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    How to grow chestnut mushrooms

    Pholiota adiposa

    Chestnut mushroom fruits on amended hardwood sawdust at 55–75°F (13–24°C), with a first harvest about 6–11 weeks after spawning. Slow colonization and a need for high humidity make it a step up from oysters.

    By Derick · October 24, 2026

    Fruiting temperature
    55–75°F (13–24°C)
    Humidity
    85–90% RH; over 95% in one trial
    Spawn to first harvest
    About 6–11 weeks
    Grows on
    Amended hardwood sawdust, or logs

    Difficulty: Moderate. GroCycle calls chestnut relatively easy, though not as easy as oysters, and its blocks take 4–6 weeks to colonize (GroCycle).

    Chestnut growing conditions at a glance

    StageTemperatureHumidityFresh air / CO2LightDays
    Bulk colonization73–77°F (23–25°C) in one trialSealed bagFiltered bagDark4–6 weeks
    Pinning55–75°F (13–24°C); one trial chilled bags at 32–41°F (0–5°C) for 3–5 days first85–90%; pins won't form if it's drySlit cut in the bagIndirect, bright enough to read by12–28 days
    Fruiting55–75°F (13–24°C); best yields at 57–61°F (14–16°C) in one trial85–90%; over 95% gave the best yields in one trialNot statedIndirect; 12 hours a day in one trial5–10 days after pins
    Where these numbers come from
    • Colonization: GroCycle gives chestnut four to six weeks to colonize a block (GroCycle), after 2–3 weeks for the grain spawn (GroCycle). A 2016 trial at the Beijing Academy of Agriculture and Forestry Sciences ran filter-capped bags at 73–77°F (23–25°C) in the dark (Mycosphere).
    • Pinning and fruiting: GroCycle fruits chestnut at 55–75°F (13–24°C) and 85–90% humidity in indirect light. Pins take 12–28 days, and the first harvest comes 5–10 days after that (GroCycle). The Beijing trial chilled bags for 3–5 days at 32–41°F (0–5°C) after the spawn run, then fruited them at 61–68°F (16–20°C) and 80–90% RH under 12 hours of light a day (Mycosphere).
    • Best yields: A Kagoshima University trial on Japanese cedar (sugi) sawdust got its best yields and mushroom shape at 57–61°F (14–16°C) and over 95% RH (Kagoshima University).
    • The timeline rests on GroCycle, a company that sells growing kits and courses. Our grow timeline guide uses the same figures.

    What does chestnut grow on?

    • Amended hardwood sawdust

      The best choice, per GroCycle (GroCycle). In a Korean trial, poplar sawdust gave the most mushrooms of three woods, and mixing in sawtooth oak lowered yields (Korea National University of Education).

    • Cottonseed hull mix

      The Beijing trial used 60% cottonseed hulls, 18% sawdust, 15% wheat bran, 5% corn flour and 1% each gypsum and lime, at 65% water (Mycosphere).

    • Hardwood logs

      Chestnut grows on many hardwood logs but best on maple or oak. Expect about a year to the first flush, then several years of mushrooms (GroCycle).

    • Straw or cardboard

      Worth a try, but GroCycle expects a smaller harvest, at least from cardboard, which feeds the mycelium less than hardwood (GroCycle).

    How to grow chestnut, step by step

    1. Make or buy grain spawn

      Grain spawn takes 2–3 weeks and is ready when the grain is covered and uniformly white (GroCycle).

    2. Spawn into sawdust and wait

      Mix the spawn into sterilized amended sawdust in a filter bag and leave it 4–6 weeks (GroCycle). Colonization is done when white mycelium covers the whole block (timeline guide).

    3. Cut a slit and keep it humid

      Cut a slit in the bag and move the block into 55–75°F (13–24°C), 85–90% humidity and indirect light. Spray the opening two to three times a day; in a dry climate, cover it with a loose plastic bag with plenty of holes (GroCycle). Done when pins show, after 12–28 days.

    4. Grow out and pick

      Keep spraying for 5–10 days. Pick while the caps are young, before they flatten, by twisting off the whole cluster (GroCycle).

    5. Rest for another flush

      Expect one or two more flushes, each smaller than the first (GroCycle). Our second-flush guide covers rest and soaking. Done when the block stops pinning.

    What's different about growing chestnut?

