Now that it’s July and seedlings have had time to root in, container displays around the Gardens are taking off — bulking up in size, spilling over edges and launching flower stalks. Come with me as we wander among some of this season’s most colorful and dynamic displays. </p> First stop, the large containers outside the Bonfils-Stanton Visitor Center</strong>. Each pot is filled with citrus-colored flowers that echo the theme of neighboring beds – “So glad to see you,” a joyful hello to all who pass by. Although I chose the theme over a year ago, it has proven unexpectedly apt, reflecting the gratitude we feel welcoming visitors back. The highlight of this design is the tropical legume Senna didymobotrya</em> planted on either side of two cannas. Each plant has long stems that arch inward and, at distance, remind me of a person’s arms raised up in excitement before hugging a friend. Yellow, round flowers and leaves that smell like toasted corn give this beauty its common name, popcorn cassia. </li> Next stop, outside Marnie’s Pavilion</strong> where colleague Nick Daniels has transformed the low walls into a wondrous collection of cacti and succulents. This display encapsulates the principle that contrast is completion. It is diverse, unifying and satisfies our love of visual drama. Note how the variegated Agave attenuata</em> ‘AGAVWS’ Ray of Light pops in front of the brilliant red Aloe dorotheae.</em></li> From here we walk south to the Science Pyramid,</strong> where colleague Mike Holloway shows his talent for plant mixology -- combining cool and hot colors, spiny geometric forms and soft cascading ones. You’ll see more of his talents in the Victorian Secret Garden to the northwest, where kitsch is elevated to high art. Humorous touches — including a head planted with a bromeliad wig — are mixed with elegant combinations of foliage plants.</li> But first pass through the Steppe Garden</strong> to see an eclectic mixture of high-altitude gems displayed in front of the waterway. Colleague Sonya Anderson has assembled plants from four steppe regions, including a large pelargonium that looks like a tree and a king protea.</li> More must-see containers await in the Annuals Garden and Pavilion</strong>, where colleague Bridget Blomquist has lined beams of the pergola with baskets of silver dichondra, magenta geraniums and an Alternanthera </em>the color of red wine. The plants match those in planters below with equal lushness, making you feel as if you’ve escaped into a flower tunnel.</li> Next stop, South African Plaza</strong> where colleague Mike Kintgen transports us to the tip of Africa and nearby Madagascar and Sub-Saharan Africa. Here you’ll find flora that’s both familiar and unusual. Pelargoniums join lesser known specimens, such as Senecio </em>and Kalanchoe</em>, in pots on the terrace and in an adjacent bed of flowering torches, known as Kniphofia</em>.</li> Finally, walk through Le Potager,</strong> past a sea of larkspur to the gazebo and you'll find a container of Abutilon </em>‘Souvenir de Bonn’. Encircling it are wands of Campanula glomerata</em>, mingling so naturally with the flowering maple that you’d think they grew in the pot too. In fact, the campanula grows in the bed and the potted Abutilon </em>was placed there by colleague Ebi Kondo to create a seamless effect.</li> </ul>
Summer is officially underway. The cast of spring-blooming flowers we so eagerly awaited has been replaced by a rowdy and colorful mid-season crowd, who are having their day in the sun. And, while the initial excitement of the gardening season has not faded for many of us, reality has set in: weeds have proliferated alongside our beloved landscaping plants. Perhaps we were out of town for a couple of days, shifted our focus to a project other than our yards or needed a respite from the soaring 90°F temperatures. Meanwhile, weeds jumped at the opportunity, marched up and down sidewalk cracks and fence lines, colonized the darkest and most clay-heavy corners of our yards, and scrambled brazenly up desirable plants with their tendrils. </p> Some of these weeds are annuals or biennials that are easily addressed in an après-dinner weed-pulling session, accompanied with a beverage and snippets of conversations with friendly passersby. Pleasant enough. However, there’s