</p> There are a number of plants that are clever enough to bloom during the winter months: none more predictably, nor beautifully, however, than the ill-named Christmas rose (Helleborus niger</em>). There are a few selections of this species that often begin to bloom in October or November most years, and yes, these may happen to be in bloom for Christmas. But invariably by January, I always have a few of these huge, waxy white flowers opening in my home garden. Mike Kintgen reports that they are blooming in the Rock Alpine Garden right now, and likely in one of the many other gardens where these are planted at Denver Botanic Gardens.</p> Helleborus niger at Denver Botanic Gardens Waring House, March 2011 So why not call these "New Year Roses"? a more apt and accurate name...oh well. Fat chance. Christmas has a stranglehold on the name. There is a whole industry in Europe cranking out Christmas cards with paintings of these lovely plants. I'm sure there have been tens of thousands of these over the years. I love the thick, leathery leaves, with their lyrate pattern almost as much as their blooms. The foliage makes a wonderful evergreen fountain of color year around, and make a graceful setting for these enormous flowers. I have seen these nearly 3" across in some forms: the petals are thick and waxy and simply gorgeous. Some age a deep rose red. It will bloom through thick or thin (and we are sure to have some very cold weather still) for the next three months: a marathoner if there ever was one! There is an enormous amount written about this plant in books, magazines and the web: worth browsing. It has accumulated great herbal lore (don't try it, though: it's very poisonous!), and a great deal of myth. I finish by saying that it loves Colorado, and should be planted by everyone here. Give it a good loam, enriched with a bit of humus in part shade. Don't let it dry out too much (especially the first year as it establishes). Once established in the right spot, this is quite tough, even somewhat xeric and likely to last in the garden for the rest of your life! (You can't say this about many herbaceous plants)...There are a wealth of hybrids of Christmas rose becoming available, not to mention a veritable revolution occuring with Lenten Roses: these, however, are mere distractions and side shows as far as I'm concerned: this is the Queen flower of winter. Let us bow down in wonder and worship! (I do anyway).</p>
From time to time, the greenhouse team at Denver Botanic Gardens will build hypertufa troughs. These troughs are a great addition to a garden, especially for showcasing some of the rock garden plants, native wildflowers, and cacti that might otherwise be lost in a larger landscape. We sell our planted troughs at the Spring and Fall Plant Sales and occasionally throughout the season at the Shop at the Gardens. However, if you are interested in making your own hypertufa troughs, I would like to share with you our process and recipe for making a simple hypertufa trough.</p> </p> Supplies</strong></p> For this project, you will need the following supplies:</p> Portland cement (either white or gray--if you are using a dye, the color of the cement will effect the dye)</li> Vermiculite</li> Sphagnum peat moss</li> Concrete dye</li> Synthetic concrete reinforcement fibers</li> A plastic mold, such as a large bowl, a cat litter tray or a dish pan</li> 1mm or thicker plastic sheeting (this can be a thick trash bag, a painting drop cloth, etc.)</li> Water</li> </ul> </p> Where to get supplies</strong></p> In the Denver area, most of these supplies are readily available. The peat moss and vermiculite can be found at most garden supply centers or at a large retail horticulture products supplier. The Portland cement, concrete dye and synthetic reinforcement fibers can be found at any specialty concrete supply store.</p> Supplies prep</strong></p> The task that will take you the longest in your trough making endeavor is the materials prep. The cement and vermiculite can be used as is. It is advised that the peat moss be sieved to remove large particulates and to provide a smaller grain material. However, if your goal is a coarser appearance, the sieving is not necessary.</p> The materials that take the most prep time are the synthetic fibers. When they are purchased, the fibers have the appearance of clumps of white strings. The fibers are added for stability and need to be consistent throughout the batch. To obtain this consistency, the fibers need to be ‘fluffed’ before they can be added to the mixture. This can be done by rubbing the fibers between your fingers until they take on the appearance of a pile of cat hair. It can be quite time consuming, but definitely worth the effort.