Rain garden

Rain Gardens provide you with more than beautiful landscaping. If you have experienced flooding on your property, this could be one tool to help reduce the risk of it happening again. A rain garden helps to drain the water away from your home during a storm. Follow these steps to learn more about building a rain garden in your yard.

Before you start: Identify location of buried utilities

Make an online request for Utility Safety Partners to mark utility line locations or call 1-800-242-3447.

Flag or paint the location of buried irrigation lines, if necessary.

Materials required: Rain Garden Design, string, stakes, level, metre stick, measuring tape, lawn paint (optional), garden hose

Review your Rain Garden Design provided through the Rain Garden in a Box program.
Measure points along rain garden from side and front property line and mark points with lawn paint or stakes.
Connect points with paint or lay garden hose along garden outline.

Use this opportunity to make any small changes to the rain garden shape. Keep in mind that major changes in location or shape of the rain garden may impact the planting plan and the function of the rain garden.

Materials required: edging spade, rototiller, shovels, wheel barrow, tarp, string, stakes, level, metre stick, sod cutter (optional)

Using an edging spade, cut sod along outline of rain garden border that you have already painted or laid out with string or a garden hose.
- Optional: use sod cutter to cut, roll and remove sod from rain garden area, beginning along outside edge and moving in toward the centre in a circular pattern.
Use roto-tiller to break up sod (if not removed with sod cutter) and existing soil, within the interior of your rain garden layout.
Use shovels and wheelbarrows to remove tilled soil. Continue until depth of raingarden is reached, as indicated on Rain Garden Design. Refer to Rain Garden in a Box Handbook for measuring required depth of garden.
- Optional: Soil can be temporarily placed on a nearby tarp if a trailer/truck is not yet available.
Gently slope edges of soil up from base of rain garden to meet existing ground level. The rain garden should resemble a shallow bowl; the edges should be gradual, not steep.
Ensure base of rain garden is flat, using string and a level, stretched across the garden in several places.
Use roto-tiller to loosen soil (scarify) in base of rain garden to depth of 300mm (12in).
If Rain Garden Design requires, berm the lower edge of the garden with soil removed when digging out the rain garden.
Dispose of sod and excess soil at Edmonton Waste Management Centre (EWMC).

Materials required: shovel, erosion control blanket and seed (optional), sod (optional), washed rocks (optional)

Create an outlet at the sidewalk side of the garden by digging a shallow channel in the berm, allowing water to overflow in the intended location indicated on the Rain Garden Design.
Use string, level and stakes to check that outlet is the lowest point along outside edge of the garden.
Reinforce the outlet to prevent erosion, using rocks, sod or seed and erosion blanket, as per the Rain Garden Design.
If using rock, spread washed rock in a 150mm (6in) layer

The rain garden outlet requires erosion protection since excess water leaving the garden will be concentrated at this location. Rocks or grass on the side of the berm meeting the existing lawn will slow the flow of water leaving the rain garden and protect the soil from eroding.

Materials required: topsoil, shovel, tamper, landscape rake, string, level, 8ft 2x4 (optional)

Fill rain garden with topsoil to depth of 200mm (8in).
Tamp down the soil by walking on it or dropping tamper on the soil surface from a height of 150-300mm (6-12in). Before each lift of soil is installed, soil should be compacted enough that deep footprints are not created.
Install another 50mm to 200mm of soil (depending on depth of garden) and tamp down.
Install final lift of 50mm if garden is 450mm deep, and tamp down.
Rake topsoil to create an even surface with a 2% slope. Check that the surface does not have low areas by using a level and string, or run a 2x4 level across the surface.

Sections of the garden that are lower than the surrounding area, due to compacting soil over time, will tend to pond water during large rain events and can be remedied by filling the area to level with soil, beneath the mulch.

Materials required: shovel, landscape rake, mulch

Scoop mulch into garden placing it into piles throughout.
Spread the mulch evenly, 100mm (4in) deep, by lightly raking into place.

Mulch helps with water retention and discourages weed growth (U.S. Air Force photo by Charles Haymond/Released).

Materials required: garden spade, watering can, plants, gloves

Place plants throughout garden at locations indicated on
Rain Garden Design.
Use garden spade to dig holes, to the same depth as the pots the plants are in.
Use watering can to flood the bottom of each hole.
Remove plants from pots, break up roots as needed, and install in holes, pressing down lightly to ensure top of plant soil matches rain garden soil.
Once all plants are installed, water garden well.

To avoid having to thin plant material later, space shrubs and plants based on their expected mature size, according to your Rain Garden Design.

Materials required: washed rock, shovel

Place washed rock, 150mm (6in) deep, at inlet to garden from lawn or downspout, covering area indicated on Rain Garden Design. This reinforced inlet is to protect the rain garden from erosion and provide a location where sediment can drop out of the incoming water before entering the rain garden.
Slope rock to direct water into the rain garden.

Placing rocks at the inlet slows the force of the water entering the garden, preventing erosion of the soil. Rocks also allow sediment and debris to drop out of the water before entering the garden in order to protect the garden soil from clogging.

Materials required: washed rock, shovel

Identify downspout(s) to redirect to the rain garden.
Cut downspout, connect extender and direct toward rain garden.
Divert downspout extension around rain garden location until the rain garden has been planted, mulched and has an appropriate inlet.

Downspouts can be disconnected and directed into existing lawn or garden areas until the rain garden is complete. Do not direct downspout extension into unfinished rain garden.

Allow runoff from disconnected downspout to enter rain garden.

Congratulations! This is the final step in changing your front yard garden into a rain garden!

See our rain garden maintenance checklist for directions and tips.