Friday, November 21, 2014

Winter Grafting

Winter at Buchholz Nursery

Snow. Freezing rain. Here we go again, except it's earlier than before. We pump water from the Tualatin River in the summer to keep our pond full to irrigate the nursery, and fortunately we were able to get our pumps out in time so that they didn't wash down the river. Greenhouse pilot lights are on and thermostats are set. Irrigation lines are drained. Antifreeze is in all of the vehicles. Check. What am I forgetting? I used to employ a kid who was old enough to be a man, but wasn't, and he once told me that I "worried too much." I countered that "you don't worry enough." Eventually he was fired and we received addition by subtraction. But anyway, yes, I do worry a lot.

The employees are holed up in the greenhouses, pruning, staking and preparing rootstock for this winter's grafting. I've done it all myself, thousands of times, and who wouldn't rather be inside on a cold crummy day? The Golden Rule applies for all employers with their workers: Do unto others as you would have them do unto you. I have been the grunt before with dumb-shit bosses, so I know that a decent employer makes all the difference.

I'm also inside, monitoring the rootstock preparation. There are thousands to prune, and there's a best way – the fastest way – to get the job done. When I started my nursery I was also working full-time at another, plus an hour's drive each way. I was always behind, and I felt that I had to complete many tasks before I could go to bed. All of the rootstocks are different, and a Pinus sylvestris is usually easier to clean than a Picea abies. Maples are a cinch, as we now use a gas-powered weed trimmer, and 25 thousand palmatums last summer were pruned in under two hours.

Pinus contorta 'Chief Joseph'

So what's going to be grafted with the Pinus sylvestris rootstock? For sure we'll graft three cultivars of Pinus contorta: 'Chief Joseph', 'Taylor's Sunburst' and 'Frisian Gold'. We've never had too many of any of these, as our grafting percentage is not very good, and other propagators can attest to that. If you get only 30% on your grafting, then you can't sell them as liners, unless you charge $20 each. 'Chief Joseph' was discovered by Doug Will of Sandy, Oregon while he was hunting in the Wallowa Mountains of Oregon's northeast corner, an area often likened to Switzerland. From his campsite he could see something yellow in the distance, which he thought was a yellow bucket. Not wanting somebody's trash to interfere with his forest experience, he set out to retrieve the garbage, but instead discovered that he had discovered a golden pine. He dug it out of the hard ground and brought it to his small nursery...and eventually propagated it. Small retail one-gallon pots go for as much as $60, and for the avid gardener the cost is worth every cent. 'Chief Joseph' is a member of the Pinus contorta ssp. latifolia which is native from the Yukon to southern Colorado in the Rockies. It was a species found useful to Native Americans of that region, and is commonly known as "Lodgepole Pine," as they constructed their tee-pees with the straight young poles.

Pinus contorta 'Taylor's Sunburst'

Pinus contorta 'Taylor's Sunburst' is also from the sub-species latifolia, and was discovered by Dr. Alan Taylor, who found it in the Colorado Rockies. The needle color is basically green for most of the year, but in May the new growth is butter-yellow, and it is often adorned with tiny red first-year cones. The tree is an upright, somewhat irregular conifer, but a specimen seen in its glorious spring moment is a sight never to be forgotten. It might be wise to plant 'Chief Joseph' and 'Taylor's Sunburst' next to each other, for one will look great in winter and the other in spring.

Pinus contorta 'Frisian Gold' at Jeddeloh Nursery

Pinus contorta 'Frisian Gold' is a dwarf compact cultivar with bright golden foliage, but if grown in shade the needles will be yellowish-green. It was discovered at the Jeddeloh Nursery in Germany about 1962, and in the photo above you can see the green of the original tree along with its golden mutation. I'm not sure why it was given its cultivar name, but Frisia is homeland of the Frisians, a Germanic people whose language is related to the English language, and who occupy the northern, coastal region of the Netherlands, Germany and Denmark. Naturally, the bulk of the German people refer to Frisians as dim-witted, and there are some funny jokes* about them, like we have for people living in the Ozarks. 'Frisian Gold' belongs to the subspecies of contorta called bolanderi, the "Mendocino Shore Pine," which is restricted to the Mendocino county in California. It was named for Henry Nicholas Bolander (1831-1897), a German-born botanist who resided in San Francisco, and today we have 37 species of flowering plants which bear his name. One example is our west coast USA silver sagebrush, Artemisia cana ssp. bolanderi.

*Question: Why do Frisians have windshield wipers on the inside of their cars?
 Answer: Because they bumble their lips and spit when they drive.

Pinus contorta 'Spaan's Dwarf'

Ok, I guess we'll graft a few of the fourth P. contorta cultivar, 'Spaan's Dwarf', a dwarf irregular bush with an open canopy, a tree which often reminds me of a coral structure. It was named by – or for – a nurseryman of Dutch descent who found it in Washington state. A ten-year-old tree will grow to about two feet tall by three feet wide, and it makes a nice addition to a miniature or rock garden.

