Tag Archives: Bloomington

Seasonal Raingarden Maintenance Practices

Seasonal Raingarden Maintenance Practices

Each season has a small list of tasks associated with good raingarden maintenance practices. By staying on top of maintenance each season, problems can be avoided and maintenance can be a small task compared to a major chore. By taking a few minutes to peruse the garden, major maintenance headaches can be avoided. What follows is an overview of maintenance tasks for each season so that readers may avoid these major problems and have a pleasurable gardening experience.


In the early part of spring, after the snow has melted and before new plant growth has started for the year, remove last year’s decaying growth. We call this decaying plant material ‘duff’. Duff is a wonderful thing to let stand throughout the winter months as it provides habitat and food for over wintering birds, helps to insulate the ground during the coldest days of the year, and it can provide visual interest in the garden throughout winter. Once temperatures begin to rise, however, new growth will start to peak up through the soil and it will be good to have last year’s duff out of the way. Not only does this help to warm the soil by providing a little extra sunlight, it can be a very exciting time visually as well. Fresh new green popping up in the garden is a most welcome sign of the warm seasons to come.

There are many species of weeds that will take advantage of this time of the year. Cool season weeds will start to germinate in the spaces between your desired raingarden plants. This is an excellent time for pulling these weeds out before they have a chance to become established. Once weeds, especially invasive trees, are established they become a real problem to remove. What could be 10 minutes spent easily hand-pulling tiny saplings becomes hours spent digging out substantial root structure. This not only makes maintenance a horrible chore, it affects the health and performance of the desirable plants in the garden.  Check out our blog for photos of cool-season weeds here.

Typically, your desired perennial plants will have a larger more distinct clump form, as well as a designed pattern in the garden. Raingarden design typically employs multiple specimens of the same species organized into groups. This can be another clue to help in identifying which plants will want to be left, because weeds are very randomly spaced.

Spring is a good time to assess your mulch. New mulch is more easily applied in the spring because plant material has not grown in the way. It is easier to see bare spots where mulch is thin and soil is peaking through. A good rule of thumb for mulch is to maintain a 3” layer. This will provide a good barrier against weeds and will help to keep the soil moist for desired plants. Remember to always use double shredded hardwood mulch in raingardens because it binds together and doesn’t float during large rain events. Check the Blue Thumb webpage for local distributors of double shredded hardwood mulch. It is typically available in bags or in bulk and can be either picked up or delivered for a small fee.

Spring is also an appropriate time for replanting any bare spots in the garden. There are many options for how to approach replanting. By following the planting plan for a project, gardeners can choose to use the same plant variety they have in the design and replace missing plants with what is shown in the plan. Another option is to replace with a different type of plant altogether. This is a particularly good approach if several plants of the same species have completely died out. Perhaps the designed plant variety is not as well suited as the designer had originally thought and some experimenting with a new variety might warrant better results. Replacing with a new variety can be a fun way for participants to further engage and take ownership of their garden. The Blue Thumb Plant Selector Tool can be an invaluable resource for choosing plants and learning a given plants’ characteristics.

Another great activity for spring gardening is the division of established perennials. This is an activity for more established plant material that has reached maturity. Many varieties of established perennial plants can be dug up completely from their home in the garden and then divided into smaller specimens for use in other areas of the yard. This can be particularly useful for gardeners wishing to add another raingarden to their yard without the expense of purchasing new plants. Spring is the best time for division and transplanting because it gives transplants time to establish new roots throughout the coming growing season. A good rule of thumb is to try and find specimens for transplanting just after the new foliage has begun to peak up out of the soil. With a little research online, gardeners can discern which of their plants would be most appropriate for division and use in other spots of their yard.


Throughout late spring and summer, it is a good practice to peruse the garden on a semi-regular basis. The longest I would go between visits would be two weeks. During these garden visits, keep an eye on your plants. Watch as they change with the season. As early blooming varieties fade, you may want to prune away any decaying plant material you find unattractive. This will typically be fine for your perennials and it is common practice for gardeners to do what is called “dead-heading”.  Dead-heading is simply the removal of any plant material which starts to decay during the growing season. This is really a judgment call on the part of each gardener, as it is a matter of aesthetic preference. Remember that perennials will bloom and then produce seeds on what were once blooming flower stems. Gardeners can choose for themselves whether or not they would like to keep this material around or not. Perhaps a gardener will want to keep seed heads around for the benefit of feeding birds or for the possibility of growing more of a particular variety from the newly developed seeds. On the other hand, a gardener may want to spruce things up in the garden to highlight the aesthetic of blooms that have yet to come. This is purely subjective and gives gardeners the ability to more fully engage in the look and function of their garden.

