Reishi: the lacquered mushroom you do not eat, and why you want to grow it anyway

Of all the species we sell, reishi is the only one we tell buyers upfront: you will not be eating this. Ganoderma lingzhi, lingzhi in China and reishi in Japan, is as hard as cork and as bitter as quinine. Yet for two thousand years it has been Asia's most famous mushroom, depicted on imperial robes and temple doors, and today it can be found in north European utility rooms as a grow kit. This piece is about what it is, how it grows, and what you can honestly expect from it and what not.

What does reishi look like?

Fully grown, a kidney- or fan-shaped disc of ten to twenty centimetres, reddish brown to mahogany, with a glossy surface that looks as if it has been varnished. During growth the edge is white to yellow and later darkens to match. The underside is cream with tiny pores and bruises brown where you touch it. It grows on a stem, usually sideways, from dead or dying broadleaf wood, mainly oak and beech in Europe. A close relative, the lacquered bracket, grows wild here, looks the same and carries the same reputation.

Why does it sometimes grow like antlers?

This is the question we get with every kit. Reishi has two growth forms. With plenty of fresh air and light it forms the familiar flat disc. With lots of CO2 and little light, as in a closed bag or a cupboard, it grows as a cluster of branching, upright stalks with yellow tips: the antlers. Those antlers are not a failure but an adaptation, and Asian farms deliberately grow it that way because it is said to be worth more per kilo. If you want the disc, give air and light as soon as the first buds appear. If you want antlers, keep the bag closed longer. Both work, and both are beautiful.

How do you grow reishi indoors?

With a grow kit, slowly and warm. Unlike oyster mushrooms, reishi wants 22 to 28 degrees and high humidity, and it needs weeks rather than days. The first buds appear after two to three weeks, the disc is fully grown after six to ten. Mist, be patient, and do not move the block once growth has begun, because the disc orients to the light and grows lopsided if you turn it. For antlers keep the bag closed with a few small holes; for a disc, cut it open wide. It is the slowest grow kit we have, and the only one whose end result can sit on the mantelpiece for months.

How do you grow reishi on a log?

With plug spawn in a thick oak or beech, ideally a stump or a log buried halfway, because reishi wants the moist, warm underside. Inoculate in spring as with all species and expect the first discs only in the second or third summer. After that they return for years, every summer, in the same spot on the log. A reishi log is for the patient grower, and for anyone who wants to give a tree stump in the garden a second life that looks impressive.

What do you do with it?

Dry, slice and simmer. A mature, dried reishi can be cut into slices with a saw or a sturdy knife, and from those slices you simmer a bitter, reddish brown tea for one to two hours. That is how it has been drunk in Asia for centuries, usually with something sweet to round off the bitterness. Beyond that it is simply an object: dried, the lacquer keeps shining for years, and a fine disc on a shelf in the hallway starts conversations.

And all the health stories?

We leave those to the books and the researchers. A lot of research is done on compounds from reishi, and even more is claimed by people who profit from it. We sell a grow kit and plug spawn of a magnificent, slow, lacquered fungus that you can brew into a bitter tea and admire. Anyone expecting more should ask a doctor or pharmacist, not a nursery. Anyone expecting exactly this has, in reishi, one of the most remarkable species that can be grown in a home.