The plants in the rain garden at Behnke Nurseries have now been growing for about 13 months, and they are doing quite well. We planted the garden because we were approached by the Low Impact Development Center, Inc., Beltsville, which was administering a grant from the Chesapeake Bay Trust. They were looking for a place in Prince George’s County where examples of the seven projects that can earn a rebate from Prince George’s County Raincheck Rebate Program could be installed. (For more about the program overall, see “Getting Paid to Save the Bay.”) Please stop by to look at the rain garden, cistern, permeable pavers, etc: you can get a location map showing the seven examples at the Information Counter when you first enter the building from the Behnke’s parking lot. You can also get maps of the rain garden and pollinator garden.
We do indeed have a big asphalt parking lot at Behnke’s, and we were looking for a way to capture some of the runoff through a rain garden. The garden was built by Stormwater Maintenance and Consulting; Behnke’s selected the plants and planted and maintain the garden. As a homeowner, you may use a contractor, or you can go totally DIY like Behnke employee Deb Sheppard and her husband Dave. Either way, the site must be inspected in advance, your plan approved, and the work inspected upon completion for you to get a rebate. You will receive $10 per square foot of the garden as a rebate, minimum 100 square feet.
A homeowner may receive a maximum of $4,000; for a business, homeowner’s association and other larger scale projects up to $20,000. This is across all possible projects of the seven rebate-earning storm water projects, so if you planted trees, put in a cistern, and did a rain garden, the maximum would still be $4,000. (Some projects, like installing a rain barrel, do not require the various inspections.)
A commercial installation for a business is complicated, and will likely involve a design/build firm like Stormwater Maintenance. The garden must be sited in the proper place and the subsoil must drain (or “perc”). The garden is then excavated, and filled with a series of filtering and draining layers, with big rocks at the bottom, then smaller rocks and ultimately a well-draining soil mix on the top, leaving a shallow trench for planting and collecting the water. Overflow drains are included in case the rain fills the pond to overflowing. The goal is for the garden to drain within 24 hours: we don’t want to be creating a refuge for mosquitoes; it’s not a bog or a holding pond.
Because the soil drains well, the plants chosen must tolerate alternating conditions of drought and flooding. Plants for our garden were chosen from a list of acceptable native plants provided to us. I selected the plants based on various horticultural criteria, mainly good looks and availability. (The same criteria Mrs. Hurley used when she selected me. Never argue with what works.)
We have had to water during dry spells (especially after the initial planting) because of the second word, rain “GARDEN.” Gardens require some maintenance to look good. It’s always frustrating to see a native plant garden of any sort descend into the hell of becoming just a giant weed patch. We have chosen to allow the plants to reseed, so that overtime the garden will fill in and out-compete most weeds. We mulched last year with hardwood mulch while the plants were rooting out. Over time, much of it has decayed, while the larger pieces have been deposited up on the dry end of the bed, like so much jetsam. We didn’t find it necessary to apply mulch this year.
Weeds have not been a problem on the upper (drier) end of the garden, but have thrived on the lower end. Since somehow this is “Larry’s Garden” I have done the weeding, all by hand (no herbicides). There hasn’t been that much necessary. Because of the sandy base soil of this installation, they come out easily, and I’m not that fussy about this planting, focusing on the low-hanging fruit so to speak, or the big weeds. Planted ornamentals New York Ironweed (Vernonia) and the Perennial Sunflowers (Helianthus) both generated seedlings this spring, most of which have survived my nimble fingers. Not unexpectedly, a couple of poison ivy plants have popped up and been removed. You must always be careful of the three-leafletted menace.
For their homemade garden mentioned above, Deb and Dave used a different soil mix that was much more organic than our sandy mix, and it is working fine for them. Their experience with the installation is documented on Youtube.
Dave is pretty handy, and between the two of them, they were able to do the entire installation themselves at essentially no cost (after the rebate) except their own labor hours. Planted around the same time as the Behnke garden, the Sheppard garden has solved many of the drainage problems around their home, reduced overall runoff, and yielded an attractive addition to their landscape. Plus, Dave got to drive some really cool equipment, which you too could rent. Vroooommm!!!
- Chesapeake Bay Trust, with helpful links.
- This site gives numerous designs for rain gardens, with plant lists.
by Larry Hurley, Behnke horticulturist
This is a followup to the article: “A Little Rain Must Fall,” from May 25, 2016