Friday, May 20, 2016

Conifers in GH28

Our greenhouses are not necessarily arranged in order because they are numbered in the order that they were built, regardless of location. GH25, 27 and 28 are all about 100 yards away from each other, but what they do have in common is that they're all full of conifers. New plants are in them, as well as many which aren't hardy at a young age. Let's take a walk through GH28 and see what's there.

Cupressus cashmeriana at the J.C. Raulston Arboretum

The first encounter is Cupressus cashmeriana, the “Weeping Cypress of Bhutan.” My start came from a Canadian nursery about 25 years ago, and I could see that the perfectly-compatible rootstock was Thuja occidentalis 'Smaragd'. For some strange reason C. cashmeriana is less compatible with Thuja occidentalis 'Pyramidalis', when you would think that the understock species is all that should matter, not the cultivar. Rushforth in Conifers (1987) states, “Kashmir cypress” makes a very attractive tree but unfortunately is very tender and only survives for more than a few winters in Ireland or the mildest part of Britain. It is an excellent plant for use in a conservatory...” I remember seeing it 13 years ago at Kew in their fabulous conservatory, and it was not so far from reaching the top of the huge structure. In the Hillier Manual of Trees and Shrubs (2014) they claim that they have a 10m specimen planted outdoors that is 30 years old. I was most surprised to see an outdoor specimen at the J.C. Raulston Arboretum in North Carolina a few years ago, where it hardily withstood 7 degrees F. C. cashmeriana is not known to be native to Kashmir in northwest India, yet it was introduced from there in 1862. Was there a thriving horticultural scene in India before the British got there?

Tsuga mertensiana 'Bump's Blue
Dr. Bump with 'Bump's Blue'

Tsuga mertensiana 'Blue Star'

Tsuga mertensiana is probably my favorite conifer, probably because I'm not slaving away at the nursery when I am out goofing off in the Oregon Cascade Mountains. There is one particular colony of a thousand or so on the western flank of Mt. Hood. They range in size from little guys to 50' specimens, usually slender, and I think I have met nearly every one in this family. We never had much luck selling the straight species, but cultivars like 'Bump's Blue' and 'Blue Star' are in high demand. The only problem is that it takes about 12 years to achieve 6' in height, so they're not very profitable. The main reason that we grow them indoors is to encourage more growth from the lush conditions when they are small. The late Dr. Bump dug what became 'Bump's Blue' out of the ground at Mt. Hood about 50 years ago and planted it in his garden; certainly illegal today, but back then gardeners did whatever they wanted. 'Blue Star' was selected by L. Konijn of the Netherlands in 1965, and I saw a nice specimen at the Gimborn Arboretum. Be careful to not mix up these two cultivars, as you might not ever be able to tell them apart. The mertensiana species was introduced to Britain by Scotsman John Jeffrey in 1851. He arrived at Hudson Bay in 1850 and then travelled all the way to the Columbia River. He explored and collected in Oregon, Washington and California for four years, sending the goods back to Scotland. Then in 1854 he disappeared while crossing the Colorado Desert from San Diego, never to be seen again. Jeffrey met his maker at an age younger than I was when I began Buchholz Nursery, nevertheless he is honored for Dodecatheon jeffreyi and Pinus jeffreyi. If he had not been the first to introduce Tsuga mertensiana, eventually someone else would have, but cheers to Jeffrey for discovering a species that eluded fellow countryman David Douglas. These collectors died too young, but I suppose that they both sucked a lot of marrow from the bone of life before passing.

Chamaecyparis lawsoniana 'Blue Surprise'

Chamaecyparis lawsoniana 'Imbricata Pendula'

We always grow Chamaecyparis lawsoniana cultivars indoors for a few years, then when they're in a 7 gallon pot or larger we lack the room inside and kick them out to the Box Area. The species is hardy to USDA zone 5, or -20 degrees, but that is in the ground, and young plants in containers can perish with temperatures as low as 10 degrees above zero. Heck, we even had Picea pungens cultivars – three year old – die in one gallon pots when we reached 0 degrees with 30 mph winds, and they were grafted onto USDA zone 2 (-50 degree) Picea abies. The lesson was learned: protect the lawsons when young, inside. GH28 contains the cultivars 'Blue Surprise' and 'Imbricata Pendula', and certainly these two consist of the most wildly diverse examples of selections within a species. 'Blue Surprise' is a sparkling silver-blue dazzler with a narrow pyramidal habit that broadens at maturity, and be forewarned as a dump of wet snow can screw everything up. 'Imbricata Pendula', on the other hand, gives snow no purchase on its slender branchlets as it casually disses the wintery fluff. An elegant specimen – 30' tall? – exists at Flora Farm, and I purposefully planted it close to the road as a visual gift to the public. We all know that pendula means to “hang down,” as in a pendant; while imbricata is from Latin for “arranged with regular overlapping edges,” as in roof tiles or fish scales...ultimately from imbric for “roof tile,” from imbr for “rain.” I have seen the cultivar in Europe, happily thriving on its own roots, but in America one should propagate it – and all lawsons – on disease-resistant rootstock...and shame on all of the American nurseries that do not! These hucksters – and I have an urge to call them out – certainly know that the majority of their C. lawsoniana cultivars will die once the public puts them in the ground, yet they produce them (profitably) anyway. Look, I know I have my faults and short-comings, but I have never knowingly screwed the gardening public. I have too much respect and appreciation for your enthusiasm and support for my plants; and hey, thanks to you, I never had to get a real job.