that suite of more problematic weeds, perennials that reproduce vegetatively, creating clones of themselves until their radius expands. These are the weeds we pull repeatedly, only to become overwhelmed when they return with an exponential vengeance. One such weed is Canada thistle (Cirsium arvense</em>). </p> Identifying Canada Thistle</strong> A colony-forming species, Canada thistle emerges in the spring, punctuating yards (and other disturbed sites) with rosettes of leaves. Leaves are spiny lobed and from 4 to 8 inches long, mostly smooth and green above and white-woolly below. Around the time spring transitions to summer, a flower head emerges with one to five small pink to purple (rarely white) flowers. Fun fact: This species is dioecious, meaning individual plants have either female or male flowers. At maturity, Canada thistle stands 3 to 5 feet tall. What you don’t see is most of the plant—an extensive creeping root system that penetrates the soil to depths of 6 to 15 feet. </p> Since its arrival to North America several hundred years ago, Canada thistle has spread throughout much of Canada and the United States and is considered a noxious weed (list B) in Colorado. It aggressively competes with native plants, reduces crop productivity by vying for essential resources such as space, nutrients, light and water, is unpalatable to livestock and, if left to its own devices, can form monocultures in our yards. These are all compelling reasons to manage this species, but where to begin? </p> Research suggests that a combination of approaches works best for managing Canada thistle. Below are several suggestions: </strong></p> Mow frequently or cut back</strong> the rosettes with clippers </strong>from when the plant emerges in the spring through summertime. This will prevent flower formation and will also stress the plant by reducing carbohydrate storage in roots. </p> Glyphosate:</strong> From late summer up until the first hard freeze, spot treat by applying glyphosate to Canada thistle leaves using a paintbrush. The herbicide will be translocated to the underground parts of the plant, ultimately bringing about its demise. </p> Plant regionally appropriate plants:</strong> Once your yard’s thistle population is under control, plant regionally appropriate plants including a diversity of natives and Plant Select® plants. These require fewer inputs, including less fertilizer and water. Where bare ground remains, apply mulch. Covering bare ground with plants and mulch will make your yard less prone to future weed infestations. </p> Puccinia punctiformis</em>, a rust fungus that is host-specific and pathogenic to Cirsium arvense, shows great promise in managing Canada thistle populations.</strong> This biocontrol is currently being evaluated in Colorado for appropriate application timing and best methods. To learn more or to order, visit the Colorado Department of Agriculture’s Request-A-Bug</a> page.</p> Although Canada thistle is one of the more challenging weeds to manage, the good news is that with a multi-pronged approach over the course of several seasons, it is entirely possible to eradicate this weed from our yards. </p>
Shade is an essential resource for all life, providing refuge from the heat as the days grow longer. Denver Botanic Gardens has several shaded gardens where visitors can seek shelter from the intense Colorado sun. Under the canopy of trees that are beginning to leaf out, spring-blooming bulbs and perennials are freshly emerging from the soil and providing a glimmer of much needed joy to us all.</p> A shade garden truly shines in the spring in Colorado when blooming Crocus</em>, squill (Scilla </em>and Puschkinia</em>), Fritillaria</em> and Brunnera</em> begin to grow and bloom. They fill the garden with vibrant greens, blues, purples, yellows and reds that attract pollinators like bees and make us feel at one with nature. In a matter of just a few weeks, the shade garden goes from fully dormant to full of life!</p> Creating a shade garden requires patience, persistence and willingness to adapt, but this all pays off when the shade reduces solar heat-gain in a garden and on the surrounding property. A shade garden can lower cooling costs in the summer, retain irrigation and provide habitat for wildlife.