Growing mushrooms in summer: which species handle heat, and how to get the rest through it

Every June we get the same emails: the block has stopped, the log is silent, what is wrong? Usually nothing, except that it is summer. Most of the species we grow are autumn and spring species that go into standby at 25 degrees. But a few want exactly this weather, and for the rest there are ways to keep them cool. This is the nursery's summer calendar.

Which species love summer?

The tropical and heat-loving oysters. The pink oyster wants 20 to 30 degrees and is at its best in July, even on a shaded balcony. The golden oyster wants 18 to 28 degrees and does better in a summery utility room than in winter. The phoenix oyster is the summer log species: where the common oyster stalls in heat, the phoenix simply keeps flushing, which is why we sell it. And the Indian oyster on straw or coffee grounds is a summer species par excellence. See the comparison in our piece on six oyster mushrooms.

Outdoors, the wine cap is the king of summer: a wood chip bed built in April produces big mushrooms after every rain from June to October, as long as the bed stays moist. And chicken of the woods appears on a colonised log precisely in the warm months.

Which species want nothing to do with summer?

Shiitake, lion's mane, maitake, nameko, velvet shank and, to a lesser extent, the common oyster. All species that fruit at 10 to 20 degrees. A lion's mane block in a living room at 26 degrees does nothing, or makes a yellow, shapeless lump. A shiitake log waits for September. That is not failure, it is the calendar. Anyone determined to grow indoors in summer chooses a heat species or makes it cool.

How do you keep a block cool?

The coolest spot in the house in summer is usually the utility room, the cellar, the hallway or a north-facing bedroom with the curtains drawn. Put the block there, out of the sun and away from appliances that give off heat. Two tricks that genuinely work: stand the block in a shallow tray of water (a centimetre, no more) so evaporation cools it, and lay a wet tea towel over the clear box covering it. Anyone with a cool crawl space or cellar has the best growing spot in the house in July. And mist morning and evening, not midday: in the afternoon heat it evaporates instantly.

What do you do with a cold-loving block that arrives in June?

Wait, in the fridge. An unopened shiitake, lion's mane or maitake kit goes in its packaging into the bottom of the fridge and stays there quietly until the nights cool down again, as explained in the holiday piece. Four to six weeks is no problem. Better still: order those species in autumn and keep summer for the pink and the golden.

And the logs outside?

They have only one question in summer: moisture. Colonised logs do not fruit in heat, but the mycelium simply lives on as long as the wood does not dry out. Two dry weeks means watering, as in the weather piece. Logs inoculated in spring are now in their first and most vulnerable summer: keep them in the shade, cover them with leaves or chips, and leave them alone. In September a log that came through summer well rewards you with its first flush.

The bucket in summer

A bucket of straw with common oyster is a gamble in summer: colonisation is fast, but at 25 degrees and above green mould wins more often. In the warm months choose spawn of the pink, golden or Indian oyster, which grow so fast that contamination gets no chance, and put the bucket in the coolest spot outside, in the shade. Anyone wanting to start a bucket of common oyster in August is better off waiting until the nights drop below fifteen degrees.

The summer calendar in brief

• June: pink and golden oyster indoors, wine cap outdoors, keep logs moist.
• July: the same, plus chicken of the woods on old logs after rain. Cold-loving kits into the fridge.
• August: buckets with heat species, arrange wood for the stumps that come free in autumn, and order the first common oyster block for September.
• September: the season starts again: cold-loving kits, logs getting going, and the big harvest of the year.

Summer is the quiet season at the nursery, and that is exactly when we have time to answer your questions. Do send them.