A beginner’s guide to growing and experimenting with Physarum polycephalum

The Blob is a living, moving organism. It has no brain, muscles or nervous system, but it can explore spaces, find food, build networks and respond to its environment. It is not a fungus, plant or animal. Think of it as a living material you can collaborate with.

1. What you need

• A living Blob or dried sclerotium (sleeping Blob)
• Petri dishes or clean plastic containers with lids
• Filter paper or a thin layer of 1% agar.
• Sterilised oat flakes
• Clean water, a pipette or spray bottle, and tweezers
• A dark box or cupboard
• Optional: camera, food colouring, multimeter, electrodes, Arduino

2. How to grow your Blob

Basic conditions: 20–25°C, darkness, a moist surface and no standing water.

Option A — On filter paper

1. Cut filter paper to fit a 90 mm Petri dish.
2. Add water, just enough to make the paper fully wet. Remove excess water.
3. Place a small piece of dried Blob (around 5–10 mm) in the centre. And revive it with a few drops of water.
4. Once the blob starts moving place 1–2 small oat flakes about 1–2 cm away.
5. Close the lid and keep at 20–25°C in darkness.
6. Check every 24 hours. Add food when the previous oats have mostly been consumed and clean up waste.

Option B — On agar

1. Mix 1 g plain agar powder with 100 mL water (1% agar).
2. Heat until dissolved. Pour approximately 15–20 mL into each 90 mm Petri dish.
3. Let it cool and solidify completely.
4. Place a small piece of Blob in the centre and hydrate it with a few drops of water. Once it starts moving give it 2–4 oat flakes nearby.
5. Close the lid and keep at 20–25°C in darkness.
6. Check daily. Move a small piece to fresh agar every 5–7 days.

3. Tips & tricks

• Wet, not flooded: Too much water can damage the Blob.
• Keep it dark: Strong light can stress it or trigger reproduction.
• Don’t overfeed: Old oats can develop unwanted mould.
• Make backups: Keep a second culture in case one fails.
• Photograph regularly: A photo every 10–30 minutes can become a timelapse where you can see it move.
• Make it sleep: Stop feeding for 2 days while keeping it moist, then slowly dry it over 2–3 days. Allow another 1–2 days to mature.
• Keep it clean: Use clean tools, wash your hands and keep cultures covered.

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