Denver Botanic Gardens’ horticulture staff are frequently asked "What is there to see in winter?" The answer is "Plenty"! In addition to the bountiful winter-interest of dormant plants, persistent berries and coniferous cones and needles, there are also numerous indoor spaces to explore to satisfy your plant fix.</p> Immediately inside the lobby of the Boettcher Memorial Center </strong>you will find a beautifully designed planter filled with a variety of foliage plants. This space is a very low-light environment and can be a challenge for the horticulture team, but it also provides inspiration and ideas for visitors who struggle with similar low-light conditions in their own homes. Check back frequently to view new accent plants added for extra color.</p> At the west end of the Boettcher Memorial Center lobby, you will find the entrance to our largest indoor plant display – The Boettcher Memorial Tropical Conservatory</strong>. Home to hundreds of plants, this space highlights tropical plants from around the world. Palms and bananas stretch to the ceiling while species philodendrons, anthuriums and other tropical wonders fill the understory. There is always something in bloom</a> so come back often to observe how the space evolves through the year.</p> At the west end of the Tropical Conservatory, you will enter Marnie’s Pavilion</strong>. Here you will find more tropical plants surrounding a dramatic waterfall and stream. This space is accented with orchids and bromeliads rotated into the space from our behind-the-scenes collection greenhouses. A new addition to this space is a terrarium filled with many forms of butterwort (Pinguicula</em> spp.)</a>, a group of carnivorous plants that trap insects on their sticky leaves. More carnivorous plants can be seen on display in cases just as you enter the Orangery.</p> From January 12 to February 20, the Orangery</strong> will be filled with blooming orchids. This year’s Orchid Showcase</a> highlights not only the diversity of the orchid family, but also the diversity of the people involved in orchid research and cultivation. January is also a wonderful time to enjoy the fragrance of the blooming citrus trees.</p> Don’t forget to visit the Cactus and Succulent House</strong> in the southwest corner of the Gardens. Hundreds of plant specimens are on display in this cozy space.</p> In addition to the numerous plant displays, you can also visit the art galleries in the Freyer – Newman Center </strong>(included with admission) and before you leave, stop by the Helen Fowler Library</strong> (free admission to the library for members and the general public) to check out a book or two so you can continue your plant exploration at home.</p>
Winecups in Watersmart Garden</p> Strolling around York Street gardens this time of year, you are apt to see a bright rose red plant that resembles a geranium in many gardens. It is apt to be winecups (Callirhoe involucrata</em>), a favorite of many staff and keen gardeners in the area. Not a geranium at all, this is in the Mallow family, and another common name is "Poppy Mallow", although it's no more a poppy than it is a geranium. It is a native plant found sparingly on the Great Plains east of Denver, more commonly in the Midwestern prairies. It is a stellar garden plant that will survive with no supplemental irrigation once established...I see it occasionally as I drive around Denver--but not nearly enough!</p> Winecups in Highlands</p> Here is an amazing planting I found yesterday in Highlands neighborhood--easily ten feet across, completely filling one of those triangular hellstrip corners that are so often weed infested and neglected-looking (making neighborhoods look like slums). Here is a great alternative--a rock, a bit of Russian sage (Perovskia</em>) and an exuberant mass of winecups blooming for months on end--all with no supplemental water!</p> A closer look</p> This mass is growing in part shade--and the mound is almost two feet tallk, as opposed to the first picture in this series taken at Denver Botanic Gardens, in full sun--well less than a foot tall. It does need some room to ramble--but almost everyone has a spot where this can flourish.</p> Callirhoe involucrata v. tenuissima</em> Not everyone likes the hot magenta of the typical form of this species: there is a lighter, more pink form of winecups that is found originally in Mexico--sometimes classed as var. tenuissima. It does have even more finely divided foliage and a neater habit and the flowers often have a striking white eye--here seen growing in the Rock Alpine Garden as it transitions to the Gates Garden in the west. I am especially fond of this form, first introduced to cultivation by Yucca-do a few decades ago.</p> Closeup of tenuissima</em>.</p> You can see if you compare this with the next that var. tenuissima</em> is quite different in effect. Come to think of it, I think I need both in my garden! And I wish we'd see it a lot more everywhere in town: one of the toughest and most beautiful native perennials!</p> Closeup of var. involucrata</em></p> Here is a closeup of the typical form for comparison with the one above--both are really stunning! For sale in better Garden Centers (forget the Box Stores when it comes to native plants)..can be planted any time--just make sure it doesn't dry out in the height of the summer until established!</p>
