September 30, 2010

Rare Tender Rhododendrons for Greenhouses

The hard to find Rhododendron 'Cinnkeys' has tubular blossoms that look more like a Cyrtanthus falcata from South Africa ( a bulb in the Amaryllis Family) than it does a Rhody. It can be awesome in a container, if you can find a plant. Image from the Quarterly of the ARS.

I am addicted to the Rhododendron species that are more tender, particularly those which require protection from the cold winter temperatures we get here in New England. If I lived in Seattle, Oregon, New Zealand or the United Kingdom where the climate is both cool in the summer, and winters are wet and temperate, growing these rarely seen Rhododendrons would not be a problem. But most of us live in areas where the temperature shift is too wide, where extreme heat or extreme cold makes any success with tender Rhody's nearly impossible.
The Rhododendron nuttallii form named 'John Paul Evans' is large, but magnificent when in bloom. At five feet tall when mature, it would require a redwood tub. ©singingtree gardens.

With a cold greenhouse like mine, where winter temperatures remain near 40 deg.F in the winter, I've discovered that tropical and tender Rhododendrons thrive. Most of them perform excellent in pots, where they can be hauled out in the summer and kept under the shade of trees. They must never dry out, but with proper care, many of these plants ( or small trees) can make spectacular specimen plants. There was a time when estate greenhouses and botanic gardens often had displays of tender Rhododendrons, but today, only a few people grow them as container plants, since modern homes  have atmospheres that are too hot and dry with central heating, and modern luxuries like insulation and reliable thermostats.

If you happen to own an old home, you may have some luck growing these plants indoors, with the best success coming from an unheated room, where there are large windows, and perhaps a window seat which has been converted into a plant window with gravel in trays for added moisture. Ideally, success will come easily with a glass greenhouse, or a conservatory, where the air is kept cool and buoyant.  If you are interested in more info, check out the American Rhododendron Society, and the Rhododendron Species Foundation for details and links to nurseries. For Vireya's, check out the Vireya net site.

The Vireya type Rhody named Rhododendron macgregoriae from the Vireya net site.

The classic Rhododendron species for conservatory culture in containers are the Asian species, particularly R. fragrantissimum, R.  Fragrant, bell shaped white blossoms, which include R. edgeworthii, R. nutallii and others. Perhaps the most tropical provide the brightest colors, and those would be found in the group known as the Vireya's ( most are native to the cool misty mountain slopes on the island of Borneo). Few nurseries sell Vireyas, but Bovees Nursery in Oregon is the number one choice, and this is the best time of year to order them.

Vireya R. crassifolium has unusual shaped flowers. ( Bovees Nursery)

R. macgregoriae ( from the Vireya Net)

R. sainpauli, a new species with very interesting flower. It would be great in a hanging wooden slat basket, as many Vireya like.
Vireyas make amazing potted plants, and of all of the tender Rhododendrons, are the best suited for cultivating on window sills and plant windows, as long as nights are cool, and moisture can be added to the air.

September 27, 2010

My Brunsvigia bosmaniae Blooms. A 'documentary experience', right in my own back yard.

BRUNSVIGIA BOSMANIAE Blooming in a large container

"Is it? Is iT? Oh my gosh! Oh my Gosh, Oh my gosh!!! It's a freaking bud" Was all Joe could here a couple of weeks ago, when I spotted what looked like a tiny bud emerging from one of the Brunsvigia bulbs that I had repotted carefully into a much larger pot. 

Brunsvigias are the queens of all of the South African bulbs. Large, showy, fussy, rare, they have everything that makes us collectors desire them even more. In a recent BBC nature documentary series in the UK, Sir David Attenborough describes how the inflorescence of the Brunsvigia bosmaniae, breaks off if its peduncle when dry, and then rolls along the veld dispersing seed as it goes. 

