Here at the Gardens, our horticulturists are always searching for new and charismatic plants to grow and display. This ambition leads our staff around the globe on exploration trips from Patagonia to Kazakhstan to observe, document and collect new plants and bring fresh information to the public. Although our focus can often be abroad, we recognize that there are also gardening challenges closer to home. In fact, some of our region’s most charismatic and abundant plants are frustratingly difficult to propagate, establish or maintain in garden settings. </p> For some plants, propagation is the problem: plants may germinate poorly from seed or suffer in greenhouse environments. In garden settings, our difficulty growing certain species may arise from an inability to create the necessary cultural conditions in the garden (e.g. soil drainage, soil chemistry, specific mineral substrates) or some other environmental mismatch between a plants’ natural environment and garden conditions (e.g. differences in temperature or natural precipitation regimes). However, it’s also clear that relationships with other organisms – bacteria, fungi and other plants – rather than environmental conditions per se, may underlie some horticultural disappointments.</p> For example, native lupines (Lupinus spp</em>.) are challenging to maintain in cultivation despite a broad geographic and elevational distribution and high abundance in native plant communities. Lupines, like other plants in the pea family, have symbiotic relationships with various root-associated microbes (including Rhizobium spp</em>.), which help them acquire nutrients from the soil. This raises the possibility that we are able to create suitable cultural conditions for lupine plants, but not for the associated microbes that they rely on. </p> Paintbrush (Castilleja spp</em>.) are similarly tough to grow in gardens because they are hemi-parasitic organisms, meaning that they rely on host plants to supply carbohydrates and other nutrients (see my other post, Paintbrush: Colorado's Vampire Plants</a>). Although their seeds are relatively simple to germinate, paintbrush will often behave like annuals, living for only a single growing season without a suitable host. Past research has shown that the identity of host plant is an important factor in survival of paintbrush in garden settings, but there is little empirical evidence to support specific host plant pairing recommendations and a poor understanding of how host plant identity affects long-term survival in cultivation. </p> To address these open questions, we’ve set up a controlled experiment at Chatfield Farms where we are trialing six species of Castilleja </em>native to Colorado matched with combinatorial treatments of six host plant species to assess how host plant identity might affect the performance of paintbrush under cultivated conditions. We are measuring the growth, survival rate and fecundity (seed production) of all Castilleja</em>-host plant combinations in the study over the course of three years. We have also completed germination and greenhouse experiments to hone propagation procedures and are using tissue culture to grow paintbrush and host plants together in vitro (in glass). This laboratory method allows us to directly observe the infiltration of Castilleja </em>into host plant roots and better understand the timing of Castilleja’s </em>parasitic behavior during plant development. </p> Our results are only preliminary, so we can’t share details right now, but so far we are observing stark differences in paintbrush survival and growth based on the species of host plant each paintbrush species is paired with These experiments will help us better understand how to optimize the growth and survival of paintbrush in cultivation. Hopefully as a result, you’ll see more Castilleja </em>on display at the Gardens—or even at our plant sales— in years to come. </p>
Now that it really feels like spring, some of our early pollinators are more visible: Honeybees have been active on warm days for a while, I’ve heard of multiple hummingbird sightings in the Denver area, bumblebee queens are foraging and building their nests, and mason bees should emerge soon as well. </p> We often talk about how to attract pollinators, such as butterflies and hummingbirds, to our gardens. I want to suggest a shift in thinking from attracting them to supporting them. Hummingbirds, for example, need more than nectar. We’re told to plant red, tubular-shaped flowers to attract hummingbirds, but the information stops there. While that nectar is an important source of energy for them, they need more than that. Hummingbirds also need protein. In fact, research suggests they need protein as much as, if not more than, nectar. </p> </picture> </div> </div> </article> Where do they get protein? Insects. This means that, in addition to nectar-rich flowers, our garden should promote healthy insect life. Reduce or eliminate insecticides/pesticides. Also, utilize complex plantings – mature trees (evergreen and deciduous), understory trees and shrubs, perennials, grasses – to create a multi-story garden. It doesn’t have to be big. But interplanting layers of these different types of plants creates a more complex environment to foster support for all stages of the hummingbird’s life. </p> This also supports insect life. Hummingbirds catch insects in flight, forage for them on plant foliage and steal them out of spiderwebs (maybe eat the spider, too). It provides them nesting opportunities and materials. Hummingbirds like to use spider webs in building their nests. Don’t forget to provide some water, whether it’s a pond, birdbath or just a bowl of fresh water. (And keep the cat inside!)</p> </picture> </div> </div> </article> Pasque flower</p> What’s blooming?</h4> Sand phlox (Phlox bifida</em>), creeping Oregon grape (Berberis repens</em>), manzanita (Arctostaphylos</em>), serviceberry (Amelanchier</em>), Pasque flower (Pulsatilla patens</em>).</p> What else can you do right now?</h4> Read “Pollinators of Native Plants” by Heather Holm and pick at least one new plant to add to your garden to feed pollinators in each season – spring, summer and fall. </p>
Spring flowers have begun to peek out of the ground and show their bright colors, and that means Mother’s Day is right around the corner! The Shop at the Gardens has just the right thing for the mom in your life. </p> Gifts are available in store</a> and through our online storefront</a>. </p> For the Décor Diva</h4> Cathy Frick Floral Art Tiles</a></strong> are each so unique and colorful in design. The 8x8 floral-painted tile is perfect to display on a table or mantel—or even hang on the living room wall. </p> Vase Wraps</strong> are not only the perfect gift to give, but also give back to the community. Lucy Grymes, the designer and name behind Vase Wraps, employs women from N Street Village, an organization empowering homeless and low-income women in Washington, D.C. (Only available in store.)</p> Outstanding baskets </strong>handwoven by a family in Ghana using elephant grass. Each basket is unique and different. The proceeds of each basket sold go directly back to the people of Bolga to provide resources they might not otherwise receive. (Only available in store.)</p> For the Fashionista</h4> The Shop features beautiful, unique jewelry</strong></a> </strong>for every style. Give the gift of glam this Mother’s Day. </p> For the Caffeine Aficionado </h4> Diversity Coffee</a> was established with the vision of providing customers with ethically sourced, superior quality coffee and exceptional customer service. This Jamaican Blue Mountain coffee is one of a kind. </p> Our signature Denver Botanic Gardens 9 oz. flowerpot mug</a> is sure to make any morning beverage a bit more cheerful. Coffee and tea just taste better in this cheerful flowerpot mug. </p> </p> Come on in to the Shop and see for yourself! Our trained staff is happy to help you pick out just the right gift. Don’t feel like going out? No problem! Cozy up on your couch and surf our online shop—new items arrive all the time. Members get 10 percent off orders, we offer curbside pick-up for local orders, and orders over $100 ship free. </p>
