Our Orchid Showcase (which runs through February 20th) features hundreds of orchid plants in full bloom artfully arranged throughout the entire Orangery.  The colorful blossoms are complimented by exotic bromeliads and other lush tropical foliage as well as citrus trees – many of which are also currently in full bloom.  Between the scent of the citrus blossoms and the bright colors of the orchid flowers, it’s easy to forget that it is still winter. 

Unless of course it is snowing outside – but this only makes the warmth and coziness of the Orangery all the more enjoyable.

 If you’d like to learn a bit more about growing orchids, we are also offering free orchid repotting demonstrations each Saturday and Sunday afternoon at 12:30.  Just drop by Marnie’s Pavilion and a Horticulture staff member will be on hand to help ease any anxiety you may have about repotting and caring for orchids.

The Orangery at the west end of the greenhouse complex has quickly become one of my favorite new spaces at Denver Botanic Gardens.  Sitting on a comfortable garden bench surrounded by beautiful lush plant life is especially enjoyable on a cold winter day.  It’s not often you can enjoy hundreds of orchid blossoms interspersed with blossoming citrus trees juxtaposed with snow covered pines just a few feet away.  I hope you will find time to pay a visit soon.

In lieu of shiny catalogs, botanists, like myself, and mycologists work with specimens (mycologists study organisms in the kingdom Fungi). Specimens are individual plants or fungi that have been dried and archived into a collection. These plants and fungal specimens are collected as part of a scientific study to document species diversity and distribution.

The specimens themselves serve as a voucher or as a representative of the population for future botanical and mycological research. For botanists, anxious to get out into the field, specimens allow us to continue our work even when the plants or fungi are dormant for the season. Likely for this reason, in the 1500’s, the Italian botanist and physician Luca Ghini developed the practice of preserving plants by pressing and drying them when freshly collected, and then  ‘mounting’ them onto paper. For fungi that produce large reproductive structures like mushrooms, the reproductive structure is preserved. Initially, mushrooms were pressed and dried like plants but now they are dried without pressing so that they retain their three-dimensional structure.

Specimens are more than just scientific value. If done well, they are also beautiful works of art. In the Victorian Era (the heyday of botany) many botanists created lovely bound books of specimens. Sometimes, specimens were accompanied by drawings or watercolors of the plant or its habitat, or different plants species were combined on one page to create a bouquet. As my fellow botanists and I at the Gardens continue our work during these cold winter days, specimens offer more than great science but also a delightful piece of art.

If you’ve ever been interested in learning more about (or being involved with) herbarium collections, join instructors Melissa Islam & Vera Evenson, for  two unique and exciting classes coming up at the Gardens.

The Art & Science of Fungi Herbarium Collections: Tuesday, Feb. 28 (6-8 p.m.)

The Art & Science of Plant Herbarium Collections: Tuesday, March 13 (6-8 p.m.)

Guest Blogger (& Instructor for the Plant & Fungi classes):  Melissa Islam

Melissa is the associate director of research and head curator of the Herbaria at the Gardens. She studies the evolutionary relationships of plants and helps to document plant diversity in Colorado through floristic inventories. Melissa spends much of her time in the winter working with dried plant specimens or tubes of plant DNA.

Instructor (Fungi Class): Vera Evenson
Vera Evenson (Fungi Class) – Vera is the curator of the Sam Mitchel Herbarium of Fungi and works tirelessly to identify the mushrooms in the collection. She is an expert on Colorado fungi and has written the popular book “Mushrooms of Colorado and the Southern Rocky Mountains.”

A Tangelo blooms in the Denver Botanic Gardens Orangery in winter.

Winter is busy, and not just for Colorado skiers. Gardeners are planning, dreaming and preparing; growers are tending indoor blooms; and propagators are starting plants to be ready for warm weather: busy! Evergreens are balancing photosynthesis and drought, orchids are delivering on the promise of color and beauty, and seeds are trying to intuit the fine line between germinating too soon and too late: busy! For some gardeners, winter means that their busy, short days can’t hold time to appreciate each bloom and everything that is happening.

You can’t always look ahead either.  It was pure chance that I saw this white Tangelo blossom on a snowy day.  (The Orangery at the Gardens looks lovely with the orchid showcase throughout.)  But it didn’t look like a random chance for the two knitters I saw perched on a bench.  They had obviously come to spend time talking and knitting and enjoy a panaoramic view of the falling snow from a warm, citrus-scented enclosure.  And I suppose that is the trick to surviving most busy time: prioritize and make time for what you really want.

