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How to Grow B+ Mushrooms: Big Caps, Few Surprises
How to grow B+ mushrooms is a short story: keep a colonized kit at 23 to 25 °C in bright indirect light, leave the bag closed until pins appear and then add fresh air once to three times a day. B+ is one of the most forgiving Psilocybe cubensis strains and is known for large mushrooms, with caps of 3 to 10 cm, so the main skill is timing the harvest.
What makes B+ different from other cubensis strains?
B+ stands out for size and tolerance. The Mondo strain library describes it as easy to grow, with large caps, thick stems and good adaptability to different conditions. Its exact origin is unknown; it is a strain from modern cultivation rather than a named wild collection.
| B+ | Golden Teacher | |
|---|---|---|
| Difficulty | Easy | Easy |
| Colonization | 10 to 20 days | 10 to 20 days |
| First harvest | About 2 to 3 weeks | About 2 to 3 weeks |
| Flushes | 2 to 4 | 2 to 4 |
| Cap size | 3 to 10 cm | 2 to 8 cm |
| Cap color | Light caramel to golden brown | Golden brown to yellow |
In practice B+ and Golden Teacher are both good first strains. B+ tends to produce fewer, larger mushrooms; Golden Teacher a more mixed flush. Our Golden Teacher grow guide covers the week-by-week routine that applies to B+ as well.
Which conditions does B+ like?
B+ likes the standard conditions from the Mondo grow kit manual and tolerates small deviations better than most strains:
- Temperature: 23 to 25 °C ideal, below 27 °C. B+ usually keeps growing at 21 to 22 °C, just more slowly.
- Light: bright, indirect. No direct sun on the bag.
- Humidity: keep the bag closed until pins appear; droplets on the inside are normal.
- Fresh air: brief air exchange 1 to 3 times a day once pins appear.
Its tolerance is useful in a house where the temperature varies between day and night, but tolerant is not the same as indestructible. A kit at 19 °C will still be slow.
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When should you harvest B+ mushrooms?
Harvest B+ when the veil under the cap starts to tear, just as with other cubensis strains. Because B+ caps grow large, it is tempting to wait for them to get even bigger. That usually backfires: once the veil is gone and the cap flattens, the mushroom starts dropping spores and adds little weight.
Signs a B+ mushroom is ready:
Twist large B+ mushrooms carefully at the base. Their thick stems can pull up a piece of substrate if you yank them. If a mushroom sits tight, cut it close to the surface with a clean knife instead. See how to harvest magic mushrooms for both techniques.
Watch the biggest mushroom first
In a B+ flush, the largest mushrooms often mature first. Check those every morning and evening once caps start to separate from the stem, and harvest them individually if the rest of the flush is still growing.
How do you get more flushes from B+?
After the first harvest, remove all remaining pins and stems, soak the kit as described in the manual and put it back in the same spot. B+ usually gives two to four flushes. Each one tends to be smaller, and the gap between flushes can get longer as the substrate runs out of water and nutrients. The flushes guide explains how to prepare the kit for each round.
What can go wrong with B+?
Most B+ problems come from the same few causes as with any cubensis kit:
- Long, thin stems with small caps: too little fresh air, so carbon dioxide builds up. Air the bag a little more often.
- No pins after two weeks: usually too cold or too dark. Check the temperature on the kit itself.
- Dark, stalled pins: often a drop in humidity or temperature just after pinning. See aborted mushroom pins.
- Green or black patches: possible contamination. Keep the bag closed and compare with our contamination guide.
Grow B+ with Mondo
Every Mondo product comes with a step-by-step manual on our site, and orders ship discreetly with tracking.
View the B+ grow kitQuestions about growing B+
Yes. B+ is rated easy in the Mondo strain library and tolerates small mistakes well, which makes it one of the best first strains next to Golden Teacher.
Large caps and thick stems are typical for B+. A stable temperature and good humidity make them even more pronounced.
Not more than other cubensis strains, but large mushrooms show the effects of stale air clearly: long stems and small caps. Stick to brief air exchange one to three times a day.
Yes. The B+ Ready-to-Grow Bag XL holds about 2.1 kg of colonized substrate and fruits directly inside its own bag.
Yes. B- is a separate cubensis strain and is available from Mondo as a liquid culture and spore swab. It should not be confused with B+.