Purple Mountain sun daisy at City and County Building</p> For over a decade the Master Gardeners of Denver and I maintained a low water garden</a> in front of the City and County Building in the Civic Center of Denver. It was with mixed feelings that I saw this replaced a few years ago with a much simpler, and rather classic garden design. A few days ago, as I drove past, I was startled to see a familiar flash of rosy purple pink: Surely that's not "Purple Mountain Sun Daisy?" I stopped and sure enough, Osteospermum barberiae</em> 'Purple Mountain'--one of the first hardy ice plants to be promoted in U.S. horticulture--was making quite a show. This was introduced to horticulture by Plant Select in 1998</a>--and has gained a steady following across the country over the interim.</p> Closeup of Purple Mountain</p> If you are not familiar with this plant, take a closer look. Photographs have a hard time capturing the distinctive and unique color--somewhere between hot pink and rich purple violet. The color is fantastic, and everyone loves it. There is a slightly darker ring around the disk flowers that make it even more alluring, and it does change hue every so slightly over the days that it opens. The reverse of the ray flowers is a silky bronze color--important because the flowers close at night or in dark weather. And while it blooms most enthusiastically from late April to mid June, there are scattered flowers on this lovely plant all summer long. Did I mention it has leathery, dark green evergreen leaves?</p> Purple Mountain bedded out</p> I take more than a little pride that the park's staff and designers have chosen such a prominent spot to showcase a plant that was debuted at Denver Botanic Gardens in 1991 (a few years later High Country Gardens began to sell this from germplasm they obtained from us). And now I see it popping up here and there around town.</p> Bank planting of Purple Mountain</p> I took this picture of a mass planting at a bank a few blocks from Denver Botanic Gardens a couple years ago--I noticed it's still going strong and blooming spectacularly this year again...</p> I've seen wonderful plantings in Pueblo and Vail--two utterly different environments: the plant obviously has a wide latitude of cultural tolerance. I have friends who have grown it in Massachusetts and California. Truth be said, it does seem sensitive to fungal or bacterial damage in some gardens. If you've had trouble with 'Purple Mountain', do try Osteospermum</em> AVALANCHE (see below).</p> Osteospermum AVALANCHE in the Mordecai Children's Garden</p> If you have never visited the Children's Garden at Denver Botanic Gardens (thinking it was only for kids), do not pass go, do not collect $200 Monopoly dollars--get yourself down there pronto! You will find amazing spreads not only of this gorgeous South African, but of all manner of wonderful montane and alpine plants that thrive in theCildren's Garden's green roof soil mix.</p> Denver Botanic Gardens can be proud indeed to have debuted such an important and uncanny group of perennials. The annual Osteospermums are well and good--but these hardy sorts make plush groundcovers, and bloom for months on end. Perhaps you should include a few in your garden? Who doesn't need a little Purple Mountain majesty above one's fruited plains!</p>
Fraxinus americana 'Autumn Purple' (White Ash)</p> "Disaster in slow motion" is a phrase that has been applied to many phenomena including global warming, the collapse of biodiversity, chronic drought...and most recently it's been appled to the Emerald Ash Borer (Agrilus planipennis</em>: henceforward referred to as "EAB") a green beetle from East Asia that was introduced accidentally in wood pallets in Detroit fifteen years ago. Since that time it has infested billions of ash trees in twelve states. The cost for removing dead ash from the urban forests of America is already climbing into the millions for even small cities, and the concomitant issues: thinning of the urban canopy, storm water abatement, air quality--these costs are hidden but real. No wonder when EAB was confirmed in Boulder only twelve weeks ago, arborists and decision makers across Colorado practically panicked. Ashes comprise around 15% of the trees in Colorado's cities: the cost for removing and replacing these trees over a short period of time is truly astronomical and daunting.</p> On Tuesday of this week, several of our staff joined hundreds of arborists from across the state and beyond at a daylong Emerald Ash Borer Management Seminar sponsored by Denver Parks and Recreation, the State Forest Service and Davey Tree. Several local authorities as well as those from some of the first areas affected by EAB gave very informative presentations that helped dispel some of the panic and provide some clear options. Several points that emerged were that because of Colorado's compartmentalization into different river drainages, the progress of the insect will likewise be compartmentalized. Since enough cities are separated by open space where ashes are not present, the progress may likewise be slower. A multiplicity of factors are showing that there are viable options for preserving many ashes with timely insecticidal treatments, and that a coordinated effort could preserve many ashes for a long time--rather along the lines of the strategy pursued with American elms--many fine specimens of which are still standing throughout our region despite the fungal infestation that destroyed nearly all of the elms in parts of the East.</p> Although there are compelling ecological and economic reasons to deplore this latest threat to our horticultural legacy--I came out of the meeting somewhat heartened by knowing so many professionals and decision makers cared, and that there were some practical strategies that will mitigate if not forestall this impending "disaster in slow motion". This link to a paper by Dr. Daniel Herms, Professor at Ohio State University at Wooster</a>, gives a good summary of the methods that will likely be used to preserve many--alhough by no means all--of the tens of thousands of ashes that grace Denver and the Front Range.</p> Ashes to ashes--but not yet quite to dust!</p>
