From the Ground Up
by Jeanne McRight
Nurture your soil
Boulevard garden soil can be of poor quality. The fine-textured clay loam soils that prevail in southern Ontario are nutrient-rich but soil aggregates are easily damaged when exposed to foot traffic, toxins, drying heat and wind and other harsh roadside conditions (Fig. 1). Even plant species adapted to survive these challenges will sometimes need a little help if they are to thrive. A soil test will tell you if amendments are needed.
Salt and compaction are common challenges in boulevard gardening. Salt damage happens via winter de-icing on sidewalks and road salt spray. When soil is compacted salt residue is retained, reducing the water that roots can take up and causing drought stress. Also, roots can transport salt to leaves, resulting in tissue death. Plants coming out of dormancy are most susceptible to injury. Adding organic matter reduces compaction by increasing soil porosity, allowing water infiltration that leaches salt away from the root zone (Fig. 3). Aggregate stability, water holding capacity, drainage, nutrient retention, and plant root growth are all increased when organic matter is incorporated.
Once established, herbaceous perennials native to the Lake Erie-Lake Ontario prairie and savannah ecoregions require little or no extra water (Fig. 4). They do require good drainage, so irrigation management should emphasize restraint.
Irrigate plants based on their needs and not on an arbitrary schedule. Spot watering and drip irrigation is an effective solution for established native plant communities if stressed by drought. All new plants will require regular supplemental watering for the first year or two. After they have developed a good root system, supplemental watering needs will be infrequent.