Growing Mushrooms Outdoors: Logs, Wine Caps and Cold Frames

The slow route: less equipment, less control, and a harvest in a completely different season from anything you can do on a shelf.

What outdoors is genuinely good for

Two things: species that want wood and time – shiitake and reishi on logs – and species that will eat a straw bed you would never waste indoors, above all wine caps. Outdoors the substrate is cheap and the season does the temperature control for you. What you give up is any schedule, and any certainty.

If you want mushrooms for a specific dinner, grow indoors. If you want a patch of garden that occasionally produces dinner, outdoors is far more than a novelty.

Log cultivation, honestly

Cut hardwood in winter with the bark on, let it rest two to four months, then drill 8 mm holes in a diamond pattern about 10 cm apart and tap in colonised dowels. Seal each hole with food-grade wax or cheese wax, and keep the log off the ground on a rack or two bricks in shade. One 50-plug set does roughly a metre of 10 cm log.

Timing is the part people underestimate: a fresh log will not fruit for a season or two while the mycelium runs through it, and then it crops for several years after. Soak the log during dry springs and stand it where it gets morning rain. Nothing you do in year one shows up in the harvest, which is precisely why the people who enjoy it are the people with patience for shelf growing.

Wine caps and straw beds

Wine caps (Stropharia rugosoannulata) are the most forgiving outdoor mushroom because they are not fussy about pasteurisation: chop clean straw, soak it, pile it 15 to 20 cm deep in a shaded bed, distribute spawn through the top two-thirds, and keep the bed damp. Mulch a path with the leftover straw so the bed does not dry in summer.

Expect the first flush in late spring, gaps through the heat of midsummer, then another in autumn, and the bed keeping productive for two or three years while the straw breaks down. The caps freeze to mush in hard frost and burst open after rain, so pick them when the margin is still curled.

A cold frame or a shaded corner

If you have a north side of a fence, a cold frame or a bed under a hedge, you already have a fruiting chamber. What you need is shade cloth in summer and a way to keep the surface from drying: a layer of loose straw over the top does both.

What to expect in year one

Outdoors, contamination is mostly a non-issue and control is mostly impossible. You will lose a bed to an unusually hot, wet month; you will find a flush three days after you forgot it existed; you will pick something and be unable to identify it.

So: grow in a place you walk past daily, keep a written note of inoculation dates, and do not eat anything from an outdoor bed you cannot positively identify – including by your own cultivated species name on the label. If there is a wild mushroom in the bed that did not come from your spawn, that is a lesson for an forager, not a prize for you.

Then enjoy the part that nobody can put in a listing: an outdoor log needs feeding twice a year and produces for a decade, while a shelf kit is a fortnight's entertainment.

The short version

1. Cut hardwood in winter, rest 2–4 months, bark on. Get the log
2. Drill 8mm holes 10cm apart in a diamond pattern. Drill
3. Tap in dowel spawn flush, seal with wax. Inoculate and seal
4. Shade, rack off the ground, soak in dry springs. Care

Kit list for this guide

MUSHROOM SPAWNShiitake Log Dowel Plug Spawn, 50 Plugs$27.00SUBSTRATEKiln-Dried Hardwood Fuel Pellets, 40 lb Bag$26.00

Written by the MycoGrow fruiting room. No claim here guarantees a harvest: a grow is a living thing in a room you control, and the room is the variable.