Oyster Mushroom Grow Guide
This guide is designed for all oyster mushroom varieties we offer at DuraFungi — whether you're growing White Oyster, Grey Oyster, or Blue Pearl Oyster. Your block has already given you a beautiful first harvest – now let's help it produce a generous second and even third flush with simple, repeatable steps.
What You'll Need Before You Start
- Clear container or "mushroom tent": Use everyday household items to create a simple humidity tent. For example, place wooden skewers or chopsticks around the block and drape a clear plastic bag or plastic wrap over the top, leaving small gaps for airflow. You can also use a transparent storage tub or glass baking dish with a loose clear cover. The key is that you can see the block easily.
- Fine spray bottle: A small, fine-mist bottle filled with clean water. If using tap water, let it sit uncovered for 24 hours or boil and cool it first to reduce chlorine.
- Sterilised scissors or small knife: For making or enlarging small cuts ("X" or slit) in the grow bag when needed. Wipe the blade with rubbing alcohol or boiling water before use.
- Clean hands or gloves: Helpful for harvesting and handling the block without introducing contaminants.
- Optional helpers: A small tray or plate under the block to catch drips, plus a bowl of hot water or a small fan nearby if you need to fine-tune humidity.
Materials Q&A – Oyster Blocks
Do I need a special container for my oyster block?
No special equipment needed. Any clear household container works as long as it lets you create a humid "tent" and you can easily see the block. Skewers + clear plastic wrap, a transparent storage tub, or a glass dish with a loose clear cover are all fine.
Why do I need a fine spray bottle?
Oyster mushrooms like gentle humidity, not heavy water droplets. A fine mister lets you moisten the air and surface around the block without soaking the caps or gills, which helps prevent sliminess or damage.
Do I really have to sterilise my scissors or knife?
It's strongly recommended. A quick wipe with rubbing alcohol or a pour of boiling water over the blade helps reduce bacteria and mold. It's an easy step that protects the block over multiple flushes.
Why can't I just use ordinary tap water?
You often can use tap water, but many supplies contain chlorine. Letting water sit for 24 hours or boiling and cooling it first allows chlorine to dissipate. This gives your oyster mycelium a friendlier environment, especially if your local water is heavily treated.
Is it okay to use rainwater instead of tap water?
Yes — clean rainwater is excellent for oyster mushrooms. Just make sure it's collected from a clean source (e.g. tank or container without debris). It's naturally chlorine-free and very mushroom-friendly.
Instruction Video – Oyster Mushroom Grow Block
Prefer to follow along visually? This step-by-step video shows how to set up your oyster mushroom block, create a humidity tent, and care for it through each flush.
Setup & First Flush Overview
Step 1 – Set Up Your Grow Block
Place your fruited block into your clear container or mushroom tent. Leave a little space around the block so air can move. Keep it in a cool, bright, well-ventilated area out of direct sunlight.
Step 2 – First Flush Harvest Check
Your oyster mushrooms are ready when the caps are wide and fan-shaped, and the edges are just starting to curl slightly upwards. At this stage they're tender, aromatic, and perfect for cooking.
Complete Grow Guide
Daily Care: Misting & Environment
-
Misting Around the Block
Use your fine spray bottle 2–3 times per day. Mist the air and surfaces around the block, not directly into the gills or caps, until inside the tent feels humid but not dripping.
The goal is a lightly moist environment. If you see water pooling on the block or container, reduce misting.
-
Temperature & Light
Oyster mushrooms prefer 18–24 °C. Avoid strong heating, air-conditioning or freezing drafts. They also need indirect light for 8–12 hours a day – a naturally bright room is perfect.
-
Fresh Air
Open the tub or lift the tent once or twice a day for a few minutes to let fresh air in. This helps prevent long, thin stems and encourages dense, meaty clusters.
Harvesting Your First Flush
When your cluster looks ready (wide caps, edges curling slightly upward), it's time to harvest.
-
Check for Readiness
Try not to leave them until the caps are very flat or dropping lots of white spores — that's a sign they're going past their best eating stage.
-
Harvest Technique
With clean hands (or gloves), hold the base of the cluster firmly and gently twist and pull the entire cluster off the block in one go.
-
Prepare the Block for Rest
After harvesting, brush away any loose mushroom pieces and get ready for the second-flush routine below.
Getting a Second (and Third!) Flush – Full Cycle
Step 1 – Clean & Rest (3–5 Days)
After your first harvest:
- Clean off any dried or leftover mushroom pieces from the harvest site.
- Mist the harvest area lightly to re-moisten the surface.
- Fold the plastic flap back over the opening and tape lightly to close.
- Let the block rest in a cool, shaded spot (laundry or bathroom) for 3–5 days.
Step 2 – Soak to Rehydrate (3–4 Hours)
When the rest period is over:
- Submerge the entire plastic-wrapped block in cold water for 3–4 hours.
- Use a weight (plate or bowl) to keep it underwater.
- Remove and drain thoroughly so no standing water remains in folds of the plastic.
Step 3 – Reseal & Rest Again (5–7 Days)
Fold the plastic flap back over, tape closed again, and let the block rest for another 5–7 days. This allows the moisture to spread evenly through the substrate.
Step 4 – Create a New Fruiting Site
After the second rest, look for tiny white pins forming. If none appear after 5–7 days, make a shallow new "X" or slit on a different side of the block using your sterilised scissors or knife.
Never reuse the original hole – a fresh opening encourages a stronger new flush.
Step 5 – Misting, Airflow & Light
- Mist the exposed substrate only – 4–5 light sprays, 2–4 times per day.
- Tilt the block about 45° or use a wedge so air can move around the new fruiting site.
- Provide 8–12 hours of indirect light and 5–10 minutes of gentle fresh air daily (outside in a shaded spot is fine).
- A new flush usually appears in 7–14 days – then repeat for a third flush if the block still has energy.
Storing Your Harvested Oyster Mushrooms
For best flavour and texture, store your mushrooms carefully:
- Wrap clusters in a paper towel and place them in the fridge crisper (around 2–4 °C).
- Change the paper towel every 2 days to remove excess moisture.
- Use within 5–7 days for peak quality.
Mistake Recovery
Too wet?
Caps look slimy or waterlogged? Use a hairdryer on cold setting for around 2 minutes, blowing gently across the caps to dry the surface.
Too dry?
If your home is very dry, boil a kettle nearby and use a small fan in the room (not pointed directly at the block) to gently circulate the warm, moist air. Increase misting slightly until the block feels evenly moist again — not soggy.
Oyster Mushroom DOs & DON'Ts
DO
- Use a fine mister, not a heavy spray.
- Tilt the block for better airflow around the fruiting site.
- Inspect for new pins before cutting a new slit.
- Keep the block in non-air-conditioned, naturally humid areas where possible.
DON'T
- Don't soak the mushroom caps directly when misting.
- Don't place the block in direct, hot sunlight.
- Don't reuse the first X-cut – always choose a fresh side.
- Don't refrigerate the growing block itself – only the harvested mushrooms.
Need Help or a Virtual Guide?
If you're unsure about what you're seeing on your block, we're happy to help – including quick video checks.
Text or call us on 0477 008 037.
Taste the difference in sustainable choices made — one mushroom at a time.
— The DuraFungi Team
Sustainably grown in South Australia
durafungi.com · @DuraFungi