Growing Mushrooms in Winter: Is It Possible?

Growing Mushrooms in Winter: Is It Possible?

Yes, growing mushrooms in winter is absolutely possible, and for a lot of species it is one of the best times of year to do it. Indoors you can grow all winter long in almost any climate, and several cold loving species like oyster, shiitake, and enoki actually fruit better when the air turns cool.

The part most beginners get wrong is what they blame when a winter grow stalls. They assume the cold killed it. Nine times out of ten it was the dry, heated indoor air that crashed the humidity and dried the surface faster than pins could form. Get the humidity right and keep the two growth stages at their own temperatures, and winter stops being an obstacle and starts being an advantage.

Best Mushrooms to Grow in Winter Indoors

Two winters ago the propane heater in the back corner of my warehouse quit for four days in the middle of January before I noticed the thermostat had failed. The oyster and shiitake blocks on that side of the room did not skip a beat. The lion's mane tray six feet away stalled cold and never fully recovered that flush. That one broken heater taught me more about which species actually belong in a winter lineup than any chart could.

The easiest way to succeed in winter is to grow species that already like it cool, so the season works with you instead of against you. Oyster, shiitake, and enoki all handle cold far better than warm loving mushrooms, and enoki is literally called the winter mushroom because it fruits at temperatures that would stall almost anything else. Lion's mane and button types can be grown in winter too, but they want a warmer room and are better treated as heated space crops.

Here is roughly how cold each common species will still fruit. The colder a mushroom will tolerate, the more forgiving it is when your grow space dips at night in winter.

Those numbers are approximate and strain dependent, but the ranking holds. If your winter grow space is cold or swings a lot, start with oyster or enoki. If you can keep a room warm, lion's mane and button mushrooms open up too. Here is how the main winter candidates compare across the things that actually matter for a beginner.

Winter Colonization vs Fruiting Temperature: What Changes

My first winter running grows out of a single room, before Out-Grow had anything like a proper facility, I kept one shelf near the furnace vent and another by a drafty window three feet away. I did not plan it that way. It just happened to be the only two spots in the house that were not fighting over the same thermostat. The shelf by the furnace colonized bags in under two weeks. The spot by the window is where I started fruiting them, almost by accident, and it worked better than anything I had done on purpose up to that point.

The single biggest winter mistake is treating the whole grow as one temperature. Colonization and fruiting want different things, and in winter that split is easier to hit than in summer because you can use a warm spot for one and a cool spot for the other. Colonization, when the mycelium is running through the grain and substrate, likes it warm, roughly 70 to 80°F (21 to 27°C). Fruiting, when the mushrooms actually form, prefers cooler air, roughly 55 to 68°F (13 to 20°C) for most gourmet species.

Winter is handy here. The warmest clean corner of a heated home is usually right for colonization, and a cooler room, an enclosed porch, or a spot near a window often lands in the fruiting range on its own. For cold specialists you can push the fruiting temperature much lower. Here is how the target ranges stack up on a thermometer.

Notice that the cold does not just permit fruiting, it can improve it. Dropping enoki from its pinning range into the 37 to 41°F (3 to 5°C) window during cap development produces firmer, tighter stems, which is exactly the kind of trick winter hands you for free. The full stage by stage picture, including humidity and fresh air exchange, looks like this.

How to Keep Humidity for Mushrooms in Dry Winter Air

The first January after we moved Out-Grow into the current warehouse, I walked in one morning and found three blocks stacked near the heat register with cracked, crusted caps and pins that had shriveled overnight. Nothing else in the room had changed except that the furnace had kicked on hard the night before. I moved those same blocks eight feet away from the register the next day and misted the space around them, and the next flush came in fine.

Holding humidity is the whole ballgame in winter, because home heating is a dehumidifier in disguise. Warm the air of a house in January and the relative humidity often drops well below 30 percent, while your fruiting mushrooms want 85 to 95 percent. That gap is the number one reason winter grows fail, and it is completely fixable. When I sort winter grow problems by what actually caused them, dry heated air is by far the biggest slice.

The reliable fix is to stop trying to humidify a whole dry room and instead enclose a small fruiting space you can actually control. A grow tent, a clear tub, or a bag with a humidity dome traps the moisture the block gives off and lets a small humidifier do the rest. Mist the walls and surfaces of that space to hold humidity, not the developing pins directly, and let evaporation carry it. Grouping several bags together also helps, since they raise the local humidity around each other.

Setting Up a Winter Mushroom Grow Tent or Room

Long before Out-Grow had a warehouse fruiting room, I ran my winter grows out of a bedroom closet with a clear plastic tote, a cheap ultrasonic humidifier from a drugstore, and a thermometer I checked probably too many times a day. It was not elegant, but it held humidity fine, and it is honestly not that different from what I would still tell a beginner to build today.

