Since we opened the Souto sun garden section of JLBG to the public, circa 2014, we’ve been dealing, rather poorly, with an unsightly water runoff capture pit on the east side of the garden. The 30′ x 30′ pit was first filled with weeds, and later converted to a bed for marginal aquatics like cannas and crinums. Over the last few years, cattails had taken over, rendering it somewhat more attractive, but far less diverse.
Three years ago, we made the decision to transform it into a styillized bog garden/rock garden combination. To do so, would require the elimination of the cat tails, which took the better part of two years. Last year, with the cat tails finally eliminated, Patrick, Jeremy, and I strategized what we wanted the bog to look like and how we would make it happen. Armed with everyones’ input, Jeremy took over the construction design and implementation.
Our first step was to remove several truckloads of squishy muck that covered the bottom, since this would not provide the stability we needed to set large rocks.
With the pit finally firm and level, it was time to closely examine water flow from both surface and subsurface water.
Next, the pit was re-filled with our native sandy loam, with a central “gravel burrito”, which would allow subsurface water a way to exit without erupting upward into the planting area.
The next step was the installation of underlayment and the pond liner. Despite the site being already waterlogged due to a high water table in the area, we felt that the use of a liner would give us more precise control over the water level.
To keep the liner from floating while we worked, we began refilling the bog with our new soil mix of 50% native sandy loam and 50% peat moss. Around the edges, where the rock garden would be installed, we used a base of concrete blocks to support the weight of the rocks. These were located on the outside of the liner, so the blocks would not leach chemicals into the acidic, nutrient deficient bog.
In the center of the bog, we used double-wall drain pipe, stood on end to support the centerpiece of huge boulders.
The large rock feature was then installed on top of the support pipes, along with an ancient stump which Jeremy unearthed on the property.
Rocks with planting pockets were then installed along the edge on top of the cinder block wall. .
The final step was the installation of entrance steps into the bog and pathway stones, which will allow visitor a closeup view of the plants. Initial plants are in the ground, but more will be added as they are ready. The crevices planting mix (same as the bog) has a pH of around 4.0, compared to all our other crevice gardens on the property, which have a pH around 8.0. This should allow us to grow an entirely new array of plants.
From start to finish, the entire project took Jeremy, Nathan, and some occasional help from other staff, 3 1/2 weeks…job well done!
We hope you’ll drop by during our spring open house and check out the new Rock Bog in person.