A guide to tucking in your rain garden for winter

November 4, 2015
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A few simple steps will keep your rain garden healthy when the weather gets cold – and reduce hassles when the weather gets warm.

Yes, it’s that time of year. Time to tuck in the rain garden for the winter.

“October and November are great times to get the garden ready for winter,” said Ann English, coordinator of the Montgomery County Department of Environmental Protection RainScapes Program. “It’s not too cold, but things are slowing down.”


Woman weeding a rain garden

Nice weather and slower growth make October and November a great time to prep your garden for winter.


As with all aspects of rain garden maintenance, winter prep is similar to the prep one might undertake for any garden, just with a few tweaks. Clearing weeds and checking mulch now can reduce maintenance when spring springs again.

Courtesy of English and the rest of the Rainscapes team, here’s a handy checklist:

  • Don’t wait until the snow has come and gone to remove those summer weeds. “Summer weeds drop seeds and are worse next year,” English said. So be sure that weeding is a part of your planning.
  • Keep pruning to a minimum. This may be one of the most common misconceptions when it comes to autumn gardening. While best practices can differ from species to species, in general less is more when it comes to trimming back in the fall. Delicate new growth is extra vulnerable to cold temperatures and can expose a plant to serious damage or even death. What’s more, pruning promotes new plant growth at a time when a plant’s biological clock is telling it to hibernate.


rain garden in summer


  • Check your mulch depth and ponding depth in the rain garden. Mulch should be 3” deep and ponding depth should be 6” deep for a rain garden and 3” deep for a conservation landscape. For more information on how to calculate ponding depth, click here.
  • Divide blooming perennials as needed. Fall is an ideal time to divide these plants because all of a plant’s energy can go toward root and leaf growth, as opposed to flowers. Prune back these perennials, remove the parent plant with a spade or shovel and dig the plant four to six inches away from the plant. Then pry out the plant, separate evenly by its root systems, and carefully replant the divided plants. If you have extras, share with friends or plant in other areas of your garden.
  • Non-blooming perennials such as warm season grasses like switch grass, muhly grass, and little blue stem—all common rain garden additions—should be left alone in autumn, as they are best divided in the spring.


Fall grasses in a rain garden

Switch grass (right) makes a great addition to any rain garden!


  • If your perennials and shrubs do not need dividing, leave them alone.
  • Check for erosion or berm settling and repair as needed. You can identify erosion when soil is deposited near sloping areas in the rain garden, or the soil contains channels or has a “drifted” look. Erosion can be prevented or remediated by spreading new mulch over the eroded area.
  • Thoroughly rake away fallen leaves. This helps preserve the garden’s ponding capabilities.
  • Each month during autumn, check for cool-season weeds. Gill-over-the-ground and chickweed are two of the more prevalent cool-seasons weeds in our area.

For more information on rain garden maintenance in general, check out our fact sheet here.


By Scott Harris, Freelance Writer. Read Scott’s other posts on the benefits of environmental peer pressurebirds and climate change, eco-friendly ice rinks, residential solar, and congregational rain gardens.



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