How to grow Oyster Mushroom in New Zealand
Oyster mushrooms are the easiest gourmet mushrooms to grow at home. They grow on straw, sawdust, used coffee grounds, cardboard or hardwood rather than soil, and a ready-made kit can produce its first clusters of soft, fan-shaped caps within a few weeks. They are an indoor or sheltered crop you can grow all year, as long as you keep them moist, shaded and in fresh air.
📖 Our full guide: How to Grow Oyster Mushroom in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | All year | |
| Auckland | All year | |
| Waikato & Bay of Plenty | All year | |
| Central North Island | All year | |
| Wellington & Lower North Island | All year | |
| Nelson & Marlborough | All year | |
| Canterbury | All year | |
| Otago & Southland | All year | |
| Central Otago | All year |
Where to plant
Oyster mushrooms need a spot away from full sun with steady, mild temperatures, high humidity and plenty of fresh air: a laundry, a shaded corner of a kitchen, a garage with some light, or a sheltered, shady spot outdoors in mild weather. They need some light to form proper caps, but direct sun dries them out.
Fresh air matters as much as moisture. In a stuffy, enclosed space the mushrooms grow long, thin stems with small caps, and the growing medium is more likely to go mouldy.
- All regions: oyster mushrooms are grown indoors or under cover, so they can be grown anywhere in New Zealand all year. Grey oysters fruit best in mild conditions, so in summer keep kits in the coolest shady room, and in winter in a room that stays above about 15°C.
- Buy kits and spawn from New Zealand suppliers. Importing live fungal cultures is controlled by biosecurity rules.
Choosing a variety
| Type | Notes |
|---|---|
| Grey oyster (Pleurotus ostreatus) | The easy beginner oyster, grown on straw, coffee grounds or cardboard, with reliable repeat flushes in mild conditions |
| Pink oyster | Fast, vivid pink clusters that like warmth; best fruited in the warmer months indoors |
| King oyster (Pleurotus eryngii) | Thick, meaty stems; usually grown from kits or prepared blocks |
How to plant
- The simplest start is a ready-made kit: a bag or block of substrate already colonised by oyster mycelium. Follow the kit instructions, usually opening or cutting a slit in the bag where the mushrooms will grow.
- Place the kit in bright, indirect light in a mild spot with good air movement.
- Mist the opening once or twice a day to keep it humid, without leaving the block sitting in water.
- Tiny mushroom pins appear within a week or two and grow quickly into clusters.
- To grow your own on straw or coffee grounds, mix fresh spawn into pasteurised straw or fresh used grounds in a bag with air holes, keep it dark and warm until it turns white with mycelium, then move it into light and humidity to fruit.
Watering and feeding
Keep the surface humid by misting once or twice a day while mushrooms are forming; the caps should feel moist but not wet or slimy. In dry, heated rooms a loose plastic tent over the kit, opened daily for fresh air, helps hold humidity.
Oyster mushrooms need no fertiliser; all their food comes from the substrate. Between flushes, let the block rest for a week or two, then soak it briefly in cool water if it feels light and dry, and start misting again.
Pruning and care through the year
- Give fresh air daily. Long, thin stems and small caps mean the air is too stale.
- Remove any part of the block that grows green, black or pink mould, or discard a badly contaminated kit.
- When a block stops producing, break it up into the compost heap or under mulch in a shady garden bed, where it may produce a few more mushrooms.
Harvesting
Harvest the whole cluster when the caps have opened out but before their edges start to flatten, curl upward or turn papery. Twist the cluster off at the base or cut it with a sharp knife, close to the block.
Oyster mushrooms are best eaten fresh. Store them in a paper bag in the fridge and use them within a few days, and always cook them before eating.
Pests and diseases
Most problems with oyster mushrooms come from contamination and stale air rather than pests.
Pests to watch for
- Fungus gnats Tiny dark flies around the block and small larvae in the mushrooms. Harvest promptly and keep the area clean.
Diseases to watch for
- Mould contamination Green, black or pink mould on the block instead of white mycelium, often with a sour smell. Usually from dirty substrate or too little fresh air; discard badly affected blocks.
Common questions
How long do oyster mushroom kits take to fruit?
Usually two to four weeks after opening the kit, depending on temperature. Small pins appear first and grow into clusters within days.
Why are my oyster mushrooms long and thin?
They need more fresh air, and sometimes more light. Move the kit somewhere with better air movement and bright, indirect light.
How many times will a kit fruit?
Usually several flushes, about every two to three weeks. Rest the block between flushes, rehydrate it if it feels light, and keep misting.
Can I grow oyster mushrooms on coffee grounds?
Yes. Fresh used coffee grounds mixed with oyster spawn in a bag with air holes can be colonised and fruited at home, though it takes more care than a ready-made kit.
When should I pick oyster mushrooms?
When the caps have opened out but before the edges flatten, curl or turn papery. Twist off the whole cluster at the base.
Sources we checked: Tui: Mushroom growing guide; Wikipedia: Pleurotus ostreatus (oyster mushroom); Wikipedia: Fungiculture (indoor oyster mushroom farming).