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You already have the location
and size of your rain garden
so now you are can start installation.
First you need to delineate the actual border
to begin installation.
Use strings, spray paint, or a hose
to draw the outline of your rain garden.
And play with the shape
until you like the layout
within your existing landscaping.
Then you will need to remove the grass.
You can use a shovel, sod cutter
or you can kill the grass ahead of time
by laying black plastic or a tarp
where the rain garden will go.
This method may take a couple of weeks
so pre-planning is needed.
Using herbicide may negatively affect
the new plants you are planting.
So this is not a recommended method
of grass removal.
Before digging, call Indiana 811
to have underground utilities marked.
It generally takes 2 full working days
to have utilities marked
so please think ahead.
If you discover the utilities are within your selected location
you may need to reconsider the site location.
Begin digging your rain garden.
For small gardens,
digging can be accomplished by hands using shovels.
For larger gardens,
it is more efficient to use large equipment
to remove the soil.
As you are digging
you should begin shaping your rain garden.
The goal is for a wide
flat bottomed area in the middle
with gently sloping sides
Blue Thumb recommends the sides slop 3 to 1 or flatter.
Using the example in the book
if you rain garden depth is 6 inches
the side slope should be 18 inches.
You determine the depth of the rain garden
when you calculated the infiltration rate.
Check the depth frequently by using a long board
that extends across the rain garden
and measure from the soil level
to the bottom of the board
Once you have your desired depth
dig the rain garden bed 4 to 6 inches deeper
so that you can add compost.
Set the soil aside.
You will use this soil later
if your soil test indicated good infiltration.
If not you will need to add an amended soil instead.
And this soil will need to be used
elsewhere on the property
or transported away for another use.
Landscaping companies can provide amended soil
that they mix for you.
In some cases to ensure the best filtration
rock is added as a base material.
Here you can see that rock was added
to a depth of 5 inches.
then over layed with geotextile fabric
to keep sediment out of the spaces between the rocks.
This helps keep the infiltration rate
from declining over time.
If you have a rototiller
till the garden bed to loosen the soil.
You can also use a shovel or pitchfork.
Add about an inch of compost
plus a bit of the soil you removed
or the amended soil if that is what you are using.
Then rototill again working the organics into the soil.
Repeat this process a couple of times
in order to work 2 to 3 inches of compost into the garden.
Then rake and grade your garden.
If your rain garden is on a slope
you will need to build a berm out of dirt,
landscaping stone, or edging
on the down hill side
to ensure the water is held in the rain garden.
Use stakes and string to make the garden level
and help to determine the height of the berm.
Look at your garden
and make sure you understand
where water will be coming in and exiting
and ensure the water will flow
in the way you want it to.
Ensure that when rain garden overflows
during a large storm
that it does not overflow
into your neighbors yard.
It is recommended to use landscaping rocks
at the inlet and outlet to prevent erosion in these areas.
At this point
you may want to make sure the infiltration rate
is correct before planting.
Take a hose and fill your rain garden.
Check periodically to ensure that the rain garden
drains within a day.
If not rework the soil
adding additional organic matter
until the infiltration rate is within 1 day.
Once the filtration rate is correct
plant before the soil dries out
to provide a moist environment for the young roots.
During planting it is important to
minimize the amount of walking done
through the garden to avoid compacting the soil.
One option to minimize compaction
is to place the mulch down before planting.
Unfortunately you will likely end up with
soil on top of your mulch
due to planting if using this method.
To plant
stretch a measuring tape through the middle
of your rain garden along the longest length.
Use the measuring tape to plant
1 plant per square foot
Set plants out in a grid that matches your design plan.
Dig a small hole deep enough
so that the base of the stem of your plant
is a little above the ground surface.
Remove the plant from the pot
and gently loosen the root ball with your fingers.
Set the plant in the hole
and back fill to minimize air spaces around the roots.
Once all the plants are planted
water the entire rain garden.
If you have not already mulched
apply a 3 inch layer of mulch
to keep the plants cool and moist
and to help discourage weed growth.
Leave about 1 inch of space around the plant stem
to prevent stems from being scratched
due to blowing wind.
The Blue Thumb guide recommends
course double shredded hardwood mulch
because the course pieces lock together
and do not float away.
Lighter mulches like pine bark nuggets
or cedar chips will float away
when the garden fills with water.
Also hardwood lasts longer
and needs to be replaced less often.
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