Growing mushrooms on outdoor logs means drilling holes in a freshly cut hardwood log, tapping in inoculated wooden spawn plugs, sealing every hole and both log ends with beeswax, then standing the log in shade. Colonisation takes 12 to 18 months. After that the log crops for three to five years with almost no input from you.

It is a sustainable way to turn a waste resource into food. If a tree has fallen or branches have been pruned, this is the perfect use for them. It is slower than our indoor mushroom growing kits, but once the log is set up you leave it to its own devices and the mushrooms come in their own time.

Kits start at £10.00 and drop to £8.00 each when you order more than 2 of the same variety, which is why most people do two or three logs at once. Choose yours on the outdoor mushroom log growing kits page before you cut anything, because wood and timing both follow from it.

What do you need to inoculate a log?

In the kit: thirty inoculated spawn plugs, beeswax for all thirty holes and both cut ends, and printed instructions. Keep them refrigerated until the day you use them. They hold for two to three months, which is why a log kit works as a gift: open it in December, inoculate in March.

What you supply: a drill with a charged battery. An 8mm bit, the only size that fits the plugs. A rubber or wooden mallet, or a hammer used gently. A way to melt wax, such as an old tin standing in a pan of simmering water. A brush, gloves, and the log. Do not use a good kitchen pan, because beeswax never fully comes out.

Which log, and when should it be cut?

Freshly cut hardwood, every time. Oak, beech, birch, alder, ash and elm all work here, and fruit woods such as apple and pear are fine. Softwoods and conifers are out, because their resins fight the fungus you are trying to establish. Your log should be about 15 to 20cm in diameter and around a metre long. Thinner logs dry out and run short of food; much thicker and one kit cannot colonise the volume fast enough. Keep the bark intact, because bark holds moisture in.

A guide to choosing the right wood for your mushroom log.

For sourcing and species detail, read which logs are best for growing mushrooms in the UK, and for the felling and inoculation windows month by month, the UK mushroom log growing calendar.

How do you drill the pattern correctly?

The pattern exists to get mycelium from thirty starting points to meet and join across the whole log before anything else claims it. Spread the plugs evenly and they close ranks. Cluster them and you leave open territory.

Work in rows running the length of the log, parallel to the grain. With 30 plugs that means five rows of six, or six rows of five. Space the holes along each row about a hand's width apart, and space the rows evenly around the circumference so you go right round the log, not just one face.

Offset each row against its neighbour by half a spacing. That is the whole trick. Straight rows leave unclaimed strips between them, whereas offsetting turns the layout into a diamond grid where every hole sits the same distance from its neighbours.

Drill slightly deeper than the plug is long, so it sits just below the surface with a small pocket beneath. Use the drill's depth stop, or wrap masking tape round the bit as a marker. Work from one end and finish each row before starting the next.

Hammering and sealing: the part people rush

Tap each plug in until it sits flush with the bark or a whisker below. Flush, not proud. A plug standing out gets knocked off when the log is moved, and one hammered until it splits has lost most of its spawn.

Then seal. Melt the beeswax and dab a covering over every plug. The wax stops the hole drying, keeps rain from washing spawn out, and blocks insects and stray spores.

Now the part half of all first time growers skip: seal both cut ends. End grain is thousands of open straws pointing outward, the fastest route for moisture to leave the log. Bark seals the sides. Nothing seals the ends but you. A log with bare ends can dry through the middle over one hot summer, and colonisation stops.

Where should the log live?

Shade and damp air. Under a hedge, on the north side of a shed, or against a fence with no afternoon sun. Full sun will cook it.

Raise the log off bare soil on bricks, a slab or a pallet offcut. Ground contact invites soil fungi and slugs to compete for wood you have paid for.

Stacking works well. Three or four logs stacked log cabin style, each layer crossing the one below, hold humidity between them and shade one another. Leave airflow: a sealed pile of wet wood under plastic grows mould, not mushrooms.

Water only in dry spells. A UK winter needs nothing. In a dry summer fortnight, hose each log once a week until water runs off it for a minute or two. A quick splash does nothing.

Freshly inoculated logs stacked in a shaded position, ready to colonise.

What happens during the 12 to 18 month wait?

Very little that is visible, which is why the wait unsettles people. The end grain tells you most. Over the first six to nine months, white or cream flecking should creep in from the edges of the cut face. That is the mycelium claiming the wood.

The bark loosens slightly on a well colonised log, and the log sounds duller when knocked. Darkening and a little algae are normal. Bright orange, black or fuzzy blue patches are not, and usually mean a competitor got in through an unsealed end.

First fruiting usually arrives inside that window, often after the first proper autumn rain. From then it crops for three to five years.

Left: a freshly inoculated log. Right: a fully colonised log producing its first flush of mushrooms.

How do you trigger and harvest a flush?

Most of the time you do nothing. A temperature drop plus heavy rain does it, which is why UK logs tend to fruit in autumn and again in spring.

To nudge one along, soak it. Submerge the log in a water butt, wheelbarrow or cold bath for a day, then stand it back in the shade. Do that once or twice a season at most, and only on a log that has already fruited.

