How to Grow Fingerroot (Boesenbergia rotunda): Rhizomes, Shade and Harvest

Fingerroot, Boesenbergia rotunda, is the ginger relative that grows a cluster of slim, finger-like rhizomes all joined at the top, like a hand — which is where both its English name and its other common name, Chinese keys, come from. The skin is brown, the flesh inside is yellow, and the flavour is recognisably in the ginger family, so anywhere you would reach for gingerroot you can reach for this instead. It is also a genuinely pretty plant with fragrant flowers, which makes it one of the few edibles worth putting in a shady border on looks alone.

Fingerroot is a shade plant, and that changes everything

Most kitchen crops are sun crops. Fingerroot is not. It grows best in half shade to full shade, which is exactly what you would expect of a forest-floor ginger: it evolved under a canopy, and strong direct sun scorches its broad, soft leaves rather than feeding them.

That single fact solves a problem most gardens have. The shaded strip beside a fence, the bed under a tree, the corner where tomatoes sulk — those are fingerroot’s best positions. Pair the shade with rich, moist soil, plenty of organic matter and a mulch and you have reproduced a forest floor fairly accurately.

The geophyte cycle: why the plant disappears, and why that is useful

Fingerroot is a geophyte. The permanent part of the plant is the rhizome underground; the stems above ground are annual, produced fresh each season and dying back afterwards. The plant may behave as evergreen in a warm, frost-free climate and deciduous where there is a cool season, but the underground engine is the same either way.

This is what lets gardeners well outside the tropics grow it. Because everything that matters is a storage organ, you can lift the rhizome in autumn, keep it through the winter, and replant in spring — the plant does not know or care that it spent the cold months in a box rather than in the soil. In practice:

Zones 5 to 10a — grow it as an annual: plant in spring, lift the rhizome before winter, replant the following spring. In zone 10a it can also be kept as a perennial in the ground with the right winter care, planted in spring.
Zone 10b — plant in spring to summer. Winter lows here stay around 2 °C (35 °F) and above, which the rhizome will take.
Zone 11a — plant spring to autumn.
Zone 11b and warmer — plant at any time of year.

The non-negotiable is frost. A frozen rhizome is a dead rhizome, and no amount of mulch will save one in a hard freeze. Mulch does earn its place in a mild winter, and over young rhizomes at any time, by buffering the soil temperature and holding moisture.

Soil, water and feeding

Fingerroot wants soil that is rich and consistently moist, with an average to large amount of water. It grows fastest in humid, hot conditions, and in a dry climate the limiting factor is usually humidity and soil moisture rather than heat.

Work in organic matter and humus before planting and top up each season. A rhizome crop is being asked to bulk up a storage organ in a single growing season, and it can only do that if the soil it sits in is fertile and never dries hard. A surface mulch is the cheapest way to keep moisture even — and even moisture, not constant flooding, is the goal.

Growing fingerroot in a container

Fingerroot takes to pots well, which suits anyone who has to bring it under cover in winter. Get the container right and the rest is easy.

Size the pot generously. Use at least 10 litres (2.6 gallons), or a pot at least 200% larger than the rhizome you are planting, whichever is bigger. The crop is the underground growth, so a cramped pot directly caps your harvest.
Mix for air as well as water. A standard potting mix, or peat-based soil with perlite added, gives the drainage and aeration the rhizome needs. Waterlogged, airless compost is what rots rhizomes.
Enrich it. Add organic matter and humus to the mix.
Mulch the surface with a fine mulch to slow evaporation — pots dry out far faster than open ground.
Refresh the soil. Change it every few years at minimum, but yearly is better. If you would rather not repot completely, at least mix in fresh perlite or a similar material to restore air movement in a mix that has slumped and compacted.

Repotting time is the natural moment to divide, so the yearly refresh and propagation are really one job.

Propagation: divide the rhizome

Fingerroot can be raised from seed, but seed is difficult and there is no reason to bother. Division is fast, reliable and gives you an exact copy of the parent.

Divide from autumn into winter, once the top growth has finished for the season. At that point the plant has moved its resources into the rhizome and is not carrying leaves that will wilt while it re-roots.

If you look at the clump and cannot see an obvious place to cut — no clear natural division between the fingers — do not force it. Wait until the end of winter, just before growth restarts. By then the buds are swelling and it is far easier to see which portion belongs with which growing point, so every piece you cut has a shoot to grow from. A division without a bud is just a piece of stored starch that will rot.

Whichever timing you use, keep each piece a decent size. A larger division has more stored energy and produces a bigger plant, and a bigger plant produces a bigger harvest.

Growing fingerroot indoors

Indoors is possible, with one condition: give it as much light as you can. That sounds contradictory for a shade plant, but it is not. Full shade outdoors is still far brighter than a typical room, so the plant that wants shade in the garden still needs your brightest window inside. A bright spot out of harsh direct midday sun is ideal.

Everything else applies as for a container outdoors: a large pot, an open mix, steady moisture and reasonable humidity — dry indoor air in winter is the usual cause of crisping leaf edges.

Pests and diseases

Rhizome flies — the ones that matter, because their larvae tunnel into the rhizome itself, which is both the crop and the plant’s survival organ. Damaged rhizomes rot in storage, so inspect anything you lift for winter and discard tunnelled pieces rather than storing them with sound ones.
Phyllosticta zingiberi — a leaf-spot fungus of gingers. It is encouraged by wet foliage and stagnant air, so water at soil level rather than over the leaves, and do not crowd plants.

Pruning amounts to removing infected leaves, in autumn to winter or as soon as you spot them. Taking off spotted foliage early removes the spore source before it spreads through the clump.

Flowering

Fingerroot blooms in summer, and the flowers are fragrant — a real ornamental feature, and good enough to cut. They are pink and white with darker spotting, carried in a dense head low on the plant. Bees and butterflies do the pollinating, so a patch of fingerroot earns its place in a pollinator planting as well as in the kitchen garden.

Harvest and uses

The plant reaches 1-2 m (40-80 inches) and grows at a medium to fast rate, so a spring planting gives you a full-sized clump within the season.

The rhizome

Lift the rhizome in summer, or in autumn if you are lifting for winter storage in a cold zone. Peel off the brown skin to reach the yellow flesh. Use it as you would ginger: raw, as a spice, in beverages, in stir-fries, or cooked in longer dishes.

The leaves

The leaves are edible too, harvested in spring and summer. The most efficient approach is to take the leaves at the same time you lift the rhizome — you are removing the top growth anyway, so nothing is wasted and you are not weakening a plant that still needs its foliage to bulk up underground. Use them in salads, stir-fries or cooked dishes.

Common mistakes

Planting it in full sun because it is a vegetable. It wants shade.
Letting the soil dry out. A stressed plant makes small rhizomes, and you will not see the damage until harvest.
Using a small pot. The pot volume sets the crop size.
Leaving rhizomes in the ground through frost in a cold zone instead of lifting them in autumn.
Cutting divisions with no visible bud. Wait for late winter if the clump does not divide cleanly.

For the full plant profile see our Fingerroot plant growing page.