Rain Gardens

Learn about how to manage precipitation run-off and add to the aesthetic environment by building a suburban rain garden.
Rain Gardens - Videos

Instructors

Consumer Horticulture; Master Gardener Coordinator Plants for pollinators Native plants & Ecological landscaping

More by Constance Schmotzer 

Integrated Pest Management Entomology Horticulture

More by Tim Abbey 

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- [Tim] Hi, I'm Tim Abbey.

I'm a commercial horticulture educator with PennState Extension.

I would like to spend the next few minutes with you talking about growing a suburban rain garden.

We will use this landscape as our model.

Here you can see it at the beginning.

In this case, the homeowner's goal was to manage storm water on the property while creating a beautiful garden.

A rain garden serves many purposes but the main one is to manage precipitation runoff.

A rain garden, particularly one utilizing native plants, provides food and shelter to numerous animals, insects, birds, mammals, reptiles, and amphibians.

Finally, the most noticeable reason to have a rain garden is the aesthetic appearance of the garden in the landscape throughout the year.

You cannot just buy a few plants and plant them in the ground, expect success.

There are many items to consider, including plant species, their placement, and future maintenance of the rain garden.

In order to have a successful and attractive rain garden, there are important preliminary steps that need to be taken.

First, send a soil sample off for a soil test.

You need to know the soil pH, the level of nutrients, and the percent organic matter.

Plants have specific growing requirements.

They will not thrive if put in the wrong soil conditions.

The same goes for sun exposure.

Some plants require full sun.

Others do better in shade.

Slope analysis identifies areas that will dry faster and where soil moisture will persist.

Knowing where precipitation flows helps to guide placement of plant species that perform best with water.

Hardscapes include patios, stones, walls or water features and should be installed first.

There are numerous resources for finding information on specific plants.

Native plant species should be used whenever possible as they will able provide the most benefit to wildlife.

After you've selected the appropriate species, a decision has to be made on the size to install.

Many species can be purchased as plugs or as plants.

There are pros and cons to each size.

When going with larger plants, the pros include easier to visualize the design, can fill smaller gardens.

You see what you are getting, meaning there's growth above and below the container.

And plants fill more quickly.

Cons include prices higher per plant.

The planting might take longer because you have to dig larger holes.

They may require more frequent watering and using more water each time as you try to establish the plants.

If you use plugs, pros include great for use in larger projects because you can buy them in larger quantities.

Packs are designed to reduce root circling so plants arrive with deeper water root systems.

Price per plant is lower.

Plugs adapt quickly to on-site soil conditions, easier to plant because you're digging smaller holes.

Plugs do start out smaller but can catch up very quickly with their growth and it's easier for wholesale growers to ship if you're buying larger quantities.

Some cons if you use plugs.

Plugs are usually sold by wholesale nurseries in full trays, meaning one plant type per tray, so you don't usually get a mix.

For an average size project, buying in packs may not allow for enough plant diversity.

And planning time to maturity is slightly longer than if you went with larger plants at the beginning.

The actual design should be done simultaneously while selecting the desired plant species.

If the proper plans for the growing site are not selected, then the overall plan falls apart.

For a large garden, develop a master plan.

This is also good if you're going to do it as a small one too.

Place the hardscapes and other architectural objects first.

This allows for the appropriate plant placement around these permanent structures.

Here we see the landscape with the hardscape components in place.

After the area's been cleared of unwanted vegetation and any soil grading has been done, it is useful to spend some time observing the area.

Evaluate the site for wind, sun movement, and water flow.

This gives you a feel for what the garden will look like throughout the day and under different environmental conditions.

Also, observe where to place the plants.

Move the containers around so that you can actually see them where you may plant them.

Place them in the appropriate areas you observe, wet areas, full sun, heavy shade.

This is an aerial view of the rain garden showing the initial plug planting.

Humans have a tendency design in blocks, blocks of color or plant species or geometric shapes.

Nature designs through movement.

Seeds are moved by wind, water, and animals.

You may have done everything according to your research plan, however, remember that nature isn't going to follow your plan.

Some native plants are more aggressive spreaders and will move their population.

Also, remember nature abhors a vacuum.

If there is space, plants will fill it.

It could be desirable plants or ones considered weed species.

One of the main reasons rain gardens fail is that people do not develop a maintenance plan.

Undesired species can ruin the function and aesthetics of any rain garden, particularly in the early stages of establishment.

Let's look at the first section of the rain garden installation.

In our example, plugs were used at the time of planting.

Here is that section of the plan one month after planting.

This is the second section of the design plan that was installed below the walk bridge, or, in other words, downstream from the upper garden closer to the house.

This is a visual looking down from the bridge.

Let's watch the process unfold.

Here's the site at the beginning.

Turfgrass was growing up to the foundation of the house.

The area was heavily shaded by evergreen trees.

Storm water from two neighboring homes drained down from the slope at the far left of the picture.

This water, along with water draining off of the roof, caused water issues in the basement.

This is a picture looking down into the yard from the slope above.

An early stage of the redesign showing the installation of some of the hardscape, specifically the bridge and two decorative stones.

A picture from the second floor of the home showing the lower section of the garden in December of the year of planting.

A view of the completed garden one year after planting.

The new hardscape is in place and the herbaceous plugs have started to grow.

A different view of the top of the garden during the summer of year one.

The lower garden with the walking bridge.

Note how the plugs have begun to fill in the space.

An aerial view of the lower garden two years after installation.

The walking bridge area two years after installation.

The patio area two years after installation.

In summary, a rain garden can add so much to a landscape, striking visual interest, wildlife food and shelter, and a water filtration system.

Please consider making part of your landscape a functioning beneficial ecosystem.

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