How to grow wine cap mushrooms in a garden wood chip bed

Wine cap, Stropharia rugosoannulata, is the mushroom for gardeners. It grows outdoors in a bed of wood chips, it fits between vegetables and under fruit trees, and it needs no grow tent or humidifier. Cornell Small Farms calls it one of the easiest mushrooms for beginners. It also goes by king stropharia and garden giant, because the burgundy caps can reach the size of a dinner plate.

This guide covers the full project. You will turn a liquid culture syringe into enough spawn for a bed, build the bed, care for it, identify and harvest the mushrooms, and keep the bed producing for years.

Why grow wine caps

Wine caps break down wood chips and straw, so they fit into a garden you already mulch. Brooklyn Botanic Garden suggests planting them under tomatoes, around fruit trees, or in perennial beds. North Spore notes that wine caps tolerate more sun than most cultivated mushrooms, which makes them a good fit for vegetable gardens.

A bed needs only a few square feet. Brooklyn Botanic Garden reports that a bed keeps fruiting for about three years, and a top-up of fresh chips each year keeps it going.

From liquid culture to bed spawn

You cannot squirt a liquid culture onto wood chips and expect a crop. Outdoor chips are full of other fungi and bacteria, and 10 ml of culture is far too little to claim a bed. Wine cap mycelium needs a head start on clean grain before it goes outside. A liquid culture gets there fast. GroCycle notes that its living mycelium starts colonizing grain right after you inject it.

You also need a lot of spawn. Savvy Gardening’s rule of thumb is about 1 pound of sawdust spawn for every 9 to 10 square feet of bed. A 4 by 4 foot bed, about 16 square feet, needs roughly 2 pounds.

Here is the path from syringe to bed:

1. Prepare the syringe. Let a refrigerated syringe warm to room temperature, then shake it. The broth should be clear with white to cream wisps that settle.
2. Inject the grain. In a still air box wiped down with 70% isopropyl alcohol, wipe each injection port with the alcohol pad. Inject 1 to 3 ml into each quart jar of grain sterilized at 15 PSI for 90 minutes, or 2.5 to 5 ml into each grain bag. North Spore uses 2.5 ml per injection port bag. GroCycle reports that jars fully colonize in about 2 to 3 weeks.
3. Expand the grain. Once a jar is solid white, use it to inoculate more sterilized jars or bags. Keep expanding until you have the 2 pounds or so your bed needs.

You can put one drop of culture on an agar plate before step 2 to check purity, but it is optional. Throw out any jar with colored mold, slimy grain, or a sour smell. Store the rest of the syringe in the fridge, never freeze it, and use it within the window on the product page.

Never use an open flame inside a still air box. North Spore warns that trapped alcohol vapor can ignite. If you reuse the needle, flame it red hot outside the box and let it cool before you bring it in.

Plan the lab work around your planting date. Two rounds of grain at 2 to 3 weeks each take four to six weeks, so start in late winter for a spring bed.

Choose a site and materials

Brooklyn Botanic Garden recommends partial shade. Wine caps tolerate more sun than many mushrooms, but a spot that gets afternoon shade from a tree or tall crops keeps the bed from drying out.

For the bed itself, gather:

• Fresh hardwood chips. Brooklyn Botanic Garden and Savvy Gardening both recommend freshly cut chips, so other fungi have not already moved in.
• Straw, if you want. Savvy Gardening notes that straw colonizes fastest but fruits for a shorter time, while chips keep a bed going longer. Savvy Gardening and Tilth Alliance both mix the two.
• Plain cardboard. It is optional, but it smothers weeds under the bed.

Savvy Gardening suggests soaking the chips well and letting them drain before you build.

When to plant

Brooklyn Botanic Garden plants from the last spring frost until a few weeks before the first fall frost. Savvy Gardening calls spring the best time, because the mycelium has the whole season to establish. Avoid planting just before winter.

Build the bed

North Spore and Brooklyn Botanic Garden both build the bed in layers, like a lasagna:

1. Clear the area down to bare soil. Remove weeds, debris, and old mulch.
2. Lay down cardboard if you are using it.
3. Spread about 2 inches of chips.
4. Crumble spawn evenly over the chips.
5. Repeat the chip and spawn layers until you run out of spawn or the bed is 6 to 8 inches deep.
6. Finish with a top layer of chips. North Spore notes that this layer shields the spawn from sun and drying wind.
7. Water the whole bed thoroughly.

North Spore adds that deeper beds may produce longer but take longer to colonize before they fruit.

Water and wait

Water is the main job for the first month. North Spore recommends watering the bed like a vegetable patch for at least the first four weeks, with a deep soak about every other day. The bed should stay moist but never waterlogged. Brooklyn Botanic Garden’s test is to push a finger a few inches into the chips. They should feel damp, not wet.

After a few weeks, dig gently just below the surface. You should see white, ropy strands of mycelium threading between the chips. That tells you the bed is taking hold.

Cornell Small Farms reports that wine caps fruit 2 to 6 months after inoculation, as long as temperatures stay warm enough. North Spore lists fruiting from spring through fall when temperatures run about 50 to 70°F. Mushrooms often pop up after a good rain. In a Seattle community garden bed described by Tilth Alliance, August rain and cooler nights brought the first flush about three months after planting.

How to identify wine caps

Other mushrooms can appear in any wood chip bed, so learn wine caps well. North Spore lists these features:

• Cap. Deep burgundy to wine red when young, fading to tan or brown in sun. Young caps often have white tufts near the edge.
• Gills. Purple-gray when young, darkening to purple-brown as the spores mature.
• Stem. White to cream.
• Ring. A thick ring on the stem with a split, cogwheel-like edge.

Brooklyn Botanic Garden adds that mature wine caps drop dark spores that show up as dark dust on the stem and on the chips below.

Eat only mushrooms that match every one of these features. If anything in the bed looks different, leave it alone.

Harvest at the right stage

Check the bed every day or two once it starts fruiting, especially after rain. Brooklyn Botanic Garden recommends harvesting within a few days of the mushrooms appearing. Savvy Gardening says the best flavor comes before the veil under the cap breaks open. Younger mushrooms also have more tender stems.

Twist or cut each mushroom at the base. Past-prime wine caps have broken veils, faded or cracked caps, and yellowed stems, and insects find them quickly. After a flush, Tilth Alliance reports that beds usually rest for 3 to 4 weeks before the next one.

Cooking wine caps

Brooklyn Botanic Garden describes the flavor as mild and vegetal. Savvy Gardening compares young caps to cashews, with a meaty texture. Always cook wine caps thoroughly. Brooklyn Botanic Garden warns that raw or barely cooked mushrooms carry a risk of food poisoning.

Sauté them in butter with garlic and salt, roast them, or add them to pasta, soups, and braises. The first time you eat them, Savvy Gardening suggests starting with a small portion.

Keep the bed going

A wine cap bed is a multi-year crop. Each year, add a few inches of fresh chips on top so the mycelium has new food. At the end of the season, Tilth Alliance mulches its bed heavily with straw, chips, twigs, and leaves to carry it through winter.

You can also spread the patch. Brooklyn Botanic Garden suggests digging up a shovelful of established mycelium and using it to start a new bed elsewhere in the garden, and Cornell Small Farms notes that an established patch can seed new ones.

Start your wine cap bed

A wine cap bed is a good first outdoor project, and it turns your wood chip mulch into a food crop. Our wine cap liquid culture comes as a 10 ml luer-lock syringe with a sterile needle and an alcohol prep pad, ready to inject into grain. While you wait for the bed to fruit, you can practice the same lab skills indoors with blue oyster liquid culture. Browse every variety in our shop.