by Sandy Garland
The gardens along Bank Street in Old Ottawa South started as a traffic-calming measure. The three rain gardens on Sunnyside were a pilot project installed and monitored by the city. Almost 10 years later, they are all maintained by Green Dreamers, a volunteer group of local residents who love making their neighbourhood look beautiful.
The GDs have an Adopt-a-Road agreement with the city’s Public Works and Environmental Services Department for the street gardens and a maintenance agreement with its Stormwater Management group for the rain gardens. They also take care of the gardens at the Sunnyside branch of the public library and at the community centre. They have no formal agreements for those, but maintain close communication with the managers of the facilities and obey the general rules for roadside planting.
The garden next to Wall Space Gallery now contains native Downy Yellow Violets, thanks to a generous OOS resident. Culver’s Root and Wild Strawberries are at the other end of this bed. The shrubs in the middle are also native species – Ninebark. The large light green plant is Blue False Indigo, a near-native with flowers that are very attractive to pollinators.
For our tour on Saturday, we invited Lydia Wong, a PhD student at Ottawa U, to help us find and identify bees and other pollinators, and Jennifer Drake, a professor at Carleton and specialist in green infrastructure, to explain how rain gardens work. Jenn is also a member of the GD team.
Like many other WPP garden tours, this was not just a chance to look at pretty flowers, it was also intended to be a chance to talk about a type of garden and gardening practices. Because the city recently changed its rules about planting in the city right of way in front of houses, we gave out our brochure explaining what that means and we looked at what grows next to a street. (See Residential gardening in the City of Ottawa’s right of way for more information.)
What I learned about street gardening
Perennials need patience – first-year plants are small and may not bloom. By the second year, the plants will let you know whether they like their location or want to be moved. Those that have settled in may even have to be thinned. In the OOS street beds, the GDs are increasing the number and diversity of native species and watching to see which are most appropriate.
If you are planting near the sidewalk or street, it’s worth Googling “salt tolerant native plants.” It’s also worth checking the city’s list of “prohibited species” — you might be surprised to find common garden plants like lily-of-the-valley and periwinkle there. Both lists are also available on the “Residential gardening…” page mentioned above.
Soil – the soil in the street beds doesn’t seem to contain much organic matter. The GDs have installed compost bins at the library and community centre; they’re still learning how to manage them so that compost will be available every spring. In the street beds, they encourage volunteers to weed BEFORE unwanted plants go to seed. That way they can be put at the back of the garden or under shrubs – out of sight, but able to compost back into the soil they came from so as not to lose any nutrients. Larger amounts of weeds go into the compost bins.
A log, wood chips and even recycled items from the pottery studio help keep rainwater around these plants. Sunnyside, in front of the community centre.
Water – water retention in a street bed will always be difficult. The beds tend to be higher in the middle, causing water to run to the edges. To prevent that, position plants in “craters” – a bit lower than the surrounding soil so that water stays near the plant and its roots. Wood chip mulch and surface-planted logs will also hold water in the soil where the plants can use it.
The Bank Street beds contain trees, so will always need more water than supplied by rain. But the trees also drop their leaves in fall, adding much-needed organic matter to the soil every year.
Two rain barrels catch rain coming off the Firehall roof, providing water for the herb garden as well as the plants along Sunnyside and Fairbairn.
What I learned about rain gardens
In Ottawa, newer neighbourhoods include stormwater management ponds. Older neighbourhoods like Old Ottawa South do not have those facilities and rain falling on the streets runs directly into the river without any treatment.
The purpose of rain gardens is to slow that movement. This can prevent flooding and is better for the environment. Rain from Sunnyside and several side streets flows into the three rain gardens – at Grosvenor, Leonard, and Roslyn – where some stays in the organic soil, some puddles on the surface, some is absorbed by the plants, some transpires through the plants, and some sinks slowly to the weeping tiles below the gardens and into the stormwater system.
A small rain garden, like one in your backyard, can retain 100% of the rain that makes its way into it. A large street rain garden will retain about 50%. These figures depend on how quickly the rain falls and how often, but according to Jennifer Drake, street rain gardens can divert 50-80% of rain annually.
Each rain garden contains an overflow drain at the lower end, but water soaks into the soil or is held by plants before it reaches it. Wildflowers in the raingardens include Blue Flag Irises, Canada Anemones, Rough-stemmed Goldenrods, a cultivar of New England Asters, Panic Grass, and Common Milkweeds have crept into each as well.
What I learned about bees
Finding sweat bee nests at the Firehall. Photo by Kathleen Fisher.
If a bee is loaded with pollen, it’s a female. Female bees not only lay eggs, they also construct the nursery and provision it with all the food their offspring will need until it becomes an adult and can forage for itself. Males visit flowers to drink nectar.
I asked Lydia where bees would have gone during the heavy downpour of rain we had the day before. She said she has seen bees sheltering in or under flowers, likely males as female bees would more likely take shelter in their nest.
During scorching heat, adult bees will find a microclimate that’s less harsh – shade, under vegetation, away from direct sunlight. Larvae aren’t able to move to a nicer place. We might need to rethink placement of bee houses.
During our garden tour, Lydia found the following pollinators.
A potter wasp, found in the rain garden at Sunnyside and Grosvenor. Lydia caught bees and other pollinators in small containers that she passed around to give us a closer look. All were then released, of course. And, yes, potter wasps make tiny clay pots – to hold their eggs and provisions. Photo by Lydia Wong.
Sunnyside library garden (all on sunflowers)
- Long-horned bees (Melissodes); males and females
- Sweat bees (Halictus, Agapostemon, Lasiologssum)
- I didn’t see bumblebees while I was there, but I think you said you saw some 😉
Sunnyside rain gardens
- Sweat bees (Lasioglossum) on the goldenrod
- Potter wasp (Eumenes species)
Firehall garden
- Sweat bees: Halictus on mint, Agapostemon on Joe Pye, Lasioglossum in the ground!
- Common eastern bumblebee (Bombus impatiens) on Joe Pyeweed and honeysuckle.
The highlight of the day was finding sweat bees (Lasioglossum) flying in and out of underground nests in a newly planted garden at the Firehall. It’s good to know that these are not just pretty gardens, they’re helping pollinators, restoring ecosystems, and recycling resources.