</p> </p> Tools</strong></p> Dust mask</li> Rubber gloves</li> Wire brush</li> Propane torch</li> A bucket or container for measuring your dry ingredients</li> Wheelbarrow or suitable container for mixing the hypertufa</li> </ul> Mixing the hypertufa</strong></p> Once you have obtained and prepped your materials, it is time to mix the dry ingredients. It is advisable to always wear a dust mask and rubber gloves when working with Portland cement. We have experimented with several recipes; the following recipe is our favorite for strength and appearance:</p> 2 parts Portland cement</li> 3 parts vermiculite</li> 3 parts peat moss</li> 1-2 cups of dye (depending on the color you are hoping to achieve)</li> 3-4 cups of ‘fluffed’ synthetic fibers (this will translate to about a 1/4 cup unfluffed fibers). These fibers will not be added to the dry mixture; rather, they will be mixed in as you are adding water.</li> </ul> The size of the trough (or troughs) you are hoping to obtain will determine the amount of hypertufa you mix. If your goal is to make one small trough, the bucket you are using to measure out your ‘parts’ should reflect this size.</p> </p> Once you have mixed up your dry ingredients in the wheelbarrow/mixing container, it is time to add water. It is important to only add a little bit of water at a time; if your mixture becomes too wet, the end result will not resemble hypertufa. If you have a partner to aid in this process, the extra set of hands will be very helpful. While one person is using a shovel to turn the mixture, the other person can be incrementally adding water and synthetic fibers. This is also a good time to make any adjustments to the color of the mixture by adding more dye, if necessary. The desired result is a mixture that when squeezed in your hand both holds its shape and releases just a few drops of water. If you squeeze the mixture and it feels squishy or you can visibly see a lot of water forcing out, you have added too much water.</p> </p> Filling the forms</strong></p> Now that your mixture is ready to go, it is time to start making the trough by adding the mixture to the form (the plastic container) that you have chosen. As you will have to cover the finished project later with the plastic sheeting, it is a good idea to lay the sheeting down before you begin the molding process. As this is also a bit of a messy project, the sheeting will protect whatever surface you are working on.</p> In general, regardless of the size of your trough, you want the walls and bottom to be between 1-1/2 - 2 inches thick. Begin by adding shovelfuls of mixture to your form. This mixture needs to be compacted (to form the base) either by pushing with your hands or using a block of wood to push it down. If you do not compact the hypertufa, as it dries it will form holes in the trough and will generally lose stability.</p> As you are forming the base, start working your way of the side walls of the form. If the walls of your form are somewhat steep, it may be difficult to compact the mixture against the form. If this is the case, you can try compacting the mixture in your hands and then apply it to the inside of the form.</p> As you continue to build the walls of the trough, remember to keep the thickness consistent. It is very important that you make a drain hole in the bottom of your trough. If the trough is larger, you may want to make two or three holes. This is the best time to make the hole; if you forget, it will be necessary to drill it out once the trough has dried.</p> Curing</strong></p> Once you have molded the hypertufa in to the form and you are happy with the way it looks, it is time to begin the curing process. This is a two stage process; the first part lasts between 24-48 hours and the longer curing should take about four weeks.</p> Immediately after finishing the molding process, you will cover the trough with the plastic sheeting. Between 24 and 48 hours you will remove the trough from the form and leave it under the plastic sheeting. When to remove the trough is determined by the hardness of the mixture. If you can scratch it with your fingernail, it probably needs about 12-20 more hours. If you need a screwdriver to scratch the surface, this is about the right hardness. In general, smaller troughs take longer to cure than larger ones.</p> To get the desired appearance for your trough, this is the time when you would use the wire brush to rough up the outer surfaces of your trough. Most likely the plastic form will have left the trough looking shiny and smooth. Typically, hypertufa troughs have a rough and more weathered appearance. The wire brush will help you alter the texture to your liking. To make the trough as strong as possible, the longer curing method is recommended.</p> Once you have removed the trough from its form and altered the texture, place the trough back under the plastic and keep it at room temperature for four weeks. You will want to occasionally check the trough to make sure it is not drying out. If it feels dry, moisten it with water. After the curing process, if all goes well, you are ready to plant your trough! Remember to use well-draining soils and chose plants that are suitable for troughs.</p> </p>