Summer is also a good time to keep a look out for invasive weeds that will take advantage of warmer temperatures. Typically we talk about “cool season” and “warm season” weeds because each season will have different weedy culprits. This is why it is suggested that gardeners plan to weed in spring and summer. If you get into the habit of perusing your garden on a semi-regular basis, then this may not even be necessary as you may have developed the habit of taking a couple of minutes to pull out the weeds as you go. This approach is hardly a chore at all and more like a pleasurable little moment of time spent in the garden.  Should it happen that this habit is not entirely working, then it is at least important to plan at least some summer weeding to avoid the headache of tree saplings getting to large for easy removal.


Autumn is a good time to get at any of the weedy invasives that you may have missed during the summer. Make sure to inspect the garden for any invasive trees or turf grass that has made its way into the garden. By now gardeners can start to think about how they would like to leave their garden for the winter. Many native and ornamental grasses and sedge species can be particularly beautiful during the winter months. There are also many varieties of perennials that look attractive after they have gone dormant and seeds from these plants can be a good source of food for over-wintering birds. Remember that “duff” can be left all winter and removed as part of spring maintenance, but it also possible to remove anything that may be unattractive in the garden over the winter months. It is an aesthetic judgment that gardeners can make depending upon their own preference.

Another good thing to think about in late autumn and into the winter months is pruning shrubs that you may have in your garden. Prune shrubs after they have lost all of their leaves and have gone dormant for the winter. It is best to prune no more than 30% of living tissue from any shrub at a time. Remember that pruning is strictly an aesthetic practice. Many shrubs look fantastic if left alone until they have reached their mature size, so research your shrub species to learn about their height and width at maturity. Ultimately, however, shrubs can be pruned to fit a gardeners aesthetic preference so fastidious pruning can be an activity that gardeners use to create a desired look.

‘Garden’ is both a noun and a verb

One final note regarding raingardens…a garden is a noun and a verb. It is a place in your yard, but it is also the act of caring for that place in your yard. It is often the case that raingardens are planted and then left on their own with no maintenance. This results in an unsightly, weedy mess that for all intents and purposes is not in fact a raingarden at all. To have a raingarden implies the action of gardening. Gardening is maintenance… It is the care required in order for there to be a garden. Remember that gardening is as much of a chore as one makes it. With a little bit of effort, gardening can be a very rewarding experience!!

Raingarden Maintenance: Plant Replacement and Establishment

As you may have read in our recent blog postGreen Streets for Blue Waters’, our two year project in partnership with the City of Bloomington just wrapped up. The project included the addition of 18 newly installed curb cut raingardens and a fabulous vegetated bio-swale.  After installations were complete, we were charged with ensuring these new practices are maintained by residents so they continue looking great and functioning properly.  When raingardens aren’t maintained they can fill with sediment, lose their ability to infiltrate water, get taken over by weedy species and lose their aesthetic appeal, which leads to poor public perception.  It’s an issue everywhere raingardens are installed, so making sure homeowners have the tools they need to maintain their gardens is no small task!

To kick off our maintenance education in Bloomington, each participant had the opportunity to meet one on one with Metro Blooms designer and maintenance expert Andrew Novak. Our hope with these visits was to instill a sense of confidence and ownership in participants as they care for their new raingardens. Gardening can be a very rewarding experience, both physically and mentally, and good maintenance is the most important aspect for ensuring the longevity and success of each garden.


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Green Streets for Blue Waters

Hello All,

We would like to take this opportunity to thank all of the participants of the Bloomington Green Streets for Blue Waters program for taking part in this important project and give everyone else a quick overview of all that’s been accomplished!

Over the last two years, Metro Blooms, in partnership with the City of Bloomington and the Lower Minnesota River Watershed District, worked with residents to design and install a vegetated bioswale and 18 curb cut raingardens in Bloomington neighborhoods that drain to the Minnesota River.

Bloomington GSBW 2013-14

Curb cut raingardens are uniq20140919_101426ue in that they not only capture runoff from the property itself but from the street as well.  The project area was selected because it is adjacent to the Minnesota Valley National Wildlife Refuge. Individual sites were selected based on site suitability and resident participation. In total, during an average year with 30″ of rainfall, the completed practices:

  • Treat stormwater runoff from 55.42 acres
  • Remove over 3,500 pounds of solids
  • Remove 8.5 pounds of phosphorous and
  • Infiltrate 1.9 million gallons of runoff

The solids and phosphorus removed would otherwise end up in the Minnesota River, causing algae blooms which deplete oxygen and diminish aquatic habitat when they decompose. The millions of gallons of runoff infiltrated reduces flooding and recharges groundwater to ultimately reach the Minnesota River clean and cool.  In addition the bioswale and raingardens beautify City neighborhoods and provide habitat for pollinators and other wildlife.  This project was made possible by funds from the Clean Water Land and Legacy Amendment and local matching funds.

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