Xanthocyparis nootkatensis 'Nidifera'

Xanthocyparis (formerly Chamaecyparis) nootkatensis is native from Alaska, down to northern Oregon, with an outlying population in central Oregon on Mt. Aldrich. There are a number of cultivars which are known to be more dwarf, narrow or variegated than the type, but 'Nidifera' – found in Italy before 1889 as a seedling – is very different, so much so that it was once considered to be C. lawsoniana nidiformis, Thujopsis nidifera, Cupressus nidifera and Thuja borealis var. nidifera. It forms a spreading nest-shaped bush with lovely blue-green foliage. We prefer to stake ours as they will then develop into small weeping trees. In the past we propagated by hard-wood cuttings in winter, but now we prefer to graft onto strong, hardy Thuja orientalis, and our crop responds with more uniformity and vigor. I got my start from the Bedgebury Pinetum in England about ten years ago, and before that I had never seen it. It is still rare in the trade, and I know of no one else in America who produces it. Most of my customers who have bought 'Nidifera' have ordered after first seeing it here, for it displays very appealing foliage.

Dan Luscombe discovering Pinus contorta 'Mt. Hood Variegated'

Speaking of Bedgebury, Dan (not Don, Hillier) Luscombe is employed at the Pinetum. He was in Oregon a few years ago and we made a car trip around Mt. Hood. At one point he exclaimed that he saw a variegated pine, which at that elevation could only be Pinus contorta. It took me awhile to turn the car around, then we scoured the road bank, all the while Dan fretting that maybe it wasn't what he thought. To his relief, “there, there it is!” Not only was it variegated, but prettily so with its grass-green shoots with about a fourth of them colored clear yellow. I returned later that winter, and with no park ranger in sight I quickly cut a couple of scions. My activity posed absolutely no harm to the tree, but government employees don't usually reason with knowledge and common sense. I haven't officially named it yet, but it does have a label that reads 'Mt. Hood Variegated' so I can keep track of it. The pine still has not been trialed outside, and even though it looked good at 5,000' elevation, it's a far different world there than at my baking nursery. I'd like to send a start to Dan to trial at Bedgebury, but unlike the old days when everybody did what they wanted, there are probably rules prohibiting the sending of pines.

Picea orientalis 'Tom Thumb' outside

Picea orientalis 'Tom Thumb' outside

Picea orientalis 'Tom Thumb' in shaded greenhouse

Picea orientalis 'Tom Thumb' is considered the correct name, not 'Tom Thumb Gold'. Nevertheless it is a golden miniature that originated as a witch's broom on P.o. 'Skylands'. 'Tom Thumb' grows between one and three inches per year, so I keep my stock inside hoping for three-inch scions. It requires a good deal of sun for best color, then afternoon shade so it won't burn. One photo (above) is from indoors, so you can see that it's not so bright, but as a stock plant I don't care. I like all cultivars of the “Caucasian spruce,” but surprisingly they don't root, at least for me. We can't root Picea omorika either, when Picea glauca and Picea abies are relatively easy to root. If anyone wants to brag otherwise I would be happy to know.

Chamaecyparis obtusa 'Bess'

Chamaecyparis obtusa 'Bess' is my favorite of the upright hinokies, and it grows about an inch per year. The best attributes are its dark green foliage and narrow habit. The retired John Mitsch gave me my start about ten years ago, and he reckoned it to be about 35 years old then, and now it is only six feet tall. John told me that it was discovered by Joe Reis and named for his wife Elizabeth who was affectionately called “Bess” by her husband. The late Ed Rezek gave me a similar seedling (from 'Nana Gracilis'), and it sits proudly in the garden across from the office. 'Rezek' is a faster grower and more broad at the base than 'Bess'. Once again I just temporarily named it 'Rezek', but then I began to sell it as such even though I'm the one who preaches against naming plants for people. In an open garden setting it is fun to sow seed from 'Nana Gracilis', and you're liable to get dwarf or golden or fast green progeny. I have introduced five C. obtusa cultivars but all of them were the result of a branch mutation – 'Harumi', 'Lemon Twist', 'Moonshine', 'Snow Blast' (horrible) and 'Sunshine', with 'Lemon Twist' probably being the best.

