7 Step Pleached Lime Training with Tilia Cordata on a 10-Metre Wire Frame

Tilia cordata, the small-leaved lime, suits pleaching because repeated pruning shortens its internodes and its bark tolerates years of tying against galvanised wire without girdling. On a 10-metre frame, five to six stems at 1.8 to 2 metre centres will usually fill the run. The lowest training wire sits at 1.8 metres above grade, with the head zone carried upward to about 4 metres.

The frame takes the load before the trees do. Wire tensioned to around 30 to 40 kg between end posts keeps the horizontal lines from sagging once foliage and ties add weight in year two. End posts set 600 mm deep in concrete resist that pull, and intermediate posts at 3 metre intervals stop the wire bowing under the summer canopy.

Step one: build the frame first

The wire grid is built and tensioned before any rootball is dug in. Use 3.15 mm galvanised line wire at four heights: 1.8, 2.5, 3.2 and 4 metres. At each intended stem position, lash a vertical bamboo or hazel cane to the horizontal wires so the young leader has a rigid line to follow from planting day.

Set the verticals plumb with a 1200 mm spirit level. Pull a string line across the full 10 metres to check the horizontals. A 20 mm deviation at the post can disappear visually, while a 60 mm sag becomes obvious across the run once the leaves fill out.

The frame is the reference for every tie made over the next four years. Posts of 100 mm by 100 mm pressure-treated softwood last 12 to 15 years in the ground. Oak lasts about twice as long and costs roughly three times as much.

Step two: plant the whips at finished grade

Feathered maidens or two-year whips of Tilia cordata, 2 to 2.5 metres tall, go in at the marked centres. Set the graft union or root flare level with the surrounding soil. On heavy ground, planting 50 mm proud helps keep the collar clear of waterlogging, which can check lime growth for a season.

Backfill with loosened native soil so the roots push outward into the surrounding bed. Firm the soil in two stages, then water 15 to 20 litres per tree at planting in any weather.

Tie the leader loosely to its vertical cane with soft tree tie or rubber buckle ties. Keep wire away from bark. Accuracy matters here: a stem planted 150 mm off centre will sit out of line with the wire, and later pruning cannot straighten a trunk that has leaned toward its neighbour.

Step three: prune the cordons that build the head

The head develops through a cordon pruning routine repeated each dormant season. The previous year’s lateral extension is cut back to two or three buds, following the same short-spur logic used on trained fruit cordons.

As laterals extend, tie them along the horizontal wires. In winter, shorten them to thicken the framework. This repeated cut-and-tie cycle is what turns separate young trees into a continuous flat head.

During the first dormant pruning, remove side shoots below 1.8 metres flush with the stem. Above that line, retain shoots growing toward the wire plane and tie them in. Remove shoots that push forward or backward out of the plane.

By the third winter, the head should read as a flat curtain of short spurs about 300 to 400 mm deep. The clear stem below remains clean, and the trained zone carries the density.

Make the main cuts in late winter, before March bud movement in most temperate zones. Lime can weep sap from large late-spring wounds, so cuts thicker than 15 mm are best made during dormancy.

Use bypass secateurs for this structural work. A hedge trimmer has no place in spur pruning because each cut needs to land cleanly at a bud. Torn stubs invite dieback across the face of the trained head.

Step four: loosen the ties each year

Check and loosen every tie annually. A stem tied at 30 mm can reach 45 to 50 mm within two seasons, and a static tie cuts a permanent ring into the bark.

Step five: trim the summer face lightly

Mid-summer is when the trained box gets its mechanical cut. Once the framework is established, usually by year three or four, run a hedge trimmer lightly over the foliage curtain in July. The cut tidies soft extension growth and encourages denser budding behind the trimmed face.

A cordless trimmer with a 500 mm blade suits lime foliage. A tooth gap around 20 mm is useful on soft growth. Smaller gaps tend to clog.

Use the top horizontal wire as the visual reference and cut to a flat plane. Take 50 to 80 mm of the season’s extension. Cutting into two-year wood removes spur buds that provide next year’s density and leaves bare patches that can take two seasons to refill.

A second light pass in late August catches regrowth before it lignifies and keeps the winter silhouette crisp. Between the two summer cuts, the face should keep a slightly soft outline. The dormant secateur work later restores the precise rectangle.

Step six: feed the strip that carries the work

A pleached lime keeps producing extension growth that is removed twice a year, so the root zone needs steady moisture and slow feeding. Lay a 70 mm mulch of well-rotted bark or garden compost in a 1 metre band along the run, keeping it 50 mm clear of the stems.

Tilia cordata prefers soil in the pH 6.5 to 7.5 band. Acidic compost mixes pull the root zone outside that range and weaken the growth pattern needed for pleaching.

Nitrogen supports the extension growth that the routine depends on. Apply a balanced slow-release feed in spring at around 70 g per square metre.

On free-draining sandy sites, water through the first two summers. A drought-stressed stem aborts the soft growth needed for the July trim, and the box thins from the inside. Established runs after year four usually cope on their own except during extended dry spells.

Step seven: reduce the frame and keep the plane

By the fourth or fifth year, the frame can begin coming out post by post once the trunks stand without help and the head keeps its shape. Many growers remove the vertical canes first and leave the horizontal wires for another two or three years, because the trained head continues to push forward growth after the clear stem has stiffened.

Long-term care settles into two summer trims with a hedge trimmer, one dormant spur pruning with secateurs, and an annual tie check wherever wire remains. Stem girth can increase 10 to 15 mm a year on a vigorous site. Even after the frame is removed, slight scarring may remain where ties once sat, then fade over five to six seasons.

The spur systems also build up with age and need thinning every third winter to keep the curtain from moving forward off the original plane. A 10-metre run trained this way reaches its intended proportions around year six and then holds them with about four hours of work annually. The only trace left by the removed frame is the older scar line under the bark.