1 © 2011 Regents of the University of Minnesota. All rights reserved. 11 RESIDENTIAL RAIN GARDENS Graphic: City of Maplewood

2 A rain garden is a water-quality tool that you can use in your own yard.

3 © 2011 Regents of the University of Minnesota. All rights reserved. WHAT WE’LL COVER  What is a “rain garden”?  Functions and benefits  How to make one  Plant selection  Maintenance  Cost  Helpful resources

4 WHAT IS A “RAIN GARDEN”?  A shallow sunken garden that recycles the rain –less than 8” deep  Rainwater runoff is directed toward it  Runoff soaks in Photo: Mary Nolte, Fulton neighborhood, Minneapolis

5 © 2011 Regents of the University of Minnesota. All rights reserved. PLANTS HELP RECYCLE THE RAIN  Plant roots absorb water  Water goes up the stem  Leaf surfaces release moisture  Water returns to the atmosphere as a vapor

6 © 2011 Regents of the University of Minnesota. All rights reserved. A RAIN GARDEN IS ALSO KNOWN AS...  Mini wetland  Water quality garden  Stormwater marsh  Planted swale  Bio-retention pond  Strategically placed puddle

7 © 2011 Regents of the University of Minnesota. All rights reserved. FUNCTIONS OF A RAIN GARDEN  Diverts runoff from paved surfaces –Driveways, roofs, streets, patios, walks  Water moves “sideways” – runs off pavement  Keeps runoff on site –Instead of flowing untreated into streams and storm sewers  Soil acts like a living sponge –Water moves “down” - into the ground

8 © 2011 Regents of the University of Minnesota. All rights reserved. BENEFITS OF A RAIN GARDEN  Soaks up 30% more runoff than lawns  Filters polluted runoff sediments, fertilizers, pesticides  Recharges groundwater  Helps prevent flooding  Provides habitat/food for butterflies, birds  Beautifies a low spot in the yard

9 POLLUTED RUNOFF HARMS WATER QUALITY  Flows into waterways untreated  Harms fish and wildlife  Kills vegetation  Fouls drinking water supplies  Makes recreation areas unsafe

10 EVERY CURB IS A SHORELINE Grass clippings and leaves are the main source of phosphorus in lakes and streams Rain gardens act as filters and remove: –94% of sediment –43% of phosphorus –70% of nitrogen

11 © 2011 Regents of the University of Minnesota. All rights reserved. DESIGN FEATURES ARE FLEXIBLE Variables include:  Location  Soil  Size and shape  Plants

12 © 2011 Regents of the University of Minnesota. All rights reserved. © Fitch & Co. LOCATION OF THE RAIN GARDEN

13 © 2011 Regents of the University of Minnesota. All rights reserved. GO WITH THE FLOW  Observe the drainage pattern in your yard  Locate the garden: –in a natural low spot –near sidewalks, driveways, or other paved surfaces –down-slope from roofs, gutters, downspouts, sump pump outlet  Direct water into rain garden –channel or buried plastic pipe

14 Project and photo by Kestrel Design Group

15 Locate the rain garden at least 10 feet from the house, on a gentle slope

16 © 2011 Regents of the University of Minnesota. All rights reserved. BIRD’S-EYE VIEW OF RAIN GARDEN LOCATIONS Graphic: UW Extension Service

17 © 2011 Regents of the University of Minnesota. All rights reserved. TRADITIONAL PATH OF ROOF RUNOFF Graphic: Applied Ecological Services, Inc.

18 Average runoff from a roof is 24,000 gallons per year That would fill 600 bathtubs!

19 © 2011 Regents of the University of Minnesota. All rights reserved. ROOF RUNOFF DIRECTED TO RAIN GARDEN

20 © 2011 Regents of the University of Minnesota. All rights reserved. RAIN GARDENS IN HOME LANDSCAPES In a back yard catching runoff from the garage In a front yard catching runoff from a downspout

21 © 2011 Regents of the University of Minnesota. All rights reserved. THE SOIL MUST DRAIN!  A rain garden is NOT a pond.  Percolation test: –fill a 6-inch-deep hole with water –should drain within 24 hours –if not, don’t put a rain garden there –or amend soil  “Rain garden soil mix” –50-60% sand, 20-30% topsoil, 20-30a% compost

22 © 2011 Regents of the University of Minnesota. All rights reserved. HOW BIG?  No standard size  Rule of thumb: 1/3 of drainage area –e.g., 170 sq. ft. (10’ x 17’) garden for 500 sq. ft. of drainage area  Factors include slope, soil type, distance from runoff point  Even a small rain garden is beneficial