Scott Skogerboe and mystery maple...</p> Everyone should have a hero. Scott Skogerboe has always been one of mine: Head of propagation at Fort Collins Nursery Wholesale</a>, he and his boss, Gary Epstein have been the force behind most of the woody plant introductions of Plant Select</a>. Here he is standing in front of...well...you shall have to wait and see (I have my crafty ways of making you read all the way to the bottom of my blog posting!)....</p> Amur maple at Box Store</p> This is NOT the same maple as the one with Scott above--this is an Amur Maple (Acer ginnala</em>) I photographed today (October 20) on West Colfax in front of a Box Store which I am NOT</em> endorsing (although I confess I did</strong> by 50 of awesome plants while I was there...). As the name suggests, Amur maples originate in the Amur river region of East Asia, the river that separates Manchuria from Siberia. No wonder the tree is so cold hardy! But that area is also Maritime--and the soils are podzoils: generally acid, more like the soils of our upper Midwest and New England. So of course, Amur maples in Denver are frequently chlorotic, and usually not recommended by horticulturists "in the know". No one bothered to tell the landscape architects, who filled the vast parking lot of this box store with them--and each and every one of them are blazing in DIFFERENT colors, and looking mighty healthy!</p> A whole ROW of frickin' amurs</p> Here you can see bits and pieces of a half dozen Amur maples in blazing color---looked like a regular conflagration! Each was robust, and each a very different shade of flaming red and orange (and some yellow and one or two green--this picture doesn't show them quite right--I'll show some closeups to better demonstrate a wonderful quality that is being increasingly denied people: namely, the wonderful biodiversity and variability that comes with seed grown plants.</p> Yellow-orange Amur</p> Although most of these maples were an unalloyed scarlet-vermilion, one was more orange-yellow in tint...</p> Green leafed Amur</p> Right alongside all the red ones, one had barely begun to turn and was still mostly green</p> Bright vermilion Amur Maple</p> But of the several dozen Amur maples around the parking lot, most were this flagrant, bracing, wonderful red color that we all love so much in the species. I have seen dozens of Amur maples all around Denver looking this good--there are some massive ones near Denver Botanic Gardens (and I have a pretty awesome specimen in my own garden too--hee hee)...but for every stunning Amur maple, there are usually a few gnarly, miserable things that look awful year around and hardly color up in fall. I have a hunch some of these are simply inferior plants, and others are probably growing in particularly bad sites with more alkaline soils, perhaps, or other environmental problems...Here, you should generate a drum roll and have the summon the cavalry with trumpets! Woo hooo!</p> Acer tataricum</em> at Fort Collins Nursery Wholesale</p> Last Friday, while visiting Scott at Fort Collins Nursery Wholesale, I espied a furiously red small tree in the distance--the same one pictured at the beginning of this posting with Scott standing in front. This is a superb, red-fall coloring Tatarian Maple--a sib to the Plant Select Introduction, Acer tataricum</em> Hot WingsTM</a>. I have observed around town that Hot Wings Maple has been quite reliable about turning a wonderful reddish purple color in most sites. And since it is a selection of Acer tataricum, it will thrive in far more alkaline pedocal soils ("Tatarian" refers to "Tatary"--the archaic term used for "Turkestan", the designation for the portions of Czarist Russia in Central Asia--namely contemporary Kazakhstan, Kirghistan, Uzbekistan and the smaller neighboring "stans" that are now mostly independent states, but formerly parts of Russia and the Soviet Union. Mike Bone and I found Acer tataricum</em> several times in Kazakhstan--many of them with the bright red samaras much like the Plant Select clone...</p> And here's the rub--you can go to almost any nursery in Colorado (in fact around the United States, Canada and Europe as well) and find Hot Wings in several convenient sizes--which you can purchase and plant in your garden and get not only spectacular fall color, but a shapely small tree the rest of the year which has brilliant red fruits for much of the summer--which look as bright and dazzling as flowers for an extended period: it is apt to thrive for you on acid or alkaline soils, and once established in Colorado thrives with almost no supplemental irrigation: what's not to love?