    It wants more humidity than most

    Chestnut needs steady moisture to pin: without it, pins won't form, and pins that dry out stop growing (GroCycle). A Kagoshima University trial found its best yields at over 95% RH and 57–61°F (14–16°C), and judged that chestnut needs somewhat higher humidity than other edible mushrooms (Kagoshima University).

    Not the supermarket chestnut

    Growers sometimes sell brown button mushrooms (cremini, Agaricus bisporus) as "chestnut mushrooms". Pholiota adiposa grows in clusters on wood, with scaly orange-brown caps and long, crisp stems. On logs, check look-alikes: shaggy scalycap (Pholiota squarrosa) is usually paler, with much larger caps and stem scales, and the deadly funeral bell (Galerina autumnalis) has no scales on its cap (GroCycle).

    Strain makes a big difference

    In the Beijing trial, five strains on the same substrate ranged from about 41% to 68% biological efficiency over two flushes. The control strain took 8–9 days longer to colonize and 11–12 days longer to pin than the top strain (Mycosphere).

    When and how do you harvest chestnut?

    Chestnut is ready while the caps are young, before they flatten out. Twist and pull off the whole cluster without taking too much substrate (GroCycle); North Spore twists clusters off its kits the same way (North Spore help center).

    Expect one or two more flushes, each smaller than the first. GroCycle gives no interval between them (GroCycle). For yield, strains in the Beijing trial gave about 41–68% biological efficiency over two flushes (Mycosphere).

    Common chestnut problems

    No pins after two weeks

    That's normal for chestnut: pins can take 12–28 days (GroCycle). Check humidity first, then work through our pinning guide.

    Pins dry out and stop

    Pins that dry out stop growing (GroCycle). Spray more often or add a humidity tent; see stalled pins.

    Green patches during colonization

    Green patches are often trichoderma. Use the contamination ID table before you toss the block.

    Mushrooms growing inside the bag

    For chestnut, North Spore says you can ignore them, or break off and compost any you can reach (North Spore help center).

    Amber droplets on the block

    That's mycelial exudate, a natural, harmless byproduct of the mycelium digesting its food (North Spore help center).

    Tracking a chestnut grow in Hypha

    Hypha tracks each chestnut block from inoculation through harvest. It sets reminders from typical timings, and you can adjust them for each block to fit chestnut's 4–6-week colonization. Because strains differ so much, link each block to its parent culture and compare each strain's success and contamination rates. Download Hypha to start.

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    Chestnut growing FAQ

    How long does chestnut take to grow?

    Chestnut takes about 6–11 weeks from spawning to first harvest, or 8–14 weeks counting the grain spawn (timeline guide). A ready-to-fruit kit pins in 12–28 days and is picked 5–10 days later; logs take about a year (GroCycle).

    Can you grow chestnut mushrooms indoors?

    Chestnut grows well indoors on a countertop or shelf, from a kit or your own sawdust blocks. Give it indirect light, bright enough to read a book by (GroCycle).

    What temperature do chestnut mushrooms need?

    Chestnut fruits at 55–75°F (13–24°C), so a normal or slightly cool room works (GroCycle). One trial got its best yields at 57–61°F (14–16°C) (Kagoshima University).

    Is chestnut hard to grow?

    Chestnut is relatively easy, but harder than oysters (GroCycle). The hard parts are waiting out a 4–6-week colonization and keeping humidity high enough for pins.

    Are chestnut mushrooms the same as cremini?

    No. Cremini (Agaricus bisporus) are sometimes sold as chestnut mushrooms, but Pholiota adiposa has much longer, crisp stems and grows on wood, not compost (GroCycle).

    Sources

    1. GroCycle (grocycle.com/chestnut-mushrooms)
    2. GroCycle (grocycle.com/how-to-make-grain-spawn)
    3. Mycosphere (mycosphere.org/pdf/Mycosphere_7_2_11.pdf)
    4. Kagoshima University (ir.kagoshima-u.ac.jp/records/7509)
    5. Korea National University of Education (koreascience.or.kr/article/JAKO200218164192320.page)
    6. North Spore help center (north-spore.reamaze.io/kb/troubleshooting-your-spray-and-grow-kit/how…)
    7. North Spore help center (north-spore.reamaze.io/kb/troubleshooting-your-spray-and-grow-kit/whe…)
    8. North Spore help center (north-spore.reamaze.io/kb/troubleshooting-your-spray-and-grow-kit/wha…)

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