How to Prune a Leggy Fatsia Japonica and Make It Shoot From Bare Stems

Why fatsia goes leggy, and why that is fixable

Fatsia holds each leaf for two or three years and then drops it, and it does not replace leaves further down a stem once they have gone. Over five or six years the result is predictable: a clean, thick, unbranched stem with nothing on it, carrying a rosette of enormous leaves at the very top. In deep shade the stems also stretch toward whatever light there is, so the leggy plant is usually leaning as well as bare.

This looks terminal and is not. Unlike many broadleaved evergreens, fatsia carries dormant buds all the way down its bare wood, and it breaks readily from them when the top is removed. A stem cut back to eighteen inches (45 cm) of bare wood in spring will typically push three to five new shoots within six to eight weeks, and those shoots branch, which is how a single-stemmed plant becomes a full multi-stemmed one.

This is the single most useful thing to know about the plant, and the reason so many good fatsias in old gardens are plants that were cut down at some point. Nothing else you can do produces as large an improvement for as little work.

The hard cut, in spring only

Timing is not negotiable. Cut in spring, as growth is starting but before the new leaves expand, when the plant has the whole warm season ahead of it to rebuild. A hard cut in autumn leaves fresh wounds and no foliage going into cold weather, and the stumps often die back to the ground or rot. A hard cut in midsummer removes the plant's entire leaf area at the hottest point of the year and stresses the roots badly.

Use clean sharp loppers or a pruning saw. Fatsia stems are surprisingly soft and pithy for their thickness, and blunt pruners crush rather than cut, leaving a bruised end that dies back an inch or two. Cut just above a visible dormant bud or leaf scar where you can see one; if you cannot, cut anywhere on sound wood, since buds are distributed along the whole stem.

1. Decide the finished height first Pick the height you want the new foliage to start from and cut roughly six inches (15 cm) below it, because the new shoots emerge below the cut and then grow up past it. For most plants a cut at knee to waist height, twelve to thirty inches (30 to 75 cm), works well.
2. Stagger the stems on a multi-stemmed plant If the plant has three or more stems, cut them at different heights spread over about a foot (30 cm). Cutting them all level produces a flat-topped shape that takes years to lose. Staggered cuts give a natural layered outline from the first season.
3. Take the whole top off in one clean cut Do not shorten in stages down the stem. One cut through sound wood at the chosen height, angled very slightly so water runs off, is all that is needed. Leave no snags or torn bark.
4. Remove any dead or damaged stem entirely A stem that is soft, hollow or discolored inside when cut is dead. Take it right out at ground level rather than leaving a stump, which will only rot back into the crown.
5. Mulch, and water through the regrowth Lay two inches (5 cm) of compost over the root area and keep the soil evenly damp while the new shoots push. A cut plant has no leaves to lose water through, so do not drown it; damp, not wet, until the shoots open.
6. Thin the new shoots if there are too many If a stump produces six or seven shoots, rub or cut out the weakest once they are a few inches long, leaving three or four evenly spaced. Crowded shoots at one point make a congested head later.

The gentler alternative: renewal over three years

If a hard cut on the whole plant feels too drastic, or you cannot accept a bare period of six to eight weeks in a prominent position, do it stem by stem. On a multi-stemmed clump, cut one third of the stems back hard in the first spring, another third the next spring, and the last third the year after. The plant keeps leaves throughout and never looks cut down, but ends up entirely rebuilt.

This method also suits container plants and indoor plants in visible positions. The trade-off is time: three years rather than one season, and the untouched old stems continue to stretch while you wait.

There is one situation where the hard cut is the only option, and that is a plant that has been badly scorched by sun and moved into shade. The pale hard leaves will never green up, and waiting for them to fall naturally takes two years. Cutting back removes them all at once, and the shoots that follow grow up already adapted to the new position.

Routine cuts, and what not to do

Outside the hard-cut job, fatsia needs almost no pruning. Remove yellowing old leaves at the base of the stalk, take out any stem that is dead or leaning badly into a path, and cut off frost-blackened shoot tips once you can see where live wood starts in spring. That is the whole routine.

Never shear a fatsia. The leaves are far too large for shears, and a cut through the middle of a leaf leaves a permanent brown-edged half-leaf that stays on the plant for two more years. Every cut on this plant should be at a stem or at a leaf stalk, never across a leaf blade.

Do not prune in autumn just because that is when the tidying urge arrives. The flowers open in late autumn, so autumn pruning removes the one seasonal display the plant offers, and the cut stems face winter without leaves. Note the spring date of each hard cut and how many shoots each stump produced; after two plants you will know exactly what height to cut at to get the shape you want.