How to Grow Wood Ear Mushrooms on Logs and Sawdust

Wood ear, also called black fungus, cloud ear or jelly ear (Auricularia species), is one of the most widely farmed mushrooms in the world. Few home growers try it, though. It has no cap, no gills and no stem: just rubbery, ear-shaped brown or black jelly that grows from wood and dries to a fraction of its size. That unusual biology means it is grown a little differently from oyster or shiitake, and it rewards patience.

This guide explains the main routes for growing wood ear at home: outdoor logs, and indoor sawdust bags. It also covers drying and rehydrating your harvest, and a little-known food-safety rule about soaking dried wood ear that every grower and cook should follow.

A quick introduction to Auricularia

Several Auricularia species are cultivated. A 2023 paper in Studies in Fungi by Walker and colleagues lists A. heimuer and A. polytricha as commercially grown in China. It adds that A. cornea and A. heimuer are grown for sale across China and South-East Asia, and that Thailand’s commercial growers have used A. auricula-judae and A. polytricha. The same paper cites figures showing that China produces more than 90% of the world’s wood ear, with 674,000 tonnes of dried product in 2018. It also notes that wood ear has been cultivated in China for around 2,100 years.

For home growers, the important point is that spawn may be sold under any of these names. Species differ in their preferred temperatures, so match your growing conditions to the species and strain you buy. For more on the mushroom itself in the kitchen, see our wood ear guide.

Choosing your method

	Outdoor logs	Indoor sawdust bags
Difficulty	Easy to set up, slow to start	Harder: needs sterilisation and steady humidity
Substrate	Freshly cut hardwood logs, with oak recommended	Hardwood sawdust with bran
Time to first harvest	Often 8 to 12 months or more to colonise	Roughly 3 to 5 months after inoculation in the sources below
Fruiting trigger	Rain and mild, cool weather	High humidity, light and a cooler room
Best for	Gardens with shade and regular rain	Growers already used to sterile sawdust blocks

Option 1: Wood ear on logs

Mushroom Mountain, a US spawn supplier, recommends oak for wood ear logs, though other healthy hardwoods may also work. The process will be familiar if you’ve grown shiitake on logs:

Cut fresh logs from healthy hardwood trees.
Drill holes in a diamond pattern along each log.
Insert plug spawn, one plug per hole, or pack the holes with sawdust spawn.
Seal each hole with wax to keep moisture in and competing fungi out.
Stack the logs in a shaded, humid spot outdoors.

What you’ll need for logs

Freshly cut hardwood logs, ideally oak
Wood ear plug or sawdust spawn
A drill and bit to match your spawn, plus an inoculation tool if you’re using sawdust spawn
Food-grade wax and a dauber or brush
A shady, sheltered spot where you can water the logs in dry weather

Not sure whether logs or bags suit you better? Our comparison of log growing and bag growing sets out the trade-offs in cost, effort and yield.

Colonisation and fruiting

Mushroom Mountain says outdoor logs commonly take about 8 to 12 months or longer to colonise. During that time, keep the wood consistently moist and protect it from drying out for long periods. Once established, wood ear fruits best at around 50 to 70°F (10 to 21°C), in cool to mild weather. It often fruits after periods of rain. Well-kept logs may keep producing for several seasons.

Moisture is the main lever. Because fruiting so often follows rain, outdoor logs do best somewhere naturally damp, and watering or soaking them during dry spells helps keep them productive.

Several reddish-brown wood ear fungi fruiting from the bark of a tree trunk — Wood ear fruiting from tree bark. Photo: geoffWCNR via iNaturalist, CC0 1.0.

Option 2: Indoor sawdust bags

Most commercial wood ear is grown on sawdust. Walker and colleagues note that sawdust is typically the main substrate, with agricultural waste used in parts of South-East Asia to keep costs down. Indoor growing is more demanding than logs, because supplemented sawdust must be sterilised and the bags need high humidity for weeks.

What the research and suppliers report

Source	Substrate	Colonisation	Fruiting conditions
Walker et al. 2023 (A. cornea, Thailand)	Rubber-tree sawdust with rice bran and other supplements, 800 g bags	60 days at 25°C in darkness	25°C, 75 to 85% humidity
Thongklang and colleagues (wild A. cornea strain, Thailand)	Rubber-tree sawdust bags	Not stated	25°C, 75 to 85% humidity
Root Lab (A. auricula-judae culture)	80% sawdust and 20% bran, sterilised	About 25 to 30 days at 23°C	10 to 21°C, very high humidity, more than 1,000 lux of light

The differences reflect the species. A. cornea strains from tropical Thailand fruit at warm temperatures. Temperate A. auricula-judae prefers cooler conditions. Root Lab even advises staying at the lower end of its range, and suggests a cold shock if the bags won’t fruit. Its product page has some inconsistent figures, so treat them as a rough guide and follow the instructions supplied with your culture.