</p> One of the great ironies of Colorado horticulture is that the ultimate seedsman (Scott Skogerboe) has also developed a number of clonal plants that will one day greatly outnumber the millions of seedlings he has grown in streetscapes and gardens around the world. Such are the ironies of our crazy modern world.</p> A piece of me wishes we could have developed a seed strain of red-winged maples so we could enjoy the wonderful biodiversity that thrilled me earlier today at Home Depot as I wandered through the Amur maples (imagining what they must look like in their native habitat right now, with the last few Siberian Tigers slinking through them nearby)--wait! What was that orange flash I caught out of the corner of my eye!? For a brief second I felt like Derzu Uzala</a> (you must rent this dazzling Kurosawa classic if you've not seen it yet) and a moist Siberian breeze caressed my cheek.</p>
Random sampling of Burr Oak Leaves</p> Our spring may have been the worst I can ever remember, but fall is shaping up to be extraordinary. Yesterday, towards the end of the amazing Pumpkin Festival at Chatfield I found myself wandering through the extensive windbreaks, most of which were planted twenty or more years ago by my friend Chris Hartung, who now runs an amazing nursery in Canyon City</a> with his wife, Tammy. It would be fun to walk the windbreaks with Chris and hear his stories: the trees have grown surprisingly well despite no irrigation, abundant bunnies, deer, elk and you name it in the way of herbivores. Even the "slow growing oaks" are getting some size despite the lack of irrigation! Burr Oaks (Quercus macrocarpa</em>) do not color brilliantly as most trees do in Denver: but they make up in rugged charm and wonderful leaf shape and acorn what they may lack in brilliance! Just look at the amazing variabillity in leaf color and shape in this very random sampling!</p> Burr Oaks at Chatfield</p> Denver Botanic Gardens at Chatfield is truly stunning: although the plant collections are still modest (the Visitor Center Garden--designed by Lauren and Scott Ogden, is world class, however, and large nevertheless), what makes a visit to Chatfield so gratifying right now are the wonderful vistas! The Rockies looming all along the West, the gently rolling countryside: it is our Secret Garden (although the tens of thousands of people coming to pick their pumpkins yesterday must have had an inkling! There were record crowds this year!)</p> Windrow of Burr Oaks: each one different!</p> It's great fun to stroll the windrows: every plant looks different. Some have already lost all their leaves, a few are still bright green. I wonder where the acorns were collected for these: are they from the Midwest? Or did Chris find a source from the wonderful Burrs that grow around Devil's Tower in Wyoming. On a recent visit to Gillette in early spring a few years ago, my hosts drove me up to the Devil's Tower and we walked around it (clockwise--the way you should walk around mountains of course!). This is the Westernmost colony of the tree in the northern Plains, and they were almost exactly intermediate between Gambel's and Midwestern Burr in character--some even stooling like a Gambels. The ones at Chatfield look more treeform (although still only fifteen or twenty feet tall at the max). I planted two burr oaks at my house about the same time Chris planted these and my Burrs are enormous now--one has to be over 30' tall and almost as wide and starting to take on the rugged adult form: three or four times the size and girth of these specimens: such is the power of irrigation!</p> Burr oak acorn</p> There were not a lot of acorns (the trees are yet young) and the ones I found were much smaller than the golf ball sized burr oak acorns I used to marvel at as a child in the park next to my house: those more than justified the common name "mossy cup" or "overcup oak".</p> An example of variability</p> This shows how variable the trees are: the one on the right was still mostly green, the one on the left is all brown and in the distance the burr oak is totally naked. All in proximity with what must be very comparable soil and exposure. Go figure!</p> Sprig of oak</p> For tree lovers, oaks and pines have a special resonance. If you've ever been lucky enough to see the massive burr oaks throughout the Midwest--all the way to the East Coast actually. Although I associate them especially with the magnificent oak savannahs around the Great Lakes and the rolling hills of the upper MIdwest. From a distance the white oak (Quercus alba) and burr oak look somewhat similar--but closeup the leaves and acorns are immediately distinguishable. Right now the handful of white oaks in Denver are a blazing, furious scarlet color (well worth their own blog!)--but even despite their superior fall color, it's the burr oak one finds here and there throughout our fair city. I believe the State Champion is just west of Cheesman Park--a massive creature that fills all the neighbors yards with leaves...(I know one of those neighbors and she's not to crazy about that tree)...</p> What sets this oak apart from many of Denver's street trees is its obvious drought tolerance. Chatfield's vast strings of windbreaks (so lovingly planted and cared for by Chris for years) are coming into their own: they make Chatfield a friendlier, more inviting place.. and they are teaching us a lot about the adaptability and variability of plants we should be planting more: the survivors!</p>