You do not need much equipment to grow mushrooms in winter, and you do not need to heat a whole room to tropical levels. What helps most is a small enclosed fruiting space, a way to hold humidity, and a hygrometer so you are managing real numbers instead of guessing. A heater is useful only if your grow area drops below the fruiting range, and even then, warming the room evenly beats any point source of heat. Here is the setup in order.

Lighting is the one place beginners overspend in winter. Mushrooms do not photosynthesize, so light is a directional and developmental cue, not an energy source. An ordinary room light or a small LED on a 12 hour on and 12 hour off cycle is plenty. Skip the expensive plant grow lights and put that money toward a humidifier and a decent hygrometer instead.

If you want the shorter version of that list before you start, here is what actually needs to be in place.

Collapsed down, the whole winter sequence is really just three phases repeating on a loop.

Growing Oyster, Shiitake, and Enoki Mushrooms in Winter

One winter I moved a tray of pinning enoki out to an unheated mudroom just to see what the cold actually did to them, since I had read that a hard chill during cap development tightened the clusters. Within about four days the stems on that tray were noticeably firmer and closer together than the ones I had left in the main fruiting room at the warmer end of the range. It was a small test, but it convinced me the cold finish is worth the extra step.

Each of the top three winter species has its own trick, and knowing them turns cold weather into a tool. These are the moves I point growers to when they want mushrooms on the counter in the dead of winter.

Enoki takes the opposite strategy from those dormant outdoor logs. Instead of waiting out the cold, it is actively fruited in it.

Common Bad Advice About Growing Mushrooms in Winter

A mushroom forum thread I read last winter had more than forty replies arguing about whether to run a space heater under a fruiting tub to keep the cold out. Almost nobody in that thread mentioned humidity at all. That thread is a pretty good snapshot of where winter advice usually goes wrong, so here are the specific claims worth correcting.

Winter advice online is full of confident rules that quietly cause the failures they claim to prevent. Here are the ones worth unlearning.

"You cannot grow mushrooms once it is cold." This is simply wrong. Extension guides and commercial growers describe winter cultivation every year, and several species prefer cool conditions. Indoors you can grow all winter, and outdoors the cold hardy species carry the mild and shoulder seasons.

Many beginner guides claim heat matters more than humidity in winter. It is the reverse. Dry heated indoor air is the main reason winter grows stall, not the temperature. High humidity, around 85 to 95 percent for fruiting, matters far more than chasing a perfect number on the thermometer. Solve humidity first.

A common rule you will see is to seal your tub or tent tight in winter to hold in heat. Sealing the space to trap warmth starves the grow of fresh air exchange, and the carbon dioxide the mycelium exhales builds up fast. The result is long, leggy stems, fuzzy feet, and stalled pins. Fresh air exchange still has to be balanced against humidity in winter. Do not trade it away for a couple of degrees.

Another popular tip is to put a heat mat under the tub or block. Point source bottom heat tends to overheat and dry the substrate right where the roots are working, and it can cook a colonizing block. If you need warmth, heat the room evenly and gently instead of blasting one surface.

Some guides say you need strong grow lights in winter like houseplants. Mushrooms are not plants and do not use light for energy. A simple 12 hour on and 12 hour off cycle of ordinary ambient or low intensity LED light is all they need to orient and develop.

Relevant Out-Grow Supplies for Winter Mushroom Growing

Every November the same handful of items start moving faster out of the Out-Grow warehouse: hygrometers, small humidifiers, and cold tolerant liquid cultures like blue oyster and enoki. That seasonal shift in what people actually order is a decent proxy for what a winter grow really needs, and it lines up with what I would recommend anyway.

These are the supplies that genuinely match a winter grow, with honest notes on where each one fits.

• Gold enoki liquid culture. Enoki is the classic winter mushroom and fruits at temperatures that stall most species, so it is the natural pick if you have a genuinely cold spot to work with.
• Blue oyster liquid culture. Cold tolerant, fast, and forgiving, blue oyster is the easiest way to keep mushrooms coming through a cool winter room. Grey oyster strains behave similarly.
• All in one grow bags. The lowest effort winter starter. You colonize warm and fruit cool in the same bag, which is ideal when you are short on space and setup time.
• Mushroom grow bags. For building your own winter grows with the right filter for gas exchange while the substrate stays clean.
• Mushroom supplies. Where to find the hygrometer and humidity gear that make the difference in dry, heated winter air.

If you want to browse cultures beyond these two, the full range of liquid culture options covers plenty of other cool weather friendly species.