This weekend alone hosts many happenings. Cord and Penn Parmenter are teaching Sustainable Greenhouse Design and Passive Solar Greenhouse Growing.  In Fort Collins, The Gardens on Spring Creek is presenting Marcia Tatroe, longtime Denver gardening author, and Dan Johnson, curator of native plants at Denver Botanic Gardens.  Marcia will speak about “Four Seasons in the Xeric Garden” and Dan will present “Meet the Natives: Bridging the Gap between Trail and Garden.”  I think of all the fun they’ll have and want to be in two places at once!  And then, all the new information is just in time to layout a springtime garden plan.

Its no wonder the USDA released the updated zone map this month–it is so busy there’ll barely be time to prepare!

Helleborus niger, blooming January 26, 2012 at my house

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). 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.

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).

Aloe harlana

Aloes are widely available through many nurseries locally as well as mail-order nurseries online.  The amount of beautiful hybrid Aloes will send your head spinning!  They are quite easy plants to grow as long as you do a little research into the particular plant you have.  For the most part, Aloe like to be watered regularly, as long as they are allowed to dry out between waterings.  They are not heavy feeders, and appreciate a well-draining mix and a bright sunny spot.  The more sun they receive, the more reliably they bloom, and the more colorful their leaves become.  Aloe are not hardy in our cold Colorado climate, but they do love to be displayed outside during the warmer months, and in fact, benefit from the bright sun, as long as they are returned to their windowsill before the danger of frost.

Many of us are familiar with Aloe vera.  It’s healing properties are quite well documented, but be aware, not all Aloe share these medicinal properties. Never rub Aloe sap on a burn or on your skin unless you are certain it is Aloe vera.  Some Aloe have toxic sap that would likely do more harm than good on your skin.  Aloe ferox is another species with medicinal properties, although it is more uncommon to find.

Aloe parvibracteata

So, if you’re in need of some winter color in your house, start an Aloe collection!  Many of the hyrbids are sized perfectly to fit into a window sill and come in every color one could imagine, do a little searching online and you’re guaranteed to find an aloe or two to suit your needs.  Happy gardening!

In a previous blog post I described how before germinating many seeds commonly go through dormancy which can last a few weeks, a few years, or even a few decades.  Those patiently waiting dormant seeds are collectively referred to as the seed bank. 

How many dormant seeds exist in any given place depends largely on how often the area is disturbed.  Because long-term dormancy is an adaption that helps seeds to germinate during the best of variable conditions, ecosystems with stable climate or few physical disturbances usually have relatively small and/or transient seed banks.  Seeds simply have few reasons to wait in such places (beyond waiting for the correct season to germinate).  Ecosystems with more variable climate or more frequent disturbances tend to have much larger seed banks.  Most of the temperate globe falls into this category. In The Origin of Species, Charles Darwin observes that an astonishing 537 seedlings appeared over 6 months in three tablespoons of soil he collected from an English pond margin.

In places that are very regularly disturbed or that have been very recently disturbed, the species represented in the seed bank usually closely match those growing above ground.  As the process of ecological succession continues, though, the species composition of the seed bank diverges from that of the above ground flora.  Thanks to the seed bank, the earlier species aren’t necessarily gone for good. When new disturbances occur, be they fire, burrowing animals, road-building mammals, or erosion, species that may have been absent for years can reappear from the “plant diversity savings account” to take advantage of the upheaval. 

Photo: Penstemon thrive in disturbed soil.

In Colorado, beardtongue (Penstemon) species thrive in disturbed soil but will disappear as plant communities mature.  Where patches of earth have been disturbed, though, beardtongue will reappear, often after years of absence. Many noxious weeds take advantage of disturbance in the same way, which is why minimizing disturbance in wild areas is often a component of weed management plans.

Colorado is also home to a rather unusual seed banker—lodgepole pine (Pinus contorta var. latifolia).  While many trees release their seeds annually, some individuals’ cones remain tightly closed on the tree for years beyond when they mature, only opening after fire.  This strategy, used by plants in ecosystems with regular fires all around the world, ensures that seedlings will have ample light and nutrients in the recently cleared ground. 

Photo: A dense lodgepole canopy can prevent germination.

Seed banks help keep our wildflowers blooming and our forests young, but your relationship with them might be closer than you think.  The seed bank can be the source of some gardening-related frustration:  persistent weeds.  Seed banks, and particularly those of weeds, can be quite large in gardens because cultivation handily retires seeds to deep repose and then resurrects them at regular intervals.  Even if one is diligent about removing weeds from the garden before they flower or set seed, new offenders can sprout year after year.  The only option is to remain diligent and wait until the seed bank exhausts itself.  Considering that in one experiment some species of mullein and mallow remained viable in the field after 80 years, it could be a very long wait.

This post is second in a series, “Four-Minute Ecology.”  New columns are posted every other Tuesday.

Cord finished building a 44’ state-of-the-art totally sustainable passive solar greenhouse late last August and the owners lost no time in getting tomato plants in the ground soon after.  They planted large potted tomatoes in deep beds at the base of the wall of stored water – the thermal mass.

