Pleach a Carpinus Betulus Screen on 3 Wire Tiers with Gripple Tensioners

Three wires, spaced at 1.8m, 2.1m and 2.4m off the ground, is the standard rig for a stilted hornbeam screen where you want a clear trunk zone below and a solid green rectangle above. The clear stem sits between 1.5m and 1.8m depending on whether you are screening a first-floor window or just a fence line. Carpinus betulus is the right species for this because it holds russet marcescent leaf through winter and takes hard repeat cutting without sulking, which beech does too but beech browns off uglier on chalk soils.

Buy the whips as feathered maidens or two-year selected pleaching stock, 200 to 250cm tall, from a nursery that sells them by the pleached-frame batch. Deepdale and Practicality Brown both grade stems for straightness, and it matters: a whip with a kink at 40cm sets the whole panel crooked and you never fully train it out. Plant at 45cm to 60cm centres along the run. Closer than 45cm and the trunks compete and thin; wider than 60cm and the horizontal tiers strain to close the gaps in year one.

Setting the posts and the wire before a single tree goes in

The frame goes up first. Timber not planted. Use 100mm square tanalised posts, or better, galvanised steel line posts if the run is over 8m, set 750mm into the ground on a concreted footing. End posts and any post over a 6m span need bracing back at 45 degrees or the wire tension pulls them inward within a season. A pleached run of ten trees on 60cm centres is 6m of active wire, and 2mm wire tensioned properly carries real load, enough to lean a poorly footed 2.4m post noticeably out of plumb.

Run 2mm galvanised or 2.5mm high-tensile line wire. The Gripple Plus No.2 tensioner takes 1.4mm to 2.2mm wire and does the job with a setting tool you turn until the wire sings at about a guitar-string B. Overtighten and you bow the intermediate posts; undertighten and the horizontal stems sag mid-span and the panel loses its flat face. Set each of the three tiers dead level with a long spirit level or a laser line, because the eye reads any droop across a horizontal screen instantly, far more than it reads it on a vertical.

Drill the intermediate posts and run the wire through, or use screw eyes rated for the load. On steel posts, wire clips. The whole rig should be finished and tensioned before planting so you are tying green stems to a fixed, true reference from day one.

The first winter cut sets the tiers

Plant bare-root between November and March while dormant. Once in, select the leader and cut back competing forward growth, then bend and tie the two lowest side shoots out horizontally along the bottom wire, one each direction. Soft ties. Use flexible tree tie or 6mm rubber-cored wire tie, never anything that girdles as the stem thickens. Check ties every spring and loosen any that are cutting in, because a hornbeam stem trained horizontally can put on 8mm to 12mm of girth in a strong year and a tight tie will ring-bark it inside two seasons.

Anything that will not reach the wire this year, shorten to two or three buds pointing the way you want next year’s extension shoot to grow. The leader continues up to the next tier. This is where a Silky pruning saw earns its place for the thicker leader cuts, clean pull-stroke cuts that heal fast, while a pair of Felco No.2 or No.6 secateurs handles everything under 20mm.

Repeat the same logic at each tier as the leader reaches it. By the end of the third winter you should have all three horizontals tied in on most trees, and the panel starts to read as one surface. The stems fuse where they cross between trees if you let two adjacent horizontals overlap and rub, which is optional; some growers graft the crossings deliberately for rigidity, most just let them thicken side by side.

Felco maintenance, because a dragging blade tears hornbeam

Hornbeam bark tears if your secateur blade is blunt or the anvil-gap is sloppy, and a torn cut on a horizontal stem is an entry point for coral spot. Strip the Felco down every few weeks in the cutting season: the blade comes off with the centre bolt, clean the sap gum off with a rag and a little WD-40, touch up the bevel with the Felco 903 diamond sharpener at the factory angle, and adjust the blade-to-anvil bolt so the blade just kisses the anvil without binding. A Felco No.2 that is properly set will slice a 15mm hornbeam whip without crushing it.

Summer pruning is where the flat face actually happens

Winter builds the frame. Summer builds the surface. From late June into August you cut the current season’s soft growth back to keep the face flat and force density, and this is the cut most people skimp on and then wonder why their screen looks whiskery rather than solid.

Go over the whole panel and shorten every outward-projecting shoot to two or three leaves from its base. On the faces, front and back, cut back to hold a flat plane roughly 20cm to 25cm thick. On the top, level it to the top wire until the trees have grown past it, then hold the height. Two passes across the summer, one in early July and one in late August, is better than one hard cut, because the second flush after the July cut is what thickens the face into something you cannot see through.

The seasonal hedge shaping logic here is identical to any formal hornbeam hedge, just applied to a raised panel on wires. Cut in dry weather so cut ends dry rather than sitting wet. Avoid the hardest cutting in a drought year when the tree cannot push a recovery flush. The clear stem below the bottom wire gets rubbed clean of any epicormic shoots as they appear, a thirty-second job with a thumbnail or the Silky if they have gone woody, and if you leave them a season they thicken into a mess that spoils the stilted look.

A neglected panel that has run to 40cm or 50cm of face growth can be brought back, because Carpinus breaks readily from old wood, but do the reduction over two winters, taking the back face hard one year and the front the next, so the tree is never fully stripped in a single season.

When you inherit an overgrown one

Renovating a pleached screen someone else let bolt is slower than starting fresh. Assess the wire first. Ten-year-old 2mm wire behind a heavy panel is often stretched or rust-thinned, and the Gripple tensioners may have reached the end of their travel, in which case you cut the wire out and re-run it before you touch the tree, working the new wire in behind the existing trained stems.

Then reduce the crown thickness back toward 25cm over two winters, use the Silky pruning saw for any crown lifting or removal of a stem that has died out mid-run, and re-tie any horizontals that have pulled off their wire. Hornbeam that has thrown vertical water shoots off the top tier gets those thinned to two or three good replacements and the rest removed at the base. The panel usually looks worse for a full growing season before the summer flush closes it back up.

What nobody tells you is how much the trunk spacing you inherited limits the recovery. Trees planted at 90cm centres will never close into the tight flat face that 50cm centres give, no matter how you cut, and at that point the honest question is whether you interplant new whips between the old trunks or accept a looser screen than the one you were hoping for.