Friday, February 14, 2020

...Another Winter's Grafting Summary

This past week we wrapped up (pun intended) our winter grafting season. One might wonder what keeps old Buchholz propelled with plant production, as if I don't realize and accept the fact that I'll be too old and feeble to care about – or take care of – the young starts that we created in the past few months. Is it just stupid habitual inertia, perhaps combined with a lack of viable exit plan, that keeps me propagating plants, or is it the only way that this old geezer can have fun? The answer is: yes to the above, at least somewhat, but understand that you'll never be invited to rest with me in my coffin because I plan on getting some work done there too.

Chamaecyparis obtusa 'Gitte'

Chamaecyparis obtusa 'Gitte'

I decide everything with our propagation department: what and how many to graft and/or root. Sometimes – like with the Chamaecyparis obtusas – we produce them both ways. The graft, with its two or three-year-old rootstock is a faster method to get a saleable plant, which is especially valuable for the miniatures. However, with some cultivars, such as the dwarf Chamaecyparis obtusa 'Gitte', the extra boost from its Thuja occidentalis 'Smaragd' rootstock, especially when grafted on a standard, can push undesirable wild growth on the graft. Last week a Dutch nurseryman (Mr. S.) saw a row here of 5-year-old 'Gitte' on standards, and he asked if the cultivar was indeed 'Gitte'. I replied that it was, but he observed that it “doesn't look that way at home.” He should know because the selection came from his nursery and was named for his granddaughter...if I understood him correctly. Since we are done with this season's propagation I will send someone with shears and instructions to prune mine into more-tight globes.

Chamaecyparis nootkatensis in the wild

I have produced Chamaecyparis nootkatensis – now named Xanthocyparis nootkatensis – by both grafting onto Thuja orientalis – now named Platycladus orientalis – and by rooted cuttings. Cultivars of the “Weeping Alaskan cedar” are easily rooted and graft “takes” are usually high. I estimate that my small nursery has produced about a quarter million nootkatensis grafts over the course of my career, because for about three decades we supplied lining-out plants for many of America's wholesale growers, some who would order as many as 800 per year. So, I've made a ton of profit with the species, but...a less-than-pleasant aside is that the scions – most of which I have personally cut, and also the thousands that I have personally grafted – smell like a high-schooler's gym socks soaked in cat piss.

Chamaecyparis nootkatensis 'Green Arrow' 

I was the nurseryman who introduced Chamaecyparis nootkatensis 'Green Arrow' into the trade, when the discoverer and namer Gordon Bentham of Victoria, B.C. told me about the fantastic tree a year before he died. The nursery where he worked had gone bankrupt and the few plants were being liquidated, so I'm certain that 'Green Arrow' would have been lost to horticulture if I hadn't lucked onto them in the early 1980's. I don't produce many anymore because everyone else does, and about ten years ago I saw about 100 for sale in a Seattle-area garden center that looked great – supplied by a grower I never heard of – and they were retailing for less than my wholesale price. The cultivar is even grown in Europe now, and in The Hillier Manual of Trees and Shrubs (2014) it is listed as “A very narrow, medium-sized tree with pendulous branches held close to the trunk. Foliage dark green.” Well, on a foggy Olde English day, and from a distance, you might consider the foliage to be dark green, but on close inspection it is actually gray-blue-green, as evidenced by the photo above.

Chamaecyparis nootkatensis 'Van den Akker'

A cultivar, more green and not listed by Hillier, is C. nootkatensis 'Van den Akker' which was introduced in Washington state. It might have been present before 'Green Arrow' but it really wasn't in the trade, as in nurseries producing it and shipping it around the country. 'Van den Akker' was found in the wild by someone who gave it to the Dutch landscaper who named it for himself. He produced enough to supply his landscape firm, and I have discovered them in various western Washington plantings where some probably exceed 50' tall. Its narrow habit is reminiscent of 'Green Arrow' except that 'Van den Akker' tends to form additional vertical shoots from the base, making an old specimen look like a small forest. All of the nootkatensis cultivars are compatible with Thuja orientalis, but for an unknown reason 'Van den Akker' does not perform uniformly as a graft, so all of our production is from rooted cuttings.

Taiwania cryptomerioides

We had a handful of Cryptomeria japonica 'Yoshino' in pots which we rooted two years ago and I instructed our grafter to put 'Dense Jade' on them. All Cryptomeria cultivars root fairly easily for us except for 'Dense Jade'. So the rootstocks were all used up and as I drove home that night I let out a groan, suddenly remembering that I wanted to try grafting Taiwania cryptomerioides onto the Cryptomeria. The two genera kind of look alike, don't they? The idea wasn't originally mine, rather I read about the combination in Brian Humphrey's new book The Bench Grafter's Handbook, in which he comments, “Relatively easy in temperatures of 10-15 C.” Humphrey's book features a chapter called Grafting Table List, where he offers the 1) preferred rootstock choice, 2) also possible, 3) least successful and 4) suggestion, not proven. I predict that The Bench Grafter's Handbook will become the standard text for propagation classes in horticultural institutions worldwide. I wish I had another 20-30 years to test his theories, but the book came to me only last year when I'm nearly ready to put my knife away for the final time. I won't reveal any more of Humphrey's secrets, such as what rootstock to use to graft Carpinus fangiana for example – you'll have to purchase the book yourself. CRC Press, IBN 13: 978-1-138-04622-1.

Ginkgo biloba 'Chi Chi'

We root Ginkgo biloba 'Chi Chi' under mist in the summer, and it makes an attractive, compact container or field plant. A word of warning, if you live in Oregon anyway, is that the Oregon pocket gopher loves to eat Ginkgo roots and can kill a tree. One year we even had scale on the Ginkgo trees in our greenhouse, and I found the best way to manage that pest was to burn the tops. So much for the old adage that the unknowing “experts” like to repeat, that “Ginkgo is free from disease and pests.” It reminds me of the TV insurance commercial where the wise old agent says, “At Farmers we know a thing or two because we've seen a thing or two.”

