It seems as though every article I read about pleached trees includes the nugget of information that the word comes from the French word plechier or plessier, meaning to plait or weave. Gormlessly, I accepted this at face value, despite having grown up in then French-speaking Brussels; despite having spoken French rather well at one point; despite having plaited my hair as a schoolgirl and discussed this – in tedious detail, as one did – in French with my francophone friends; despite my never ever having encountered either variant of the word before. Someone, somewhere, made this up (or dug it out of an obscure French equivalent of Chaucer), and it has been repeated, unquestioningly, ever since. The correct term is ‘palissé’ or ‘en espalier’. So there.*
Whatever size trees you start with, you will first need to make your structure.
If you are starting with young trees that you will train from scratch, you need tall posts set in concrete at regular intervals (5m apart or thereabouts) with tensioned wire making up the horizontal bars between them (four or five bars is usual). Later this year in the courtyard garden I will be doing this too, with seven crab apple ‘Red Sentinel’ that I had to buy young (oh the satisfaction of ordering something on the right rootstock so that its ultimate size will be just right for my purposes). I have heeled them in beside the garage and will train them myself because I am looking for the lowest bar of the pleached branches to start lower than is usual with nursery supplied trees. And because it is much much cheaper. I will teach myself how to do this and post about it in due course.
This post however is about how to treat mature trees which have already been trained individually in the nursery: how to create a structure that links them together; and how to train them to it.
We planted six small leaved limes (Tilia cordata) in April 2014. By rights we should have done it a little earlier in the year (the trees were just starting to come into leaf), but although these were field grown trees they were dug up one day and transported to my garden the next, and they were to receive the very best of care, so we risked it. Their planting holes were large, the backfilled soil mixed with generous amounts of organic matter, and their rootballs sprinkled with liberal quantities of root growth enhancing mycorrhizal fungi (Root Grow, I SWEAR by it). They were tethered against windrock by an underground guying system (the excellent Arborguy from GreenBlueUrban), which means we didn’t have to have unsightly supporting posts, and each tree had a circle of perforated drainage pipe looped around its rootball with the end sticking up out of the ground, so that I could water them copiously (but only every now and then).
With a lot of hard work, we got them into position. I will not dwell on how unpopular my insistence that the trunks line up with the distant window breaks made me, nor how no one, myself included, made the leap of logic that suggested that a telegraph pole would indeed have an underground cable leading to it, which we promptly dug through. Once in position, I proceeded to do absolutely nothing to them (except water them and keep them weed free) for the next year. Mainly because I thought that they needed time to settle in before I started hacking them about, but in part because I didn’t really have a clue what to do next.
They passed an apparently happy summer (see photo above), coming into leaf and putting on lots of new growth while I bided my time and googled. Monty Don had what seemed to me to be sound advice, and equipped with my magnificent tripod ladder from Jake Hobson, my trusty Felco secateurs, a ball of twine and more bamboo canes than I imagined possible, I set to work in February 2015 to link these six disparate trees into a coherent whole.
Tip: wrap up warmly and wear wraparound glasses – being poked in the eye while balancing up a ladder in a howling gale is best avoided. Also, cut the twine into lengths (short bits of 35cm and longer bits of 80cm) while still in the warmth of the house, and stuff the different lengths into different pockets before you go up the ladder.
I found it was best to split the job into two parts: creating the new structure first and only once that was complete tying the branches onto the structure. My trees each had four bars of bamboo to which they had already been trained, so the first thing I did was to run new bamboo canes across the gap between the trees, weaving the canes in between the bamboo uprights and the trunks of the trees, and tying them securely into place to the existing bamboo bars with twine in at least four points along their length.
Once I had a solid – if slightly wavy – line of canes along each of the four bars, I then extended the structure out at either end with more canes, one end tied into the bamboo structure, the other reaching out to the point I wished to grow the foliage (above but abutting the datum).
Because the shape I am going for is a sort of shoebox on stilts, I want to train the branches of the two end trees to form right angles and meet in the middle. I therefore connected the two rows of trees with four horizontal canes (which I also braced with verticals in the corners for strength). By now the trees had more bamboo in them than they did tree (and over a week had passed), but I could finally start tying the branches to my bamboo structure.
Although the trees were quite twiggy and it had been fiddly to get the bamboo canes in place, until this point I had restricted myself to only pruning out the deadwood. One never knows when a branch will come in handy, and I learned that small leaved lime is amazingly bendy, which, it dawned on me, explains its popularity for this purpose. (I will have to be a lot more gentle with the more brittle crab apples when I come to train them.)
I tied in whatever I could to the horizontal bars, and then marshaled my quailing resolve and pruned out everything that was not in the right place for the shape I wanted, some branches back to 4-6″ or so, some right back to the branch bark collar with the trunk or main stems. I removed most of the new growth, as illustrated in the above photo showing the pruned back row and the unpruned front row (I started with the least visible bit until I got my courage up). The photo above also shows how we really should have thought at the outset about placing the six trees according to their straightness of stem, and hidden the one at the front on the left which has a backwards lean to it in a far less prominent position. I have built the structure to compensate, but I will have quite a job to train the bushy new growth out so that the vertical face of the ‘green box’ appears straight.
The two photographs above are before and after. And although I suspect that I might not have been ruthless enough, I will be very relieved come Spring to see them come into leaf.
The above photograph shows the end result. I am very pleased with it, but looking at it now I think I will have to get back up my ladder and lop the tops of the vertical bamboo canes that break the lovely horizontal lines. The two orange bags hanging from the branches are mesh bags that some of my Peter Nyssen bulbs arrived in (see? I knew they would come in useful), weighted with rocks and tied to joins that had an upwards arc to them, to try to bring them slowly into line with the horizontal. My husband finds them vaguely unsettling, reminiscent of a medieval display of the heads (or worse) of one’s enemies on spikes . I can’t see it myself, but there’s a novel idea for a show garden at Chelsea if ever I heard one.