Pruning Goji Berry: Hard Winter Cut, Summer Tipping and Why It Fruits on New Wood

It fruits on new growth, which changes everything

Goji flowers and fruits on shoots produced in the current season. Last year's wood does not carry the crop; it carries the buds that produce this year's shoots, which then flower along their length. This is the opposite of a blackberry or a blackcurrant, and it means hard pruning does not cost you a crop the way it would on those plants. Cut a goji back hard in winter and it responds with vigorous new shoots that flower the same summer.

An unpruned goji goes the other way. It keeps extending the same long stems year after year, and each year the flowering zone moves further out towards the tips, which by then are lying on the ground somewhere beyond the plant. You end up with a large tangled mound bearing a modest crop entirely out of reach on its outside. Restoring one is simply a matter of cutting it back hard once and starting again; the plant does not resent it.

The winter cut, step by step

Prune in the dormant season, once the leaves are off and the worst of the cold has passed. Late winter, before buds swell, is the ideal moment. The plant is bare and you can see the structure, and the cut surfaces are not sitting through months of freezing weather. Use sharp pruners and loppers; goji wood is fibrous and crushing it with blunt blades leaves a ragged wound.

The aim is a plant with a clear leg of bare stem at the bottom and four to six upright framework stems above it, all tied to a support, each carrying short spurs that will throw the fruiting shoots. Nothing should be able to reach the ground. That structure is what makes the plant pickable, keeps the fruit off the soil, and stops the stem-tip rooting that turns a goji into a thicket.

1. Clear everything below about 15 inches (38 cm) Cut out every shoot arising from the lower part of the plant, right to the base. A clear leg keeps fruit and foliage off the soil, lets you hoe and see suckers, and removes the stems most likely to arch down and root. This is the cut people skip and it is the most valuable one.
2. Select four to six framework stems Keep the strongest, best-placed upright stems and cut every other thick stem out at the base. Fewer, well-lit stems fruit far better than a dense mass, because goji flowers along shoots that get direct sun and produces almost nothing in shaded interior growth.
3. Shorten the framework and cut side shoots to spurs Head the retained stems back to 5 to 6 feet (1.5 to 1.8 m), or to whatever height you can comfortably reach, cutting to an outward-facing bud. Then cut every side shoot that fruited last summer back to two to four buds from the framework stem. Those stubs produce this year's fruiting shoots.
4. Tie the framework in firmly Tie each retained stem to its cane or wire with soft string in a figure of eight, before growth starts. A framework tied while bare stays where you put it all season. A plant left untied is carrying fruit on the ground by midsummer, and fruit touching soil rots and feeds slugs.
5. Clear the debris and check the barrier Rake out all the prunings from under the plant and take them away. Goji prunings left lying on damp ground can root. While the plant is bare, check that the root barrier is intact and that no root has crept over the lip.

Summer tipping keeps it in bounds

Winter pruning sets the structure; summer work stops the plant undoing it. Once new shoots reach about 24 inches (60 cm) and start to arch, pinch or cut the tips out. Tipping forces side shoots, which flower, so it usually increases the crop rather than reducing it, and it stops the shoot growing on until it flops to the ground and roots.

Do this two or three times through the growing season, whenever a wave of shoots gets long enough. It is not precise work: run a hand along the outside of the plant, and anything longer than your forearm heading downwards gets shortened. Stop tipping by the end of summer so the last growth has time to harden before frost.

Also remove suckers on every pass. Pull rather than cut, so the base of the sucker comes away with it. On a plant behind a barrier this is a handful of shoots a year. On an unbarriered plant in a border it becomes a permanent chore, which is the real reason to plant in a container or behind a barrier in the first place.

Do not shorten the framework in summer expecting a tidier plant. Heading back thick stems in leaf makes the plant respond with a burst of soft shoots from every bud below the cut, and those shoots will not have hardened before winter. Summer work is tipping thin new shoots only.

Renovating a plant that has been left alone

A goji that has gone unpruned for several years is a sprawling mound with a bare, congested middle, dozens of stems, several rooted tips out at the edges, and a scatter of suckers. It looks like a lost cause and it is not. Because the plant fruits on new wood, you can cut the whole thing down to 12 to 18 inches (30 to 45 cm) in late winter and it will regrow strongly, giving you a light crop the same year and a proper structure to work with the next.

Do the ground work at the same time, while everything is visible and cut low: trace and sever every rooted tip, dig the rooted points out entirely, pull every sucker, and put in the support and the barrier you should have had at the start. Then select four to six of the new stems in early summer, tie them in, and pinch the rest out. The plant is back to a manageable structure in one season.

Record what you cut and how the plant responded. Goji is vigorous enough that hard pruning is low-risk, but the useful figure is how many strong shoots came from a given number of retained stems on your soil, and that tells you whether to keep four or six next winter.