Harvest by twisting the cluster away at the base or cutting it flush, before the caps flatten and turn up at the edges. Shiitake is best taken while the cap edge is still curled under. Oysters go from ideal to floppy in a day in warm weather, so check daily once you see pins.

Does the method change by variety?

The method stays the same. The emphasis shifts. Every variety in our outdoor range has been chosen because it suits the UK climate, and each has a wood and a rhythm it gets on with best.

Some of the mushroom species best suited to outdoor log growing in the UK.

Shiitake (Lentinula edodes) is the classic log species, the most widely cultivated mushroom on logs worldwide. Oak and beech suit it, and it rewards a full soak to trigger flushes. Our full guide to the Shiitake log growing kit covers it in depth.

White Oyster (Pleurotus ostreatus var. florida) colonises fastest and forgives most, so start there. The outdoor case for it is covered in can you grow White Oyster mushrooms outdoors in the UK.

Summer Oyster and Tarragon Oyster are UK natives, untroubled by our weather, and Tarragon Oyster carries a distinct aniseed note.

Lion's Mane (Hericium erinaceus) prefers a denser wood such as beech and deeper shade. Golden Enoki (Flammulina velutipes) fruits in the cooler months and extends the season as other varieties wind down.

Turkey Tail (Trametes versicolor) is the newest variety and a UK native, found on dead and dying hardwood. Fan shaped, with concentric colour bands, and tough and leathery rather than tender, so it is traditionally prepared as a tea or decoction rather than cooked as a vegetable, with a long history of traditional use particularly in East Asia. Being a native decomposer, it takes to logs readily. See our full guide to the Turkey Tail log growing kit.

Worked example one: one afternoon, one log

A Saturday in early April. One birch log felled three weeks earlier, 18cm across and just over a metre long, and one Shiitake log kit out of the fridge.

1.15pm. Log across two trestles at waist height, chocked so it cannot roll. Wax on to heat in an old tin inside a pan of simmering water, where it sits while you drill.

1.30pm. Mark out. Chalk five lines along the log, evenly spaced around it. On the first, mark six points a hand's width apart, starting a few inches in from the end. On the next line, shift the marks half a space so they fall between their neighbours. Thirty marks, counted twice.

1.50pm. Drill. 8mm bit, tape depth marker, straight in perpendicular to the surface. Row by row, rolling the log in the chocks, blowing dust from each hole. Twenty minutes.

2.15pm. Plugs out of the fridge, tapped in flush. Firm taps, not swings. Fifteen minutes.

2.35pm. Wax. Dab over each plug row by row, then both cut ends, edge to edge, until no bare grain shows. The ends take longer than the holes.

3.00pm. Carry the log to the north side of the shed, set it on two bricks clear of soil, hose it thoroughly, and wire on a label with the variety and date. Under two hours of work, and nothing more until summer.

Worked example two: three logs across two years

Year one, April. Three alder logs done in one afternoon: White Oyster, Shiitake, Turkey Tail. Stacked log cabin style on a pallet behind the greenhouse.

Year one, July. Three weeks without rain, so each log gets a thorough hose once a week. Ten minutes, nothing more.

Year one, October. End grain checked. White flecking across most of the White Oyster cut face, patchier on the Shiitake, fine white lines on the Turkey Tail.

Year two, April. Bark on the White Oyster log has loosened and it sounds dull when knocked. Twelve months in.

Year two, September. Heavy rain after a dry August. Pins appear along the White Oyster log within a week, and the first flush comes off six days later.

Year two, November. The Shiitake fruits after the first cold snap, at seventeen months. The Turkey Tail has put out small overlapping brackets along one flank since late summer. Three logs, one afternoon of work, and a crop that returns for three to five years. If that suits the corner behind your shed, the log inoculation range is where to start.

What kills a log?

The same five mistakes. Softwood or conifer, which will not colonise. Unsealed ends, the commonest failure of all. Full sun, which pulls moisture out faster than it can be replaced. Old wood, already occupied by something thirty plugs will not evict. And impatience: logs get dumped at month eight because nothing has happened, when nothing happening at month eight is exactly what should happen.

What if the log never fruits?

Give it longer first. Eighteen months is the far end of the range, not a deadline, and a thick log in deep shade can run past it. Then check three things. Is the end grain flecked white? If so the fungus is alive and you are only missing a trigger, so soak the log for a day and put it back. Is the wood bone dry under the bark? Soak it and move it somewhere damper. Is something else fruiting on it? That log has been taken over, so move it away from the others and start again.

Log kits or indoor kits?

Want mushrooms this month? Buy an indoor kit. Want them every year for five years? Inoculate a log.

Indoor ready growing kits arrive already colonised. You cut the holes and mist twice daily, and oyster varieties typically crop in 7 to 10 days, with 2 to 3 harvests over 3 to 4 weeks. The White Oyster ready growing kit at £19.48 and the Shiitake ready growing kit at £18.95 are where most people begin.

Frequently asked questions

An afternoon with a drill now buys a crop every year well into the next decade. Pick your variety, find your log, get the wax on. Merryhill Mushrooms has grown mushrooms in West Sussex for six generations, and the log method is the closest thing to how they grow in the wild.