</p> Colorado is reputed to have such a harsh climate that many trees could never grow here, like flowering dogwoods (Cornus florida) or Sweetgums (Liquidambar stracuiflua</em>). Once again, conventional wisdom is proved WRONG </em></strong> by Denver Botanic Gardens! We boast a fabulous specimen not far west of York St. in the Sensory Garden: I have admired this the last ten or fifteen years it has been growing rapidly, but only last year and this year has it finally fulfilled my expectations for fall color: right next to our only Sassafras</em>, it rivals that magnificent tree in its fiery foliage. Yes, yes...I know we had 8" of wet snow yesterday. Both Sassafras</em> and Liquidambar</em> (and most every other tree at the Gardens) came through very well. Everyone panics with our untimely snows (and we do get them every year!), but plants are resilient, and the better plants are almost immune! So keep planting better plants!</p> </p> "Boston ivy" (Parthenocissus cuspidata</em>) is not seen nearly as much as English ivy in Colorado. This Japanese cousin to Virginia Creeper is rather neater in growth form--rather resembling a deciduous English Ivy--and the fall color is often quite good. This year it has been exceptional. The Waring house positively glows!</p> Closeup of Parthenocissus cuspidata ("Boston" ivy) Every keen lover of fall color I speak to says the same thing: this has been a magnificent year for fall color. When Green Ash (Fraxinus pennsylvanica</em>), American elm (Ulmus americana</em>) and all the Lindens turn brilliant yellow and positively glow you know it is a really good fall color year. Combined with the ubiquitous scarlets of Freeman Maples (Acer freemanii</em>) and the glowing deep purple and gold of White Ash--which is also very popular--the street scene around Denver was very New England. I have a hunch that the show will continue well into November. Colorado does Indian summer with a vengeance, don't forget! With our Allan Houser sculpture exhibit, it is all the more appropriate it do so.</p>
</p> Certain plants have a certain "cachet" and Acer grandidentatum</strong></em> or bigtooth maple (with a host of other common names, usually alluding to some aspect of Utah where it is perhaps most abundant) is one of those plants. Imagine a petite Eastern sugar maple, only it tolerates alkaline soil and considerable heat and drought! That is a plant for all of us, I daresay! I heard it grew in Colorado near Mesa Verde, but several years ago a much larger colony was found by David and Pati Temple, who live south of Cortez.</p> This year I was extraordinarly lucky to be invited by David and Jeff Wagner (more about him anon!) to join them on a trek to find this new population in a place (I kid you not) called "Disappointment Valley." I hasten to tell you that this typically piquant Western place name is undoubtedly a ruse to keep the likes of you and me away. It is a splendid spot not far from the Utah line surrounded by magnificent wilderness and full of plant and animal treasure.</p> </p> </p> Here you can see one of the many picturesque buttes that form the backdrop to the valley. As far as I can tell, the substrate everywhere hereabouts is Mancos shale, a remarkably deep remnant of the Sea of Tethys from Mesozoic times. Mancos shale posses many properties: it is one of the slickest substances on earth when wet, and most remarkably it will turn people of middling height into towering giants (want to or not: I shall not tell you how long it took to clean our shoes off!). It grows plants well, as you can see.</p> Some of the maples we found were almost 40' or more tall, with trunks nearly a foot in diameter. The color was the most uniform crimson-pink I have ever seen on the species: I think this is definitely an area to explore further, and a place to get the hardiest, reddest of maples. In addition to bigtooth, there were gorgeous lemon yellow mountain maples thereabouts (Acer glabrum</em>) and even some pretty massive box elders (Acer negundo</em>). I kept looking to see if there might not be some intermediates around, but here I was truly disappointed!</p> </p> </p> A closeup of the man</em></strong>! David Temple and his wife Pati are two of Colorado's state treasures. They own an exquisite 3,000 acre ranch, much of it with conservation easements, boasting the highest, largest waterfall in the four-corner area. They have restored various ranches they own or have owned to a remarkable pristine look by their careful land management and sensitive farming practices. David grows hundreds of remarkable and often unusual trees for sale. I have some pictures of these I can share if you clamor loud enough...much of what he grows is available nowhere else. And don't get me going about their house and guest house--they are beyond lovely!</p> </p> </p> Jeff is a nurseryman who owns Four Corners Natives, a specialty wholesale nursery featuring a terrfic assortment of unusual and otherwise unobtainable native plants. He and his wife, Lisa Hollenbeck, hosted me this past weekend for an extravaganza weekend with the Durango Botanical Society. I am planning a blog about this hospitable and wonderful group that is creating an extensive Plant Select garden, a small botanical garden really, alongside the impressive Durango Library. I would be sure to put this on your bucket list of regional gardens to visit. I know you will not be disappointed!</p>