</p> As a shade garden matures, thin areas within the tree canopy so that dappled sunlight reaches the ground below, allowing perennials and bulbs to grow their best. Late winter is an ideal time to observe the branching patterns of your shade trees and to prune them before new growth begins in spring. Soil structure is also pertinent in a shade garden as the trees and understory plants all share nutrients and moisture. It's best to avoid the use of chemical fertilizers and pesticides as much as possible; these products tend to damage the soil quality over time and reduce the beneficial microbial life within it. A quality organic compost or slow-release fertilizer will best improve soil structure over time and supplement the garden with essential macro- and micro-nutrients throughout the year. It is also important to select perennials and bulbs that are suited for shade when planting underneath the tree canopy. Hosta</em>, Heuchera</em>, Ligularia</em> and ferns are shade-loving perennials that thrive in low light conditions and benefit from the protection provided by the tree canopy.</p> As we near the heat of summer in Colorado, I encourage you to begin your own shade garden at home that will provide you with joy and relaxation for many years to come.</p>
One of springtime’s reminders that all is new are spring-blooming bulbs. Since our visitors cannot stroll through the Annuals Garden and Pavilion during this time when tulips and hyacinths are bursting, I’d like to share this virtual tour.</p> Begin your virtual tour at the main entrance to the Annuals Garden and Pavilion just south of the Oak Grove and Lainie’s Cutting Garden. To your right and left are a mix of Darwin hybrid tulips called Big Ups®. Darwin hybrids are the largest tulips available and are known for their huge blossoms.</li> Walk forward and find yourself under the large pavilion; to your left in the raised bed, notice the deep dark tulip. This Triumph tulip is called ‘Paul Scherer’. Gaze upon this blossom in the afternoon shadows and this darkest of purple tulips appears almost black. Interplanted among the tulips are Papaver nudicaule </em>‘Wonderland White’ (Icelandic poppies). Sorbet® Lilac Ice and Sorbet® XP Blackberry violas (Viola cornuta </em>‘PAS211805’ and ‘PAS867911’ respectively) add another lower carpeted layer of light and dark hues. Hyacinthus</em> orientalis</em> ‘Fondant’ and ‘Dark Dimension’ echoed this light and dark contrast when they peaked in mid-April.</li> Turning 180 degrees, notice the ‘Champagne Bubbles Pink’ Icelandic poppies (P. nudicaule)</em> popping their cheerful blossoms above the yellow pansies. You may be surprised to learn that the Icelandic poppies, pansies and violas planted in this garden were planted in the fall at the same time as the bulbs. These cool-season annuals provide color in the fall, overwinter, and re-emerge in springtime for an early blast of color.</li> Now walk to the south where three promenade beds greet you with a bold mix of orange and purple. Merry Go Round™ is a mix of three different tulip varieties: purple lily-flowered, purple double-flowering and orange double-flowering.</li> On the south side of the promenade beds is a long stretch of pale lilac-colored Triumph tulips called ‘Silver Cloud’. Named after the Rolls-Royce Silver Cloud model, this luxurious tulip does not disappoint. The stately tulips are adorned by fragrant hyacinths called ‘Blue Jacket’. Sturdy-stemmed Triumph tulips are a cross of early blooming and late blooming tulips to make a mid-season bloomed variety. About 3,200 bulbs are planted in this stretch surrounding Amelanchier </em>× grandiflora </em>‘Robin Hill’ (Robin Hill serviceberries), Alnus incana </em>ssp. tenuifolia</em> (mountain alders), Hydrangea</em> quercifolia</em> ‘Pee Wee’ (Pee Wee oakleaf hydrangeas) and Laburnum </em>× watereri </em>‘Vossii’ (goldenchain trees).</li> Look to the north of the promenade beds and you will find a sea of large apricot-colored Darwin hybrid tulips called ‘Daydream’. This raised bed boasts butter-colored and coral-colored hyacinths (Hyacinthus orientalis </em>‘City of Haarlem’ and H. </em>‘Gipsy Queen’) planted in between the tulips.</li> </ul> The garden is beautiful but there is something missing—our visitors. Until we meet in the garden again remember, “Hope springs eternal.” </p>
