With the change in the weather—it may snow tonight in Denver—I found myself thinking about pollinators and how all of us on the High Plains can do a little something to keep up their numbers by spreading a table for them.
The food on that table? Pollen and nectar from native plants (and some non-natives). When I started making a list of the best plants for pollinators, I thought of rabbitbrush (see below) and Western sage (Artemisia), both of them fall bloomers. Both these plants are perennials and can grow quite large, though rabbitbrush can be cut back to a foot above the ground in the winter to keep it compact.
And if you want to attract hummingbirds, agastache (hummingbird mint or hyssop) is a good bet for feeding them in their end-of-summer migration.
Working backward in terms of bloom time, fernbush will produce flowers from June on and, in the winter, will look more or less evergreen. Common milkweed blooms in early summer and is an essential plant for monarch butterflies (especially the caterpillar).
One of my favorite plants, and one I am sure you have seen blooming in June in the foothills of the Front Range, is Penstemon strictus (Rocky Mountain beardtongue). Native to this area, its tubular blue flowers bloom profusely and attract all manner of insects. Best of all, it’s easy to grow and will spread to some extent, though it is not truly invasive.
These plants are suitable for southwestern or drought-tolerant gardens. If you find that type of garden too austere, you could look for plants adapted to Mediterranean climates, such as cooking sage (Salvia). Vegetable gardeners who are willing to let broccoli go to seed will find that bees love its yellow blooms.
Note: Since I live in an apartment, I am not gardening now, but for 15 years I did work to convert my yard in Broomfield to native plants. I have not grown fernbush or common milkweed, sadly. (I did plant swamp milkweed, but it didn’t do well.) I planted a lead plant (false indigo) along the fence in my yard the year before we moved, and I’m not sure what happened to it. The yard has become overgrown, and I can’t find the lead plant now.