</p> Over the years visitors often say things such as "You must have everything at the Gardens!" Walking around on a beautiful autumn day like today that may seem the case. But in fact, we are missing many</strong></em> superb plants, both native and exotic. Filipendula</em> is a case in point: this genus of herbaceous Spiraea cousins includes a dozen or species widespread and abundant throughout much of the Northern Hemisphere... Filipendula</em> has been effectively AWOL from Denver Botanic Gardens for most of my tenure. Few plants are as adaptable, common in the trade and in nature. I confess that I have planted a few way back when, but I have noticed in recent years they are pretty much gone. These pictures were taken at a private garden at over 8000' near Conifer: proof that our members beat us at our game!</p> The queen of the genus is unquestionably the Queen of the Prairie (F. rubra</em>), one of the largest (it can be 8' tall when happy), showiest and most admired native plants of North America, largely confined to the Tall Grass Prairie of the Midwest. Like all the denizens of that biome, it was reduced drastically in its range when the prairies were busted for corn and soybeans. It is making a strong comeback in gardens due to its long season of midsummer bloom...if you want to see a spectacular clump like this one in Conifer, you will have to give it room, deep rich loam and lots of water. If you plant it, stand back! It spreads moderately by rhizomes to make a large, large, larger clump.</p> </p> This tiny cousin--barely a foot tall--could well be called the "Princess of the woodland," since it seems to need a tad more shade. It can be tricky to find in nurseries, even mail order!</p> </p> On the trip that Mike Bone and I took to Kazakhstan, several small, white flowered Filipendulas were everywhere in the steppe, in mountain meadows, along streams. Two were identified as F. ulmaria </em>and F. vulgaris</em>. Truth be said they look an awful lot like one another, and both resemble F. hexapetala</em>. Alas, white is not the most sought after hue (even this glowing, ivory white), although their ferny basal foliage is attractive throughout the season--especially in autumn when it can take on orange and scarlet tints.</p> These Filipendulas superficially resemble Astilbe</em>, although their flowers have a rakish, slightly tipsy look to them unlike the symmetrical spires of Astilbe</em>. Of course, filipendulas are in the rose family while Astilbes are saxifrage cousins. We collected seed of white filipendulas on the steppes of Kazakhstan which will be adorning several spots in Plantasia next year.</p> </p> You will find spectacular plantings of lupines in mountain gardens throughout the state, like these in Conifer. These are descended from wild species restricted to the Pacific Northwest, British Columbia and Alaska, so they seem to do best in cooler climates and at altitude. I have seen fine specimens nonetheless in Denver. These are a parting glimpse of that same mountain garden of two long term, enthusiastic supporters of Denver Botanic Gardens. Now perhaps if I can only persuade my colleagues to get these into our York Street and Chatfield gardens...(sigh</strong></em>)</p>
</p> I'm sure that if you told the next fifty people you met that "there are trillium growing wild in Colorado", I'm sure not one in a hundred would believe it. The picture above was taken last weekend north of Steamboat. Oh, so many stories! I had camped in this area for the first time nearly half a century ago. A bear tried to get in our tent (we kept the bear prints for years on the outside of the tent.) I went back many times since then. Early in this decade a colossal wind knocked down tens of thousands of trees in the Zirkel Dome area. Spruce beetle populations skyrocketed, killing all the healthy trees, and subsequent fires wrought havoc as well: I wondered if our trillium survived there?</p> Western white trillium (Trillium ovatum) last weekend near Steamboat. Many did! I could have spent days looking through the woods and tabulating trilliums. They are really quite common in the Montane and Subalpine forests of northern Routt county. As I peered from a distance at the remembered hills, I saw that much of the range of this plant is indeed changing: one of the hills near Slavonia which was filled with unusual treasures had burned just a few years ago... Unlike the eastern white trillium (T. grandiflorum</em>) which looks so similar, this trillium grows in very cool areas, often blooming near snow. Not a plant to grow in gardens, but a treasure to find again in the wild.</p> Trillium with snow (Trillium ovatum) </p> Three leaf bitterroot (Lewisia triphylla) There are no end of special plants in Moffat and Routt counties: this looks very much like pygmy bitteroot (Lewisia pygmaea</em>) only it comes from a bulb and grows at lower elevations. The only place in our state where you will find this miniature bluebell is in Northwest Colorado: the blue is piercing. What a cute miniature. We did not have time to seek out our native Rhododendron albiflorum</em>: next time... It would take a good many blogs to do justice to our state. This weekend it will be Central Colorado, with some tundra time: maybe I'll bump into you? Have a fabulous Fourth of July!</p>