Ginkgo biloba 'Snow Cloud'

Anyway we also use the 'Chi Chi' as rootstock for our other dwarf cultivars such as 'Mariken', 'Spring Grove', 'Troll' and 'Gnome'. Even fast upright selections, such as the narrow pillar 'Grindstone', exhibits exuberant growth on the more dwarf rootstock, as if it makes no difference while sending up 30-36” shoots in the greenhouse. I was also pleased this winter to graft 70 Ginkgo 'Snow Cloud', a new variegated cultivar that does not revert. I ravaged my stock tree to get that many scions, but it was worth it because everyone who sees 'Snow Cloud' wants it.

Pinus contorta 'Chief Joseph'

Usually the first conifer we graft is Pinus contorta 'Chief Joseph'. In the past I would begin in mid October to mid November when the needles were still greenish, the idea being that it was best to graft before they turned to brilliant gold. Two winters ago we didn't get around to grafting until the first of December and we achieved about 60%, our best ever, and believe me, the needles were quite gold then. The first of December is when we grafted this past winter. J, my ace grafter, frets about the low percentage of success and seems to take it personally. She suggested that we use a different rootstock, like Pinus sylvestris instead of contorta, but I replied that we used to graft on sylvestris and our results were even worse back then. She continued to stew about it, so I emphatically quieted her by saying I'm very happy if we can get 50%; we'll sell them for more money, so don't worry about it. What she doesn't know is that all producers of 'Chief Joseph', that I know, say, “Wow – 50% – that's pretty good!”

Calocedrus decurrens 'Berrima Gold'

One more word about 'Chief Joseph' is that you probably do not want to grow them commercially in the field, and then harvest (dig) them in the winter. I only grow in containers now, after losing way too many in the past. If I was to dig one from the ground I would probably choose the end of August to do so. Another plant where most die from winter harvest is Calocedrus decurrens 'Berrima Gold', and since it is yellow all year long, I would have my doubts about August digging. One retail nursery owner sighed when she saw my large crop of 'Berrima Gold' in containers and said that she gave up on it “because they always die.” She related that XYZ wholesale nursery refused to give her credit for the dead trees he provided because they all “looked great” when shipped. I convinced her to never buy a B&B 'Berrima Gold', but that when they're grown in containers there should never be a problem. By the way, neither of us shed tears when XYZ Nursery went bankrupt a few years ago.

Cornus kousa 'Summer Fun'

Magnolia 'Manchu Fan'

Scions are already beginning to push on our December grafts of Cornus and Magnolia that were placed on the hot callus pipe. The temperature is kept at 70F and we keep the graft union just above the hot-water for three weeks. If kept on longer, one runs the risk of over callusing, though I've never experimented to see what kind of problem might result. The definition of a plant nursery is a place where you fool nature, or at least hurry her along, and that's what the hot pipe does. Without it the side grafts would wait until late April-May to produce new growth. For easy to grow hardwoods, such as Ginkgo, we don't bother with the time-consuming hot callus method because we achieve 98% success anyway.

How do I decide how many of a certain plant to graft? Well, it's been 40 years of making plenty of mistakes with too many or too few, and only occasionally the perfect amount. It's a moving target anyway where plant sales can be hot for ten years, then suddenly fall off. One key to success is to grow a lot of different things, but none of them in great numbers. Also, I think it's best to only propagate plants that do not have a short shelf life, i.e. only plants that you don't mind keeping and potting into larger sizes. The neighbor's nursery went under because the bulk of his crops were cheap, easy-to-produce products like Euonymus (by the many thousands), Alberta spruce, roses etc., where if they don't sell you wind up dumping the crop. I'll use tomatoes as an example: Most retail nurseries sell them in 4” pots for a dollar or two, and maybe a few in one-gallon cans for, say three dollars. If they don't sell you don't pot them into a 20” wood box which costs you over $20, because there's absolutely no market for an expensive tomato plant. If your Japanese maples don't sell at a relatively small size when you have a thousand, you move the remainder into larger pots, take good care of them and sell them the following year, or the following...and maybe after ten years you have only a few $200 trees left and your market is happy to find the few at a large size. Anyway, that system has worked for me, except that in good times the cheap Euonymus grower makes more money than I. I guess the grower should have faith in his crops, that they will eventually reward him.

Cedrus atlantica 'Glauca'
Cedrus atlantica 'Glauca Pendula'

Cedrus deodara

Most of the blog readership would assume that I'm about 39 years old, but in fact it was 44 years ago that I grafted my first trees, beginning at a nursery where I worked. My boss was always complaining that he couldn't get enough grafted plants from the Dutchman's nursery who was the only producer back then. I suggested that we skip the Dutchman and do our own. That winter my boss provided me with 12,000 Cedrus deodara in pots, and I (self-taught) grafted the bulk of them with Cedrus atlantica 'Glauca' and a few with 'Glauca Pendula'. Cedrus are pretty easy to do and the take (with beginner's luck) was over 90%. I noticed in a propagating book that one was advised to heel in the graft union with sawdust and keep the tops moist so the scion wouldn't dry out. Besides, the bench had bottom heat, and the whole environment was a tropical paradise in the Oregon winter. But oops! – the conditions were perfect for the gray mold to develop on the puffs of new growth. I was able to prune and spray my way out of trouble, plus I discontinued with the top mist, so the end result wasn't too bad. But ever since that first experience with grafting I find myself constantly worrying.

No comments:

Post a Comment