9 Step Clematis Jackmanii Group Three Pruning Routine with Felco 2 Secateurs in March

Timing the late winter cut

Jackmanii belongs in pruning Group Three, the category the Royal Horticultural Society uses for clematis that bloom on growth made in the same year. Old stems can stay standing through winter, then in spring they channel energy into a dead, tangled upper structure. The flowering wood comes fresh from low buds, so the cut belongs at the dormant or barely stirring stage, across most of Britain from late February to mid March.

Getting the date wrong cuts both ways. Move in too soon and a late frost can finish off the buds you have just exposed, while leaving it until growth is well underway wastes the reserves the plant has already poured into stems you are about to take off. A useful marker is the swelling of the lowest pair of buds to about the size of a grain of rice.

Once green is visible at 20 to 30cm above soil level, the plant has begun moving sap and the wound can heal cleanly. The same timing logic applies to other current-season flowerers, from buddleia to autumn raspberries: last year’s framework comes away before the new season puts much energy into it.

Setting up the Felco 2

The Felco 2 is a bypass pruner, with a blade that passes the anvil in a scissor action. On green clematis stems, that matters. An anvil pruner bruises soft tissue and leaves a ragged edge that dries back.

Start with the blade. A Felco 2 that has worked through a season of woody growth often develops a rolled edge, easy to feel with a thumbnail. A few passes with the Felco 903 carbide sharpener at the factory bevel angle restores the edge in under a minute.

Then check the cushion stop and central bolt. If the blades wobble, tighten the nut by a quarter turn with the Felco keys until the action feels firm without stiffness.

Sap and dried plant matter also collect in the pivot. A rag and a drop of light oil clear the movement before the first stem is cut.

A clean, sharp Felco 2 should close once through a 15mm clematis stem with no twisting. Twisting tears bark and creates a wound that can invite clematis wilt, the fungal problem that can collapse whole shoots overnight. The finished cut should have a smooth, uncrushed face, and the cane should drop free in one piece.

The cuts, in working order

The routine below fits a single established Jackmanii grown up an obelisk or against a wall.

1. Clear the dead wood first. Run a hand up each stem from the base. Anything brittle, hollow, or snapping without a bend is dead, so cut it at ground level and pull it free of the support.

2. Find the lowest live bud pair on every remaining stem. These buds usually sit 15 to 45cm above the soil, paired opposite each other on the cane.

3. Take the strongest two or three stems back to a point just above a strong low bud pair, usually around 20 to 30cm from the ground. Set the Felco 2 so the cut sits 5mm above the buds and slopes away from them.

4. Cut the remaining weaker stems a little higher, to a bud pair at 30 to 45cm. The staggered heights place flowering wood at several levels and prevent a single dense skirt from forming.

5. Remove any stem thinner than 3mm entirely. It will make a weak shoot that flops and shades stronger growth below.

6. Untangle the cut stems from the support and from each other. Dead clematis growth can grip wire and trellis tightly, so loosen it by hand to avoid snapping the live buds already found.

7. Check each retained stem for signs of last year’s clematis wilt damage, such as a blackened section or sudden collapse point. Cut 5cm below any such mark, into clean white pith, and keep that material separate.

8. Tie the retained stems loosely to the lowest rungs of the support with soft jute twine, spacing them so the new growth has room to fan out. A figure-of-eight tie leaves slack for thickening.

9. Mulch the crown with 5cm of garden compost, keeping the compost a hand’s width away from the cut stem bases so the collar does not stay wet.

A mature Jackmanii treated this way loses most of its visible height and can look alarmingly bare. By June it will have climbed past the cut points, carrying the purple flowers it is grown for on every new shoot.

What a hard cut leaves behind

The first time you do this to a vigorous plant, the result looks like a mistake. A clematis that filled a 1.8m obelisk last summer can come down to a knee-high cluster of stubs, and you will have a barrowload of tangled growth on the ground. Most of what you remove is dead or spent, with only the lowest stretch of each healthy stem kept.

Where wilt has struck the previous year, the damaged stem reads differently from the rest. A black lesion partway up the cane marks the line, and the cut goes below it into white tissue. That stem ends up shorter than its neighbours, which is fine, since the staggered heights are part of the plan anyway.

Do not be put off by how little is left standing. The growth that produces flowers has not yet been made.

Flower count after a hard cut

Group Three plants left unpruned do not stop flowering. They flower higher each year on a thinning skeleton of old wood, and the base becomes bare.

The yearly hard cut forces multiple new shoots from low on the plant. Each shoot finishes in flowers, so the total bloom count rises while the flowering zone stays within reach.

That growth habit explains why Jackmanii can rebuild after being cut hard every spring. The plant is vigorous, and once established its roots run deep enough to support a full season’s climb.

Clearing the prunings

Cut stems with wilt damage have no compost value. Blackened material is best burned or binned, while clean, healthy clematis prunings can be shredded and left to rot down.

The first-year exception

A plant in its first year after planting is handled more severely. Cut it to 30cm even if it carries only a few stems. That sacrifices most of the first summer’s flowers, but it forces the low branching framework that every later year of cutting depends on.

If you are pruning a freshly planted Jackmanii this March, take it down to that 30cm mark and tie the stubs to the lowest rung of the support before you move on.