</p> So begins a poem by the great 20th Century French Poet Guillaume Apollinaire (see below). I hasten to point out that the plants depicted (blooming right now at Denver Botanic Gardens) are technically not heathers (Calluna vul</em>garis--a single species from Northern Europe) but heath (Erica</em>--an astronomically larger group with hundreds of species mostly in South Africa). They're all very closely related, so let's not get too technical with common names, now. The pictured species from central and eastern Europe (Erica carnea</em>) is notable for many reasons: it is by far the hardiest of heathers, the one that loves limy soils and thrives in Colorado with only a modicum of supplemental irrigation: and best of all it blooms much of the late winter and spring. </p> </p> Erica carnea 'Vivelli' in Rock Alpine Garden</p> I've been disappointed in a few plants this spring: some of the bulbs have passed too quickly, and with our polar cold (-22F at my house) there has been winter damage, albeit far less than I feared. But the winter heaths are simply spectacular. I am distressed that plants that thrive so manifestly, that we have shown off so superbly at Denver Botanic Gardens for so many decades have literally languished in undeserved and pitiful obscurity, while Box Stores and even our noble local garden centers stock so many plants (how shall I put it tactfully?) of lesser merit. Considerably</strong> lesser</em> merit....ahem!</p> Fear not! You can buy these from many sources mail order! A great way to get plants, by the way (and with Paypal and the new convenient computer programs, you can be bankrupt in no time at all!). If you didn't get it, I linked the very best source subliminally at the start of this paragraph...</p> Now let's get back to literature: clear your throat, lean back and proclaim (in your very best French):</p> L’adieu </strong> </p> J'ai cueilli ce brin de bruyère L'automne est morte souviens-t'en Nous ne nous verrons plus sur terre Odeur du temps Brin de bruyère Et souviens-toi que je t'attends</p> Farewell</strong></p> I have plucked this sprig of heather / Remember herein that autumn has died / We shall never again see one another / Whiff of that time--a sprig of heather / And I still wait for you--remember! </p> Guillaume Apollinaire</p> </p>
</p> Closeup of star magnolia blossoms (Magnolia stellata) Aside from Townsendias and spring beauty (Claytonia</em>) the bulk of our native wildflowers are smart enough to wait until May, June or even later summer to bloom. Natives know that frost in Colorado can happen late in spring and early in autumn. But plants from Maritime climates have evolved where spring comes and stays. Such is the case with the fabulous spring flowerin g magnolias: these largely come from China and Japan where winter can be harsh, but spring usually arrives for good. Most years we are lucky to have a week of magnolia flowers before a hard frost turns the white or pink petals into brownish orange sludge...two springs ago, and last spring as well we had light frosts for weeks through March and April before summer made a definite arrival. Three springs of magnolia bloom is almost unheard of! Will we keep dodging the frost bullet?</p> Magnollia stellata</em> There are two stunning magnolias on the southwest corner of Denver Botanic Gardens' Waring house. They have been coming into bloom for several weeks, and the white star magnolia is in peak bloom as I type this. I have used these as "Poster Girls" of how NOT</em></strong> to plant magnolias: do NOT</em></strong> put them on the hot south side of your house (except, that is, for the evergreen sorts--these are summer bloomers that need extra heat to thrive here). Spring blooming magnolias are understory trees that do best on the NORTH</em></strong> Side of your house where their flowering is often delayed several weeks and they are less apt to freeze. It is also easier to keep their roots cool and moist, since these are emphatically not xeriscape trees... That said, our star and saucer magnolias bloomed through last year and the year before. And perhaps this year they shall dance their way past yet another volley of frosty bullets to delight and entrance us with their enormous, waxy, fragrant chalices! Get ye hence! And get more of these treasures to brighten up our springs, O Front Rangers! Our springs merit a lot more bulbs and gorgeous trees like this to celebrate the new growing season!</p> </p>
