Rainscaping Guide: Design & Build a Rain Garden

Now that you have determined that a rain garden is right for your site, you are ready to design and build one! These steps will guide you through the process (click on each topic in the flowchart below to view that section):

Flowchart

Design and Build a Rain Garden flowchartPlant the Rain Garden

Lay out the plants according to the design. This is the time to double-check spacing, arrangement and any other considerations such as texture, height and bloom time.

When planting, gently remove the plant from its container and loosen the roots if they are root-bound.

If the planting is in erosion blanket, cut an ×-shaped hole in the netting large enough to adequately set the plant in the soil beneath.

Each planting hole should be dug approximately twice as wide as the root mass and deep enough to allow for the crown (junction of roots and green shoots) to be set at ground level. Firm the soil both in the planting hole and around the plant after planting. Do not leave root ball/potting soil exposed to air.

Applying 2–3″ of shredded hardwood bark mulch to your rain garden will help lessen the compaction of the soil thereby improving the functioning of your rain garden. When mulching, apply a 2–3″ thick layer around the plants, but not on top of the crowns. This will help keep moisture around the root zone as the plants become established.

Note: In rain gardens and bioswales with high volume, high velocity water and/or steep slopes, organic mulches such as shredded bark are not recommended since they easily wash away and expose the soil to erosion. Instead, use stone and gravel in areas with high energy water such as these.

Use of name labels on plants will help with identification and tracking which plants are doing well. You may want to add them for general knowledge and understanding of the garden also.


Hibiscus lasiocarpos
Rose mallow (Hibiscus lasiocarpos)
Provide Water for Establishing Plants
As with any new planting in the landscape, the plant establishment phase is the most important. Supply water to reduce transplant shock and to assure moisture is available while the plants’ roots and crowns are growing, especially when using smaller transplants such as plugs (smaller than 1-quart-size plants). The general rule of thumb is to supply approximately 1 inch of water per week (including rainfall). The first month is the most critical and watering may need to be done every 2–3 days in the first couple of weeks depending on the weather conditions. The remaining first year is a time to keep a close eye on the progress and growth of the plants to prevent plant loss.

Continue on to Maintain the Rain Garden

 

Link to Is a Rain Garden Right for Your Site? section Link to Determine Rain Garden Size and Depth section Link to Decide Which Rain Garden Elements to Include section Link to Organize Water Flow section Link to Select Plants section Link to Gather Tools and Supplies section Link to Lay It Out and Dig In section Link to Plant the Rain Garden section Link to Maintain the Rain Garden section
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The Missouri Botanical Garden Rainscaping Guide is partially funded by the Mabel Dorn Reeder Foundation and US EPA Region 7 through the Missouri Department of Natural Resources (subgrant number G11-NPS-15), under Section 319 of the Clean Water Act.