Now, in January, they are 10 feet tall and bursting with tomatoes.  Not only were they grown in winter – but with passive solar.  And, oh yeah, at 8,000 feet in the mountains!

No tomato ever tasted so good.  The juice ran down our chins.  I started laughing while I was eating them – trying not to inhale them and choke.   I never truly understood what it is like to be on the receiving end of such a gift.  I felt the circle complete with those tomatoes – and a great sense of happiness with every bite.

You, too, can provide such a delicious gift to others (or yourself!) by taking Penn and Cord’s Passive Solar Greenhouse Design.  They will be offering the class twice this winter – Saturday, Jan. 28 (10 a.m. – 2 p.m.) and Saturday, March 10 (10 a.m. – 2 p.m.). Penn and Cord are wildly popular teachers so be sure to register as early as possible!

Complete list of upcoming Parmenter classes:

Sustainable Greenhouse Design: Saturday, Jan. 28 (10 a.m. – 2 p.m.); Saturday, March 10 (10 a.m. – 2 p.m.)
Passive Solar Greenhouse Growing: Saturday, Jan. 28 (3 – 5 p.m.); Saturday, March 10 (3 – 5 p.m.)
Mountain Food Growing: Sunday, Jan. 29 (1 – 5 p.m.)
Saving & Adapting Seeds to High Altitude: Sunday, March 11 (Noon – 2 p.m.)
High Altitude Strategies for Vegetable Growing: Sunday, March 11 (3 – 5 p.m.)
High Altitude Garden Tour: Friday, May 18 (Noon – 2:30 p.m.)

Guest Blogger: Penn Parmenter

Penn and her husband, Cord, will be instructing the sustainable greenhouse class at Denver Botanic Gardens. Penn and Cord have been gardening and growing food in the Wet Mountains north of Westcliffe, Colorado since 1992. Their three abundant gardens sit on a mountain at 8,120 ft. and feature numerous high altitude growing methods.

Visit their website at pennandcordsgarden.weebly.com.

Seed is collected either ‘dry’ or ‘wet’.  The ‘wet’ seed (think of saving seeds from tomatoes, squash, or even some species of fruit- or pod-bearing trees) is processed and cleaned almost immediately.  However, the ‘dry’ seed is collected from a plant once the inflorescence, the showy petal part of the flower, has dried up and the ovary, containing the seed, has begun to harden.  In some species, such as the opium poppy (Papaver somniferum) featured below, it is very easy to locate the ovary containing the seed.  In other species, such as a yarrow (Achillea spp.) shown below, the ovary and seed are much smaller and it can be difficult to know which part should be saved.

Once these parts of the plant have been collected, they are stored in paper bags to allow them to continue to dry out.  These collections might sit for up to six months before they are cleaned; as long as they are kept in a relatively dry, cool room, this will not affect the long-term viability of the seeds.  Because it is often easier and less time consuming to collect the seeds with large sections of stems, these bags will be filled with both seed and chaff.  Chaff is any part of the plant, including stem, leaves, and petals, that needs to be separated from the seed.

In order to separate out the seed from the chaff, we use a variety of methods, some time-tested and some a bit more home spun.  The basic techniques are threshing and winnowing.  Threshing is the process of breaking up seed pods to release seed.  Some examples of threshing are rubbing the seed pods between your hands, lightly grinding the pods with sandpaper or rubber blocks, and, in the case of some very hard seeds, striking the pod with a hammer.  Once the seeds and chaff have been threshed, winnowing can be used to sort the chaff from the seed using wind.  In our lab, we use a hand-held blow drier and a set of geologic sieves to accomplish this task.  Larger operations use equipment such as gravity separators and modular air screen machines that are able to separate seed from chaff by programming the weight of the seed into a machine.

In some cases, winnowing and threshing are not enough to finish the job.  Often times, the final step in cleaning a sample of seed is removing the chaff by hand.  This can be time consuming, but storing your seed in the cleanest state possible will help prevent decomposition of the seed over the term of its storage.  Even after the seed has been cleaned, we store it in paper envelopes (rather than plastic) to lessen the chance of molding caused by seeds that contain too much moisture.

In general, we keep our seeds in storage for about five years.  During this time, the seed will most likely be grown for use in one of our gardens or for sale at the Spring or Fall Plant Sale.  There is also a chance that it will be requested for use by a different botanic garden through our involvement with the Index Seminum program that allows for seed exchange among public gardens in the international community.

As our seed collection efforts have increased over the past five years, we have moved into the next phase:  creating a seed herbarium containing all the wild and garden collected seeds in our collection.  This catalogue currently only exists in physical form, but we hope to someday soon move it to a digital format.