Two very different Haliburton native plant landscapes

Here are two Haliburton native plant landscapes Grounded has installed this past month. One is a dry prairie-style garden on a septic leach bed, the other is a shade garden on a steep slope.

The prairie-style native plant landscape

Our clients had a septic system newly installed and wanted the ground covered with native plants over the septic leach bed and surrounding area. The idea was to create a beautiful landscape that didn’t require much maintenance in the form of mowing. As the leach bed was raised and quite prominent, it was important that it looked good, avoiding weeds and the hard work of keeping grass trimmed.

There are special considerations when planting on septic leach beds. While having vegetation on a leach bed is important to help the septic system function well, it is also important to avoid plants that will damage the system.

As a rule of thumb, it is important to choose plants that don’t have deep roots, that are comfortable with dry conditions, and that don’t form a dense mat of foliage.

Here are two good articles that discuss planting on septic leach beds.

• From Cottage Life, written by a well-known expert: https://cottagelife.com/outdoors/the-natural-garden-the-wild-bunch/ 
• From Michigan State University: https://www.canr.msu.edu/news/could-you-please-tell-me-what-native-plants-i-can-plant-on-the-drain-field 

On top of that, it is important to consider the site conditions. Many leach beds have sunny conditions – this one did. But others might be in part-shade, depending on their orientation and nearby tree canopy.

We wanted to cover the ground quickly, to avoid weed pressure, particularly in the the first year. This was particularly acute do a large population of dandelions on a neighbouring property.

Groundcover layer

Grounded chose the following plants for the groundcover layer.

In addition, we seeded the entire site with an annual flower: Plains Coreopsis (Coreopsis tinctoria). This plant isn’t strictly native to the area, but as it’s an annual, which will fade out in a couple of years, it’s a rule I’m prepared to break for the groundcover benefits it brings.

Vignette layer

For the Vignette layer, we chose plants that would give interest at various times of the year.

A couple of these plants have longer taproots, so they were planted away from the actual leach bed, on the surrounding landscape and the slopes away from the bed.

Because we were planting on a leach bed, there was no structure layer of shrubs. The roots of shrubs go too deep for use on these types of sites.

The design

I divided the site into approximately 10 ft square blocks. Each block had more or less the same plants in it, in an arrangement that suited the growing habits of the plants. Here is what a block looked like: the circles are different species of plants in the vignette layer, the blocks are various groundcover plants.

This garden will take a couple of years to fill out. The first summer will require some watering, depending on the weather, while making sure not to overwater for the sake of the plants and the septic bed.

There will also be some weeding required, depending on the performance of the annual plants sowed.

By year three, the ground should be covered and require very little management.

Update: July 2024

I visited this garden a month after it was installed. It grew like gangbusters. This isn’t typical – each garden is different. The rain and sun mix, together with the clients’ diligent weeding, are getting the garden off to a great start.

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The shade sedge meadow native plant landscape

The second Haliburton native plant landscape was quite different.

In the fall, the client had installed a deck on their cottage, facing the lake. This resulted in new landscaping that they wanted filled with native plants.

The site was north facing and shaded, with medium-moist soil. I visited it several times, including once where I stayed for over an hour during the middle of the day to monitor how the sun fell on it. A clearing in the trees allowed sun to penetrate for about two to three hours per day in midsummer. This qualifies it as a shade garden.

I suggested we create a sedge meadow, with a groundcover of three different sedges and then seasonal interest from herbaceous plants and shrubs in the vignette and structure layers.

Groundcover layer

Sedges (Carex species) have many benefits, one of the main of which is their ability to thrive on shaded or part-shaded sites. This is why we have so many native sedges here in Haliburton County. Another benefit of sedges is that they do most of their growing in the spring and fall, when the soil is cooler. This results in the landscape greening up earlier than, say, a prairie-style garden would.

It would be wrong to say sedges don’t have flowers and seeds. They do! A benefit is that they produce their flowers and seeds in the summer, adding interesting during that season.

In addition to the sedges, we also included two species of violets in the groundcover layer. Violets will add some more traditional flowers to the landscape and will happily self-seed all over.

Vignette layer

Woodland plants generally flower in the spring and fall, when leaf cover is reduced. We tried to find plants that tolerate shade and flower at various times of the year, including the summer, for visual interest. Most of the perennials here were planted in groups of four or six.

Structure layer

One of the main aims of the structure layer is to situate the landscape, to frame it. As well as the cottage, the garden had several large trees that framed the lake, as well as steps that came down one side of it.

For that reason, we added just two shrubs to the landscape, to either soften the transition from forest to clearing or to provide an extra bit of visual interest. As shrubs can go quite large, I didn’t want to add too many and reduce the view of the lake.

The design

The vast majority of the plants were the groundcover sedges. These were planted in a tapestry, alternating between the three species. The idea is to create visual interest rather than a flat monoculture of one species.

The herbaceous perennials were planted in groups of a handful of species, scattered throughout the site.

One of the shrubs was planted near the forest edge to soften the transition. The other was planted a sculptural feature in years to come.