Picea abies 'Acro-yellow'

Picea abies 'Vermont Gold'

Picea abies 'Vermont Gold'

On the Picea abies (Norway Spruce) rootstock we'll graft a couple of golden selections from Greg Williams in Vermont, Picea abies 'Acro-yellow' and Picea abies 'Vermont Gold'. The 'Vermont Gold' displays a dense spreading form, and will grow to about one foot tall by two feet wide in ten years. We have even staked 'Vermont Gold' and these grow into dense pyramids. In Oregon's humidless summers it is best sited with afternoon shade, but like with many golden plants, too much shade will result in a green plant. Picea abies 'Acro-yellow' is a yellow-needled upright that bears numerous cones, as the mother tree was the old cultivar Picea abies 'Acrocona'. A number of these seedlings were raised, including one called (at least temporarily) 'Accronz Odd Seedling'. Greg Williams dismisses many of his selections with "I was just foolin' around," but we have some very useful plants such as Pinus strobus 'Mini Twists,' a dwarf pine with curvy needles.

Chamaecyparis nootkatensis 'Green Arrow'

Each winter we root Thuja orientalis, and two years later they are ready as understock for our Chamaecyparis nootkatensis* cultivars. We still produce 'Green Arrow', only not in the great numbers as before, as most used to be sold as liners to nurseries now bankrupt or still floundering. 'Green Arrow' was discovered by the late Gordon Bentham who worked at the Den Allen Nursery in Victoria, B.C. I visited the company shortly after Mr. Bentham's death, and found that they too were bankrupt. I bought the handful of 'Green Arrow' and brought them back to Oregon and eventually introduced them into the trade. I suppose if I hadn't taken them the cultivar would have been lost to horticulture.

*Or Xanthocyparis nootkatensis as some would have it. According to Hillier, "A genus erected to accommodate the recently discovered X. vietnamensis and closely related X. nootkatensis...but the correct placement of these two species is still the topic of taxonomic debate."

Chamaecyparis nootkatensis 'Sparkling Arrow'

Of course we'll graft more Chamaecyparis nootkatensis 'Sparkling Arrow', a variegated selection discovered at Buchholz Nursery as a branch mutation fifteen years ago. It took a long time to grow quantities because I wanted only scions of vigorous shoots so that the offspring would resemble the narrow growth habit of the 'Green Arrow' mother plant. I'm aware of a nursery that grafted all the scionwood possible from their one stock tree, and I wonder if they'll dilute the narrowness of 'Sparkling Arrow' with wider trees. Just buy your plants from me for heaven's sake.

Chamaecyparis nootkatensis 'Nidifera'

We'll also produce Chamaecyparis nootkatensis 'Nidifera', a seedling selection from Italy in the 1880's. My start came from the Bedgebury Pinetum in southern England and I wonder why you never see it offered in retail garden centers – except a few of those who buy from me. It is a beautiful plant with its lacy blue foliage and nodding branch tips, and when customers walk past one they're always impressed and usually ask, "What is it?"

Cupressus macrocarpa 'Greenstead Magnificent'

Cupressus cashmeriana

It will perhaps surprise you that we use Thuja orientalis as rootstock for Cupressus macrocarpa 'Greenstead Magnificent', but they make a perfect match. When I began my career I researched all possible compatible rootstocks for plants I knew I could sell. I reasoned that since Cupressus macrocarpa and Chamaecyparis nootkatensis had crossed to create x Cupressocyparis leylandii (now known as Cuprocyparis leylandii), and if you can successfully graft nootkatensis on T. orientalis, then why not a Cupressus macrocarpa cultivar? One of my strangest discoveries was that Cupressus cashmeriana is perfectly compatible with Thuja occidentalis 'Smaragd' as rootstock, but not so with Thuja occidentalis 'Pyramidalis' Isn't horticulture fun?

Fagus sylvatica 'Aurea Pendula'

Cornus kousa 'Ohkan'

It's not just conifers that we graft in winter, but also cultivars of Fagus, Ginkgo, Acer, Cornus etc. The harder woods such as Fagus and Cornus will go on our hot callus pipes which are set at 70 degrees F. The pipe is a tube of heated water that the graft union is set upon for three weeks. Plants that can be difficult to propagate in a regular greenhouse setting will do much better with the direct heat. If left on too long the graft will over-callus and that can lead to problems. Plants such as Acer – the stripe-barks – seem to be too soft to handle the direct heat, although I know that Guy Meacham at Plantmad Nursery can propagate many soft woods on his callus pipes. The Ginkgo doesn't need the pipe because we achieve virtually 100% without it, so why bother with the extra labor to set them out?

Ginkgo biloba 'Weeping Wonder'

And speaking of Ginkgo, we'll produce a few 'Weeping Wonder', even though it doesn't really weep, nor is it a wonder. It's a novelty though, as it displays a number of different leaf shapes and sizes on the same bush, from tightly-rolled tubes to normal full-sized leaves. Its autumn color is as good as any Ginkgo, but after the leaves fall, you then realize you have a female with stinky fruits. 'Weeping Wonder' is a great name, but at best it is an irregular spreader. In ten years it will grow to four feet tall by four feet wide.