"Tonight, somewhere under the bright moonlight, perhaps in a broad,  sandy veld in the Natal area, a massive display of natures finest special event is happening. For every 7 years of so, a bloom flush with the genus Brunsvigia is transforming a valley which is normally just sand, into a sand bed with beach ball sized heads of pink lilies which will have the traffic stopping for days, and plat enthustasts with their cameras and new hiking boots snapping their digital pictures until the sun goes down each day. But here in our New England garden, something even more magical is happening. Four weeks before Halloween, just as the Macintosh Applies are being picked , a large English clay pot full of stone and sand presents us with a surprise and a very special gift. A massive head of pink lilies from a B. bosmaniae bulbs purchased then years ago for overseas, which has decided to reward us with it’s umbel of punk Lily-like flowers. Saying that we are delighted, would be an understatement. Apparently all of that coddling and special fertilizer really paid off.
The blooming of any bulb called Brunsvigia is big news, for these large, papery bulbs from South Africa are the queens of all bulbs, they reach enormous sizes, they are rare enough that when on blooms, it sometimes makes the papers and they require just the perfect amount of light, rain and rest, which can only be provided in the north with a glass house. 

Iconic to certain river valleys and dry lake beds in Natal South African, where local people wait decades to see one of the most magnificent sites in nature, the mass blooming of a large population of these plants, generally in a sand basin which is transformed into a sea of pink lilies. My one single bulb in a pot is hardly a veld, but I don’t care, I am so excited that I feel like  a new dad. Look, this is pretty big news around here I mean, there are probably only 5 or ten bulbs in private collections in our entire state, and few if any ever bloom.
The BBC Nature documentary 'LIFE'  featured a story about the Brunsvigia bosmaniae bloom in South Africa.

A wild population in Nieuwoudtville, South Africa blooming after a autumn rainfall, a phenomenon rarely seen.

In its native habitat, species of Brunsvigia, grow in a widespread area but mostly in the winter-rainfall areas of the Cape. When plants bloom ( usually in large populations), it occurs as a mass-bloom. The event is rare enough since there are a number of factors must occur ( sudden downpours after a long perious of drought, hot, searing summers, cooler evenings, perhaps even a full moon). Most botanists agree that the main trigger is a brief, heavy autumn downpour ( which in this area is not a guaranteed event), but if a rainstorm does pass over this dry area of Nieuwoudtville, botanists and plant enthusiasts know that the veld with be transformed precisely three weeks after the storm. 
We are more than thrilled about our Brunsvigia bosmaniae  blooming, since any guide to the cultivation of this genus will state that all Brunsvigia’s are notoriously erratic when removed from their native habitats. We can only hope that the other species in the collection bloom but it doesn't look like it yet. Best of all, it seems to be forming seed capsules. In it’s wild habitat, it is pollinated by nocturnal moths, but we’ve seen the honey bees on the blossoms all week so we are encourages that we may get seeds. Still, once sown, we will need to wait 12 years to see flowers from our seedlings, but hey, I might be retired by then!

September 24, 2010

The African Foxglove ( as if Africa has foxes ...and gloves).

Ceratotheca triloba is hardly 'new', it was popular amongst the informed British gardeners in Victorian England, and featured  by Jos. Hooker in an 1888 Curtis' Botanic Journal. For whatever reason, over a century later, we are just discovering the genus' contribution to our late summer borders. The only problem? Finding seeds of the easy to grow annual. Go find some now, for they will sell out in the spring.

 The African Foxglove, Ceratothica triloba, may not be a true 'Foxglove" (Digitalis) but does offer worthy color and structure in the early autumn border. The best thing is, no one will know what it is!
There are a handful of rarely grown annuals from the Southern Hemisphere worth trying, but Ceratotheca is perhaps the finest.

Oh dang... I SO want to type Cero-theca, but it's Ceratotheca. Take care in typing as you search for seed. I think 'Mr. Cerato', to aid me in remembering the name ( not unlike Ms. Sawyer's admission that she once used the phrase 'Mr. I'm A Dinner Jacket') to remember a world leaders' name.).
It's a trend...almost. Plant enthusiasts are discovering annuals from Chile and South Africa that are far from typical. Ceratotheca triloba, or 'African Foxglove', is a great example. This fast growing annual ( grows and blooms within one season, after starting from seeds in early spring) can make all the difference between a boring autumn border, and one that stops visitors in their tracks. They might even become jealous.