23 © 2011 Regents of the University of Minnesota. All rights reserved. CALCULATING DRAINAGE AREA Area of roof going to down spout  Length of house 100 feet  Width of house 20 feet  L X W = 2000 sq ft  2000 sq ft ÷ 4 = 500 sq ft draining to the rain garden Width LengthLength Graphic: UW Extension Service

24 © 2011 Regents of the University of Minnesota. All rights reserved. DESIGNING THE RAIN GARDEN  Call Gopher State One:  Outline it with rope or hose  curvy shape  Remove sod and dig to desired depth

25 © 2011 Regents of the University of Minnesota. All rights reserved. DESIGNING THE RAIN GARDEN Features :  gently sloping sides  flat in the deepest spot  berm at low end  grass filter strip on top edge  mulch – shredded bark

26 © 2011 Regents of the University of Minnesota. All rights reserved. A soil berm acts like a bumper – keeps water from flowing over edge Photo: UW Extension Publication GWQ037 Berm

27 RAIN GARDEN COLLECTS PARKING LOT RUNOFF Photos & design: Kestrel Design Group Spray paint outlines the garden shape

28 Parking lot runoff flows into the rain garden instead of into the street Runoff pools in the garden, then seeps into the ground Photo and Project by Kestrel Design Group

29 Graphic: UW Extension Publication GWQ037 BIRD’S-EYE VIEW OF A RAIN GARDEN

30 © 2011 Regents of the University of Minnesota. All rights reserved. LAYOUT FOR A 140-SQ.FT. GARDEN Graphic: UW Extension Publication GWQ037

31 Photos: Mary Nolte Before After Buried pipe connects to downspout Berm

32 © 2011 Regents of the University of Minnesota. All rights reserved. PLANTS FOR RAIN GARDENS

33 © 2011 Regents of the University of Minnesota. All rights reserved. SELECT PERENNIAL PLANTS THAT  Tolerate both wet and dry spells –plants that like wet feet in deepest part  e.g.: Blue flag iris, marsh milkweed, big bluestem, sedges, red-twigged dogwood, buttonbush  Tolerate de-icing salts (if near roads)  Match up with soil and light conditions

34 NATIVE PLANTS HAVE ADVANTAGES  Adapted to the climate and native pests  Deep rooted –long roots make channels in the soil for water to follow  Havens for butterflies, birds, beneficials

35 © 2011 Regents of the University of Minnesota. All rights reserved. PRAIRIE PLANTS HAVE DEEP ROOTS Graphic: Conservation Design Forum Inc.

36 © 2011 Regents of the University of Minnesota. All rights reserved. RAIN GARDENS IN MAPLEWOOD, MN INSTEAD OF CURBS AND GUTTERS Photo: City of Maplewood

37 © 2011 Regents of the University of Minnesota. All rights reserved. SUN GARDENS Photos: City of Maplewood

38 © 2011 Regents of the University of Minnesota. All rights reserved. GARDEN FOR LIGHT SHADE Photo: City of Maplewood

39 © 2011 Regents of the University of Minnesota. All rights reserved. Shrubs:  Annabelle Hydrangea  American Highbush Cranberry  Anthony Waterer Spirea Perennials:  Marsh Milkweed  Stello d’Oro Daylily AN EASY SHRUB GARDEN Photo: City of Maplewood

40 © 2011 Regents of the University of Minnesota. All rights reserved. MAINTENANCE  Pull weeds (esp. the 1 st year)  Water ~3 x a week until established –also during a dry spells  Mulch –shredded hardwood won’t float away  Cut back or mow down

41 © 2011 Regents of the University of Minnesota. All rights reserved. WHAT ABOUT MOSQUITOES?  A rain garden is not a pond  No standing water between rainfalls  Mosquitoes need at least 7 days in standing water to hatch –will not survive if wetland dries out in less than a week

42 © 2011 Regents of the University of Minnesota. All rights reserved. ESTIMATED COST AND PLANTS NEEDED  Do-it-yourselfers: –about $3 to $5/sq. ft.  Professionals: –about $10 - $12/sq.ft  Plants needed for 300 sq. ft. garden –100 for wet zones –200 for upland zones

43 © 2011 Regents of the University of Minnesota. All rights reserved.  Shallow saucer shape  Strategic location  Plants match soil and moisture levels  Soil drains  Size appropriate for yard and drainage area SUMMARY Photo: Mary Nolte

44 © 2011 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer. In accordance with the Americans with Disabilities Act, this PowerPoint is available in alternative formats upon request. Direct requests to the Extension Store at Discover more at extension.umn.edu