Hillside Planting (Retaining Wall Alternative)

This house is located on the corner of a city block in Saint Paul. The homeowners had to remove the original retaining wall because it was falling apart. The homeowners found that the cost to rebuild the retaining walls would have been very expensive. Instead they decided to use native plantings to stabilize the hillside on two-sides of their lot. The west side is partially to mostly shaded from street trees. The south side (the long side) is half partially shaded all day and the other half is in full sun for most of the day. To compound the challenge, the soils are sandy fill soils with some compost material. This is how I met the challenge.

I used Minnesota native woodland plants in the shaded areas and native prairie plant species in the sun. The planted areas in the shade didn't fill in nicely until last year (5 years after original planting). The sandy soils slowed down the root establishment of the plants. The homeowners even used drip-irrigation to help sustain the plants during a longer than usual establishment time. New plants usually root into soils well after 2 or 3 growing seasons.

In stark comparison, the native prairie plants adapted very well to the sandy soils within 2 growing seasons. Some Prairie Dropseed Grass (Sporobolus heterolepis) was added to ensure that there was good coverage of the ground. Roots of prairie grasses run 4ft. -5ft. deep or more.


Over the years, I have showed this hillside to people for ideas regarding hillsides in small city lots. People who love native plant gardening/landscaping like how this garden hillside evolved over time. People who are still hesitant about using native plants (because they still cling to the formal landscaping ways) often remark that "they like certain parts of the planting" while "other parts look neglected or messy".

I don't mind hearing these kinds of comments. These comments help me evolve as a landscape designer. I strive to understand native plants and native plant communities to improve how to blend the "natural" and the"built" realms.