Hellstrip

In June, Mikl and I attended the annual Plant Select conference, where an award was presented to the project designers, supervisors Julie Lehman and Holly Shields of Denver City Parks for their very successful seeded native wildflower meadow on the Josephine Street side of Congress Park and along 8th Avenue where it borders the park. When the conference was over, we headed over there to check it out. We were impressed! In June the parking strips were vibrant with flowers and pollinators, The garden had been seeded two years before and was lush and full, with grasses, flowering annuals, perennials and biennials filled in and blooming profusely.

The project was conceived as a demonstration garden that could inspire Denverites to replace lawns with low-water native pollinator habitat that would require very little maintenance. I met yesterday with Julie and Holly for a tour and to gain an understanding of the process that created such a successful result. I found the meadow plantings more subdued in color than they were in summer, but just as rich in fullness, texture and detail.

Both Julie and Holly were already familiar with our native wildflowers, but hadn’t attempted a project like this before. After researching plant characteristics and seed availability, the project designers selected 32 local and regional native species that they thought could thrive together in with the same sun exposure, soil conditions, and watering regime, and not grow too tall for street-side planting. The seeds of many native plants have evolved to require a period of cold conditions to break the dormancy of their seeds, so their selections also had in common the need for their seeds to be cold-stratified for a similar length of time. See their seed list here. Julie points out that ‘So much of this is what you would do with regular seeding of a lawn, same irrigation, same protocols. You could make a seed mix that doesn’t need cold strat, and add the plants that do need stratification by buying them at local nurseries and ‘plugging’ them in.” And Harlequin’s Gardens suggests that you can start your seeded meadow by direct-seeding in the fall and allowing cold winter temperatures do the cold-stratification for you.

The project began with killing the bluegrass turf in the project areas. They chose to use two applications of glyphosate, a product that we at Harlequin’s Gardens cannot promote because of its toxicity to humans, wildlife and soil life.  Instead, we recommend several non-toxic options, including mechanical sod-stripping, solarizing, and sheet mulching.

Next, a sod-cutter was used to cut out the dead turf and roots to a depth of 3”, leaving a level-bottomed “trench”, which was then filled with a gravel mixture of 75% ‘crusher fines’ and 25% gray ‘rock chips’.

In the meantime, the seeds were all mixed together with vermiculite and cold-stratified in the city’s refrigerated facilities. When they were ready in June, a seed-spreader was used to sow them into the gravel, making multiple passes with light applications to distribute the seed as evenly as possible. This was followed by raking the seeds in with a metal fan-rake so they would all fall beneath the surface. The seedbeds were watered thoroughly, and watering continued daily until there were a good number of seedlings showing up, which took one and a half to two weeks. A crew of trained volunteers or interns regularly pulled out weed seedlings as the plants developed.

With an automatic pop-up irrigation system already installed, the meadow areas were, and still are, watered once every two weeks through the growing season.

Another of the project’s goals was to make this approach work for busy gardeners with little time for maintenance. All seeds are allowed to drop, and the gardens are mowed once in December, with the cut materials left on the garden surface (we at Harlequin’s Gardens would recommend leaving the stalks standing until March or early April so that beneficial insects and their eggs are not disturbed). Ongoing maintenance includes weeding regularly.

Kudos to Julie Lehman and Holly Shields and City of Denver Parks! We hope you’ll go and see these gardens, hopefully in more than one season. They provide an excellent model for a way to garden for saving water, money, time and effort, creating beauty, and creating pollinator and habitat. You can easily add new plants into this kind of garden by planting compatible nursery-grown specimens into the meadow.