Ginkgo biloba 'Mariken'

Ginkgo biloba 'Mariken'

Ginkgo biloba 'Troll'

Ginkgo biloba 'Spring Grove'
Ginkgo biloba 'Munchkin'

The bulk of our rootstocks (which we root ourselves) goes for the dwarf cultivars like 'Mariken', 'Troll', 'Spring Grove', 'Munchkin' and 'Chase Manhattan'. The first three are similar, and you must be careful to not mix them, especially when they are young. 'Chase Manhattan' is more dwarf than the first three, with 'Munchkin' being the most dwarf of all. So far all of these cultivars appear to be male, so they won't produce the messy fruits; but I say "so far," because sometimes male clones – like 'Autumn Gold' – can change their sex, or become bisexual.

Ginkgo biloba 'Jade Butterflies'

Ginkgo biloba 'Jade Butterflies' still sells well. It originated at the late Duncan and Davies Nursery of New Zealand and was described by them as a "strong pyramidal tree," but in my experience it can assume many forms. True, the photograph above is – or was – pyramidal, but I sold the 15' specimen because it was eventually to be crowded out by two Acer palmatum cultivars, when the original planting seemed sufficient for time immemorial. In the luxurious New Zealand climate I don't doubt that 'Jade Butterflies' is strongly pyramidal, but I've seen just as many with a bush form. Perhaps it's a factor of the origin of the scionwood, but I know that nurserymen, including myself, fight a tough battle with many Ginkgo cultivars to get them to grow the way we we similarly do with our children. I had a chuckle when a mail-order customer purchased 'Jade Butterflies' from me, then later described the cultivar as possessing "leaves larger than the type," in the shape of a green butterfly. He got the shape right, but the leaf-size is actually smaller than the type when you look at a specimen in the garden. This customer was observing three-year-old plants grown in my happy greenhouse environment, where you can easily be fooled with plant vigor. 'Jade Butterflies' is the correct name, in spite of many growers using a 'Jade Butterfly' name.

Acer pectinatum 'Mozart'

Acer pectinatum 'Mozart'

This past summer we rooted twigs of Acer pectinatum 'Mozart', but I look forward to grafting some this winter. They will be grafted on Acer davidii rootstock, and the green understock will perhaps add extra vigor, for 'Mozart' is somewhat of a freak with its red trunk with white striations. The same is true with Acer x conspicuum 'Phoenix', and in my (limited) experience 'Phoenix' from rooted cuttings or via tissue culture will not be as strong compared to a grafted tree. Some growers list 'Mozart' as an Acer x conspicuum, but I have nothing to add to the discussion. Hillier lists it as a pectinatum species, and continues, "Raised from seed wild-collected by Peter Vanlaerhoven." I don't see how that is possible with the x conspicuum parents being Acer davidii from China, and Acer pensylvanicum coming from eastern North America. Where is this wild patch that Peter V. supposedly collected from? The only reason why any of this matters is to help determine the hybrid's hardiness, but then trial will be the final answer anyway. All I know is that Dutch nurseries are cranking out thousands of 'Mozart' by rooted cuttings, and they're being shipped all over Europe.

Acer rubrum 'Vanity'

Acer pentaphyllum

Acer pentaphyllum

Acer griseum

Most of the newer, improved cultivars of Acer rubrum are patented, so that leaves me out...but then why do I have rubrum rootstock? Because we'll graft an unpatented variegated rubrum called 'Vanity'. This cultivar grows into a medium-sized bush if left on its own, but is quite colorful – some would say garish and vain – with its pink and white spring-summer foliage. Also we use rubrum rootstock to graft Acer pentaphyllum, even though the two species are in different sections (Rubra and Pentaphylla). Even Acer griseum is compatible with Acer rubrum, and griseum is in the section Trifoliata.

Stewartia monadelpha

Stewartia monadelpha 'Pendula'

Stewartia monadelpha 'Pendula' can't be a valid cultivar name, but I received it from Japan as such, and in any case we'll graft some more this winter. In late spring the flowers are small and white, but the delicate-looking green leaves are attractive. Autumn color is a strong orange-to-red, and then in winter the cinnamon-colored bark is ornamentally evident. 'Pendula' forms a spreading bush with arching branches, to about 6' tall by 5' wide in ten years from a graft. We train a leader to 6' tall, and then let it weep from there; but as a young plant at Buchholz Nursery the pendulous trait is not apparent until it ages to about eight years. This selection will likely not become commonplace, as the Stewartia genus is notoriously difficult to propagate – the cultivars anyway – and I sure would like to hear from someone with better results, even if you just claim so to brag.

Halfway through grafting I usually panic, and wonder if we'll ever get through with it, just as I worry about summer propagation. At the same time, I often wonder if we should skip an entire year's propagation because we already have so many young plants in the pipeline. Since I need a guiding hand, I think I'll divine the path with my crystal ball.

"Keep propagating, Talon, the world needs more of your plants."

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