Step by step

Prepare the substrate. Mix hardwood sawdust with bran (Root Lab suggests 80:20), hydrate it, and bag it in filter-patch grow bags.
Sterilise. Use a pressure cooker or autoclave. Pasteurisation is not enough for supplemented sawdust. Our article on sterilisation versus pasteurisation explains why.
Inoculate and incubate. Add grain spawn or liquid culture under clean conditions, then keep the bags in darkness at the temperature your species prefers until they are fully colonised.
Cut fruiting holes. Root Lab describes wood ear as fruiting from the side, so make small cuts or X-shaped slits in the sides of the bag rather than opening only the top.
Fruit with humidity and light. Keep humidity very high, and give the bags more light than many other species need. Root Lab warns that too little light is a common mistake.
Be patient. In the Walker study, the first primordia appeared 15 to 26 days after fruiting began, and harvests came about 28 to 35 days into fruiting. Root Lab says a full fruiting cycle can take up to 4 to 5 months.

Yields

Published yields vary widely. Walker and colleagues recorded 19.4 to 31.0 g per bag from the first flush, depending on the strain. Thongklang and colleagues reported an average of 242 g over six flushes in three months, a biological efficiency of about 72%. Biological efficiency is the fresh weight of mushrooms divided by the dry weight of the substrate. A study cited by Walker reported 288.9% for A. polytricha on sawdust supplemented with oil palm fronds and spent grain. As with most species, strain and substrate make a large difference.

Harvesting and drying

As a general rule, harvest wood ear when the “ears” have fully expanded but are still soft and flexible. Twist or cut them off at the base. Because the fruit bodies are mostly water, they shrink dramatically when dried. Spread them in a single layer somewhere warm and airy, or use a food dehydrator, until they are hard and brittle. Store them in an airtight container.

Food safety: how to soak dried wood ear

This is the most important section for anyone who eats wood ear. Hong Kong’s Centre for Food Safety (CFS) has warned about bongkrekic acid, a heat-resistant toxin produced by the bacterium Burkholderia gladioli pathovar cocovenenans. According to the CFS:

Outbreaks in Guangdong and Zhejiang provinces were linked to black fungus (wood ear) and silver ear fungus that had been soaked for more than two days.
Symptoms can appear between 30 minutes and 12 hours after eating, and severe cases can be fatal. Past outbreaks in mainland China had death rates of up to 60%.
The toxin is not generally expected to form when the mushrooms are soaked for a short time under normal conditions.
If you need to soak black fungus overnight, the CFS says to do it in the refrigerator.

So: rehydrate dried wood ear for a short time in clean water, refrigerate it if it must soak overnight, and never leave it soaking at room temperature for days. Because the toxin resists heat, cooking will not make over-soaked wood ear safe. If you’re not sure how long something has been soaking, throw it out.

Wild wood ear and identification

Wood ear grows wild in many regions, often on dead branches. The photos in this article show wild A. auricula-judae in the UK. Several other jelly fungi also grow on wood, and wild fungi always carry identification risks. If you want to forage, learn the species in person from an experienced local identifier first, and never rely on a photo or description alone. Growing from purchased spawn avoids the problem.

Troubleshooting

Fruit bodies dry, hard or curled on the log: it’s too dry. Water or soak the logs, and expect better fruiting after rain.
Bags fully colonised but not fruiting: the light may be too low or the temperature may be wrong for the species. Increase the light, and for temperate strains try a cooler room or a cold shock.
Green or black mould in bags: this is contamination, usually from incomplete sterilisation or unclean inoculation. Remove the bag from your growing area.
Logs slow to produce: 8 to 12 months or more is normal. Keep them moist and shaded.

For a different log-grown species with cool-weather fruiting, see our guide to growing nameko.

Sources and further reading

Featured image: wood ear by Charles Joynson via iNaturalist (CC0 1.0). Inline photo by geoffWCNR via iNaturalist (CC0 1.0).

How to Grow Wood Ear Mushrooms on Logs and Sawdust (and Soak Them Safely)

A quick introduction to Auricularia

Choosing your method