Master Rain Gardener Homework #1

June 26, 2019

I am considering installing two rain gardens on my property.

The first potential site is located on the north side of my home and is shown in the first two images below. This rain garden would be designed to collect surface water that runs downhill from my neighbor to the north. I would also run one downspout (NE corner of my house) into this garden, which would mean it would manage 1/4 of the water that runs off of my roof. In the middle of the first image, you can see a stump from a recently cut tree, which was a sickly spruce that we had to remove. The tree company will be returning to grind the stump, which they have assured me they can do quite deeply. Regardless, I know I will battle some of the remaining root system as I install the rain garden. Also, I will likely be moving the fence that is pictured, which will allow the garden to reach past the existing fence line to the east, and will capture this side yard into the backyard, so that we can access and enjoy the new garden more easily. You can see that there is already a sizeable Redbud tree next to the intended garden site. The site is fairly shady. I know the space is limited, but I am hopeful that I can design a successful rain garden in this site, as I believe that much of the water that creates our wet basement and requires our sump pump to run heavily after rain events enters my home at the NE corner.

The second potential site is behind my garage and is perhaps the lowest point on my property, as the land slopes to the south (in my yard, and seemingly all of the properties on my street). Water seems to flow downhill from one property to the next, until it pools at the last yard on the block, and sometimes even flows over the road. This garden will be designed to manage the water from the two downspouts from my garage roof. Currently this water basically just runs downhill under the fence onto my neighbors property. I am also considering adding a small french drain to keep the walkway on the north side of the garage from getting muddy (from surface run off from the yard), which would also be routed to this garden. The site receives some morning shade (as pictured), but is in full sun for most of the day.

Comments (8)

  • HU-771522342

    The rain garden on the north side of my home will capture water from 1/4 of the roof area, approximately 756 square feet. My percolation test took 2.5 hours to drain. Accordingly, this garden should be approximately 151 square feet in size, given the 20% rule.

  • HU-771522342

    Again, I am focusing on my north side rain garden for now. In the initial design you can see existing plants in green, existing plants that I intend to transplant elsewhere in green with red shading, and the proposed rain garden location in pink with the square foot cells dotted. I plan to use a PVC conveyance from the downspout at the NE corner of the house. You can see that I am pretty tight up against my property line (where I intend to add fencing along the northern border) and the 10-foot minimum distance from the house. I will also have to move the existing fence line on the east side of this area in order to accommodate the garden. While this obviously creates a lot of additional work, it will capture this area into my backyard and allow for much better access and enjoyment of the new garden. The grey shaded area represents an approx. 2 foot wide berm that will serve as the southern border of the rain garden and help capture surface water that flows down from my neighbor's property before it reaches my foundation. In creating a wider raised berm, I'm hoping that this also can serve as a walkway beside the garden. We have extra bluestone from a previous project that I intend to use.

    Plants I am thinking of using include: Yellow Coneflower, New England Aster, Wild Bergamot, Canada Anemone, Swamp Milkweed, Penstemon, Sensitive Fern and Fox Sedge.

  • NHBabs z4b-5a NH

    Have you researched the moisture tolerance of all these plants? For instance, I don’t know of any Penstemon that likes it really wet, though many are fine with ordinary garden moisture and a lot like it fairly dry. You haven’t mentioned the species or cultivar you plan to plant.

    Several of these are thuggish in garden settings. Monarda/bee balm/bergamot, sensitive fern, and Canada anemone will all spread enthusiastically, overrunning and outcompeting less vigorous plants. Do you have a way to prevent spreading into the neighbor’s yard such as a buried root barrier? I am not sure what you mean by yellow coneflower since there is more than one plant that is given that common name. Do you know the genus and species?

    Do you want any winter interest in this spot? If so, research shrubs that do well in your area in wet spots. For instance, around here, small cultivars of winterberry holly/Ilex verticillata (need a male as well as female) will have bright red berries through the fall and into winter until eaten by birds, red-twigged dogwood has red winter stems and some have attractive berries or nice fall color, or some of the smaller cultivars of Thuja occidentalis get used in damp spots.

    Other small shrubs if you want more structure might include smaller cultivars of Itea virginica/sweetspire or Clethra alnifolia/summersweet, both of which have summer flowers and nice fall color and are quite tolerant of a range of moisture, including quite wet.

    HU-771522342 thanked NHBabs z4b-5a NH
  • Susan Bryan

    Love your plan! Pennstemon difitalis should do fine in a rain garden.

    HU-771522342 thanked Susan Bryan
  • Susan Bryan

    I like that you ultimately chose a spot that you will see more often. Behind the garage you wouldn’t see hardly at all!

  • HU-771522342


    We have moved the fence and I have started to relocate some of the existing perennials. You can see the new space and the planned rain garden outlined in orange flags in the photos below. You can also see my draft planting plan.

    Draft Plant List:

    Sensitive Fern (Onoclea sensibilis)

    Blue Flag Iris (Iris virginica)

    Fox Sedge (Carex stipata)

    Purple Coneflower (Echinacea pupurea)

    New England Aster (Aster novae-angliae)

    Swamp Milkweed (Asclepias incarnata)

    Great Blue Lobelia (Lobelia siphilitica)

    Wild Ginger (Asarum candense)

    Wild Geranium (Geranium maculatum)

    Red twig dogwood (Cornus sericea)

    Any feedback is appreciated before we break ground!

  • HU-771522342

    Sharing a revised plan based on some feedback I received.

    Plant List:

    Blue Flag Iris- Iris virginica

    Fox Sedge- Carex vulpinoidea

    New England Aster- Aster novae-angliae

    Swamp Milkweed- Asclepias incarnata

    Great Blue Lobelia- Lobelia siphilitica

    Wild Ginger- Asarum candense

    Wild Geranium- Geranium maculatum

    Nodding Wild Onion- Allium cernuum

    Red twig dogwood- Cornus sericea

  • NHBabs z4b-5a NH

    IME Asarum canadensis likes moist but well-drained soils. I have never seen it growing in periodically flooded areas. Perhaps grow it on the side of the berm? It also likes shade, while all your other plants like a lot of sun.

    Be aware that many of your plants will be enthusiastic seeders and may spread beyond the rain garden. In my yard great blue lobelia has seeded under shrubs and into the veggie garden just from it having been in the garden for two seasons many years ago before I removed it, so you may want to deadhead some of them.

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