenance and access to view the plants.

The area has been transformed from a soggy maintenance problem into a lovely perennial garden that people like to visit. It has been featured in several recreational garden tours and on stormwater management demonstration tours as well. People were so interested, they even visited it in the winter with snow on the ground. And we have to admit, it was beautiful then, also!

Lessons learned

Weeding is essential

We learned from this site that the first year of a rain garden, weeding should be done biweekly. In one wet spring month when we were too busy to attend the garden, a zillion weeds sprang up in the fertile soil. It took several days to pull them out. They loved that compost!

Instructions are needed

When planting the garden, work with small groups of people (no more than three to six at a time). Every new group that joins the planting needs the same instruction. Demonstrate how to remove the plant from the pot, break up the root ball, and place it in the soil. Let them know that dormant plants are not dead, and should be planted, not thrown away. Remind them not to step backwards on the plants already planted. And be sure they know that the garden is a design, and plants should be planted in the spot where they are placed, not just anywhere.

Label the plants

People are not familiar with native plants, and some are not familiar with any plants at all. Labelling can save plants from being weeded out by people who do not recognize them. Descriptive labels can inform and educate people, and protect your plants.

Some plants (Mistflower, for example) break dormancy late and can be accidentally buried by people mulching the plants. Labels are helpful for that as well.

Maintenance manuals are helpful

Many of the people we have involved in rain garden projects do not know much about gardening or plants. An illustrated, scheduled maintenance manual is extremely helpful, a lesson learned also from other rain garden projects.

An example: One important point for maintenance is the depth and placement of mulch. People tend to bury the plant crowns with mulch, which causes the plant to become diseased. A manual can instruct rain garden owners on proper mulching techniques.

People love their rain gardens

People who are involved in creating a rain garden where they work continue to be very involved in the future health, care, and enjoyment of their garden. All that sweat equity leads to great stewardship!

Some plants are too enthusiastic

Gooseneck loosestrife is an example of a wonderful plant that can't curb its enthusiasm. It is multiplying into other areas of the garden and will need to be divided and trimmed back ("beaten into submission", said some people) yearly. Some plants should not be used in a rain garden that will not get the kind of loving attention that this one does!