If there is one thing I hear most from gardeners in Denver, it is frustration at the conditions presented by our Steppe ecology. Heavy, clay-based soils dominate this former lakebed at the base of the Rocky Mountains. Late season heavy snow, arid summer heat, hail and early freezes challenge plants, especially ones that have arrived from elsewhere. My plant journey started as a child at an even higher elevation of 9,000 feet, where my father, Peter Leonard demonstrated the mastery of moving water across the large meadows of the Lazy Shamrock Ranch in the Blue River Valley near Kremmling. He built a greenhouse to mitigate the very short growing season and we kept a small garden where we never had to worry about the lettuce bolting. It also instilled a sense of ease when I started cultivating urban gardens at a lower elevation here in Denver.
Fortunately, we have several robust gardening communities who offer guidance and resources on how to best cultivate our unique area. In the neighborhood, the Denver Botanic Gardens offers numerous workshops, lectures and ways to engage community members of all ages with their lovely demonstration gardens along the east side of Cheesman Park. Beyond hosting a network of community gardens, the Denver Urban Gardens (DUG: http://www.dug.org) provides online resources, public workshops, garden kits and plant sales of locally adapted seedlings. If you are a gardener without a plot in which to dig, they can even connect you with a neighborhood community garden! The Front Range Organic Gardeners (FROG: http://www.gardenfrog.org) has been an active club with an organic approach to gardening since 1986. Why choose organic? We are in the midst of an insect-apocalypse, which includes the pollinators that are essential to the functioning of gardens. Reducing our chemical footprint allows space for beneficial insects to thrive.
Sometimes it is hard to tell which plants from big-box stores have been ‘neo-nicked’, or treated with bio-cides as part of the plant structure. These plants are VERY dangerous for pollinators. Local plant sales hosted by DUG and FROG are a wonderful way to source garden-safe plants that have adapted to high country conditions. Another good direction is to plant native! Native plants thrive in our specific ecology. Once established, they are so easy to grow that we often need to start sharing them after they have taken off in our own gardens. The front Range Chapter of Wild Ones (frontrange.wildones.org) and the Colorado Native Plant Society (www.conps.org) tend to be flush with native seeds and plants in their annual plant exchanges, which are free to participate. Bring saved seeds from native plants, or seedlings that have emerged in unwanted places to exchange and diversify your collection. New to natives? Bring your questions and gather seeds to try out in your garden. Both organizations provide ways to engage with plants through hands on workshops and restoration sessions that are led by passionate individuals who carry deep knowledge about our local ecology. Feeling neighborly? Plant exchanges with neighbors is a great way to get to know each other and reinforce the community that has made Congress Park into one of Denver’s best neighborhoods.
By the end of February, seeds from most native flora should be sown in order to benefit from exposure to winter freezes and moisture to help break the hard shells. As spring progresses into March, we sow seeds that need a shorter exposure time to winter’s harsh weather. In April, we move on to seeds will germinate with exposure to light and moisture, without having to freeze.
There are a few ways to sow seeds outdoors. According to the Denver Botanic Gardens, the smaller the plant, the stronger the adaptation to growing in this challenging zone. Direct sowing seeds to the place they are intended to grow allows them a start without needing to adapt to re-planting. If we have an area in our garden that needs filling in, sowing direct is a great way to add diversity without disrupting the soil biome or seedlings later on when they would need to be transplanted. As a general rule, seeds should be planted at a depth that is the size of the width of the seed, meaning that some of the smallest seeds are simply surface sown. Sand or squeegee sprinkled atop the freshly planted seed reminds us where they’ve been sown and protects the seeds from too much moisture loss in our dry climate. They should be watered once a week if moisture does not fall from the sky for the first year to help establish the plants and we should not expect blooms from the slow growing plants until the second year.
Native seeds love to be densely sown. Densely sown seeds of a single variety are more appealing to our cultural expectations for formal gardens as the resulting flowers and grasses grow in full bunches. For more wild areas, we can replicate a wild micro-meadow by sowing a mixture of wildflowers and grasses. Both techniques are beneficial to pollinators. Native grasses provide shelter and flowers offer nourishments through pollen and nectar. Pollinators need to learn how to drink nectar from different plant structures, so we can help them be more efficient by planting in bunches or bands so they can gather more from the repetitive action. Planting in bunches also allows us to harvest a greater diversity of seed from a single species. Once seeds are harvested, share them with neighbors or bring them to Native Seed Swaps hosted by the Colorado Native Plant Society to exchange for other natives you may not have growing in your garden to diversify species and ensure a constant rotation of bloom time.
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