Chamaecyparis pisifera 'Harvard Gold'

John Mitsch

I have mentioned frequently that John Mitsch was extremely generous with me throughout my career. He gave me a Chamaecyparis pisifera that he was pleased with, but he had no intention to propagate it and he supposed that I would. He got his start from someone on the East Coast, but apparently it was never in production. Hopefully my story is correct but I can't be certain. Originally I called it 'Mitsch Gold' – there I go using people's names again – but I saw John a few years later and I brought up the naming of the pisifera. He said, “Well, since it came from the Arnold Arboretum, how about 'Harvard Gold?'” Let it be known! Like other plants in this blog it prospers with morning sun and afternoon shade. It is hard for me to estimate its height and width since we prune ours and sell them when small, and I've never grown one out in the garden. Chamaecyparis pisifera is known as the “Sawara false cypress” and it was introduced to Europe by Philipp von Siebold in 1860. One method to tell the C. pisifera species from C. obtusa is to look at the leaf underside: the white markings of pisifera form an x, and those of obtusa a y. But then most of us (nurserymen) can easily distinguish the two without close examination, even from a distance.

Cupressus macrocarpa at the Strybing Arboretum

Cupressus macrocarpa 'Greenstead Magnificent'

Cupressus macrocarpa is the “Monterey cypress” and the largest I have ever seen is growing at the Strybing Arboretum in San Francisco. It occurs in the wild in two small areas along the California coast which means that it tolerates salt spray, but then it is happy elsewhere too. It is marginally hardy for us, and it has succumbed in severe winters, or I should say its cultivars have croaked. 'Greenstead Magnificent' is a vigorous spreader with blue foliage. We like to stake ours up and prune them into neat pyramids. We've never been able to root it – maybe somebody has – but that brings up the question of what rootstock to use. I suppose other Cupressus species would work but I didn't have anything the first time I wanted to propagate, for someone sent me scions out of the blue. It was no major cerebral accomplishment to reason that Chamaecyparis nootkatensis crosses with Cupressus macrocarpa to produce x Cupressocyparis. So if I can use Thuja orientalis as understock for nootkatensis, then probably it would accept the macrocarpa as well. What do you know? – it does. I suspect – but haven't tried – that x Cupressocyparis and nootkatensis would work too. We also grow the golden juvenile Cupressus macrocarpa 'Wilma', and according to my records it was given to me by Brian Humphrey of England. It originated as a sport of 'Goldcrest', but often at Buchholz Nursery 'Wilma' can revert back to 'Goldcrest'. I suspect that millions of 'Wilma' are produced every year – I see them in grocery stores and other non-plant type of places. You'll often see them at Christmas time in a pot with a stupid red bow or ribbon around them. I even saw them for sale at a small Japanese florist kiosk in Tokyo.

Abies pindrow

Abies pindrow

I haven't grafted any Abies pindrow in about 15 years, but last winter I produced a few and now they are in pots in GH28. I love the species and I have some amazing specimens at Flora Farm. But apparently you didn't like pindrow because sales were never strong. I have seen the species in the western Himalaya and I have some photos of their amazing narrow crowns. Too bad I can't show them to you because they're still in slide form, and poor Seth is thousands of photos behind. The “experts” claim that pindrow is hardy to only USDA zone 8, or 10 degrees above zero, but I have a half-dozen of them that survived 0 degrees with 30 mph winds.* Sure, A. pindrow can get nailed by a late frost, but an established tree quickly recovers. I got my start from the nearby Otto Solburger estate, for the old Christmas tree grower also devoted a couple of acres for an exotic tree collection. I never met the man, but his wife seemed pleased that a youngster like me – I was 30 then – was interested in the trees, so she allowed me to cut scions. I have read that large conifer collections in Europe contain A. pindrow, and indeed it was introduced in 1837. The suggestion that the species requires “high humidity and rainfall” does not square with my experience. The pindrow name is derived from its Nepali name for the tree. E.H. Wilson claimed that the species name is derived from the Sanskrit word pind for “incense” and roo or row “to weep,” “from the numerous resinous tears found on the cones and other parts of the tree.” Hmm, where did I read that? And I don't think Wilson encountered A. pindrow in the wild.

*A specimen grows at the New York Botanical Garden – what's the hardiness zone there?

Pinus bungeana 'Great Wall'

The poor photo of Pinus bungeana above was taken at Shadow Nursery in Tennessee, but at least it shows a compact form of what he introduced as 'Great Wall'. I know no more than that, but Don kindly gave me a start.

Cryptomeria japonica 'Rasen'

I'll wrap up the blog with one more tree from GH28, Cryptomeria japonica 'Rasen'. It is an attractive cultivar as a small tree when you can admire its ringlets – the Japanese name means “barber pole” – and then if it has any landscape value beyond that, it's that it stays narrow as it soars skyward. In our conditions it can grow to 25' in just 10 years. As with all Cryptomerias, one need not use the word sugi, as in 'Sekkan sugi' or 'Rasen sugi', because sugi means the Cryptomeria tree itself, so sugi's use occurs in the Department of Redundancy's Department.

Visitors can spend a lot of time in GH28 because it contains many of the one-and-only in the collection. Every once in a while I'll discover a newbie that I didn't realize I had, then I must go back to my accession records to jog my memory about where I got it. One collects a lot of useless plants as well, but that is part of the process in my type of nursery. Before you know it, you've owned a nursery for 36 years and you are growing long in the tooth, but at least you didn't have to hold down a “real job.”

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