B+ Mushrooms

B+ Grow Kit — The Tallest Fruits in the Range

The B+ grow kit is a fully colonised Psilocybe cubensis cultivation kit that produces some of the largest magic mushroom fruits you can grow at home. Short for "Be Positive," B+ is a mystery strain with unknown origins that has quietly become one of the most widely cultivated cubensis varieties on earth — prized for its forgiving growing requirements and fruits that regularly tower 20–30 cm tall with broad caramel-gold caps. The 1200 ml box ships ready to fruit: colonised rye cake, perlite and vermiculite casing layer, humidity grow bag, and polyfill-filtered air strips. Up to three flushes yield 300–600 g fresh (30–60 g dried) from a single kit.

What Makes B+ Different from Other Cubensis Grow Kits

B+ stands apart on sheer size. Where most cubensis strains in our range produce fruits in the 10–15 cm range, B+ regularly pushes past 20 cm and sometimes hits 30 cm — proper towering mushrooms with thick stems and caps the colour of caramel toffee. They look impressive drying on a rack, and they look even more impressive growing out of the box.

The character leans social and outward-facing rather than deep and introspective. If Golden Teacher is the strain that makes you sit quietly and think about your childhood, B+ is the one that makes you laugh with your mates for three hours. Users consistently call it the "laughing mushroom" — the strain that turns a quiet afternoon into something genuinely warm and connected. Estimated psilocybin content sits around 0.4–0.5% dry weight, which places it slightly below Golden Teacher's 0.4–0.6% range according to available analytical data. According to research published in Molecules (2022), efficient quantification methods for psilocin and psilocybin in fungal samples have enabled more precise strain comparisons (PMC9225378). Effects onset at roughly 45–60 minutes on an empty stomach and typically last 3–5 hours — one of the shorter-duration cubensis experiences.

Compared to Cambodia, which leans energetic and stimulating, B+ keeps things warmer and more relaxed. The headspace stays lucid: enhanced colours, gentle visual textures, and a persistent sense of connection that works well in group settings. For a first-time grower who wants big, photogenic fruits and a cheerful character, B+ is the strain we'd point you towards.

What's in the B+ Grow Kit Box

How to Grow B+ Mushrooms — Step by Step

The B+ strain is famously forgiving, which is partly why it's so popular. Temperature swings that would stall a more sensitive strain barely slow B+ down. That said, a clean setup still matters — we've seen growers lose entire batches to one ungloved hand touching the substrate.

1. Wash your hands thoroughly and wipe down your workspace with a disinfectant. Better yet, wear latex gloves throughout. Contamination is the number one reason grow kits fail, and it almost always comes from the grower, not the kit.
2. Open the box and remove the lid from the grow container. Do not touch the white colonised surface — that mycelium layer is your entire harvest.
3. Fill the container with lukewarm water (20–25°C), replace the lid, and soak for 12 hours. This rehydrates the rye cake and triggers the fruiting process. Set a timer — over-soaking can waterlog the substrate.
4. After 12 hours, drain the excess water by tilting the container gently. Don't shake it or press the substrate.
5. Place the container inside the humidity grow bag. Pour roughly 200 ml of water into the bottom of the bag (not onto the substrate — into the bag around the container). This creates the humid microclimate the mushrooms need.
6. Fold the top of the bag and secure it with the clips or paperclips provided. The polyfill air strips allow gas exchange while keeping contaminants out. Don't seal the bag airtight.
7. Place the kit in a spot with indirect light at 22–25°C. Avoid direct sunlight, radiators, and draughty windowsills. A shelf in a warm room works. B+ tolerates a wider temperature range than most cubensis strains, but 23°C is the sweet spot.
8. Mist the inside of the bag once or twice daily with clean water. You want visible condensation on the bag walls — that's your humidity indicator. If the walls are dry, mist more. If there's pooling water at the bottom, mist less.
9. Pins (tiny mushroom primordia) should appear within 7–14 days. Once pins form, continue misting but avoid spraying the pins directly — aim for the bag walls.
10. Harvest when the caps begin to open but before they flatten completely. The veil underneath the cap will start to tear — that's your cue. Twist and pull gently at the base. Don't cut with scissors, as stumps left behind can rot and invite contamination.

Getting Multiple Flushes from Your B+ Kit

A single B+ grow kit can produce up to 3 flushes, with each flush typically yielding less than the one before. Your first flush is almost always the biggest — expect the bulk of your 300–600 g total from flushes one and two.

After harvesting a flush, remove all remaining mushroom stumps, refill the container with clean water, soak for 12 hours again, drain, and return it to the humidity bag. Pins for the second flush usually appear within 7–10 days. The third flush is often smaller and slower, but B+ is more reliable at producing a proper third flush than many other cubensis strains we carry. If you see green, black, or orange mould at any point, the kit is done — bin it. Don't try to salvage a contaminated substrate.

B+ vs Golden Teacher vs Cambodia — Quick Comparison

We carry several cubensis grow kits, and the question we get asked most is "which one should I pick?" Here's the honest breakdown.

If you want the biggest fruits and a cheerful, social character, go B+. If you want something more reflective and "teaching," Golden Teacher is the classic choice. Cambodia is the one for energy and shorter, punchier sessions. All three grow kits use the same substrate and method — the only difference is the strain colonising the rye cake.

From Our Counter: What We've Learned Selling B+ Kits

We've been selling grow kits since 1999, and B+ has been a consistent bestseller for most of that time. The two things we hear most often from customers: "the mushrooms are massive" and "I couldn't stop laughing." Both are accurate. The fruits genuinely look dramatic — thick white stems topped with those caramel-gold caps, sometimes bending under their own weight as they push past 25 cm. They're the most photogenic cubensis strain we carry, full stop.

The honest limitation: B+ sits at the lower end of potency for cubensis. If you're experienced and looking for something that hits harder per gram, you'll want to look at strains like McKennaii or Ecuadorian. B+ compensates with volume — those 20–30 cm fruits are heavy, so a single flush gives you plenty of material to work with. According to research by Gotvaldová et al. (2022), psilocybin content can vary significantly even within the same strain depending on growing conditions and harvest timing, so treat all potency estimates as approximate ranges rather than fixed values.

The other thing worth knowing: B+ bruises blue like any psilocybin-containing mushroom when you handle it. That's oxidation of psilocin — totally normal, not a sign of contamination. Handle them gently during harvest and they'll dry cleaner.

Storage and Drying

Fresh B+ mushrooms should be consumed or dried within 48 hours of harvest. For drying, a food dehydrator set to 35–45°C works best — lay the fruits on the trays without overlapping and run it until they're cracker-dry (they should snap, not bend). No dehydrator? A wire rack in front of a fan in a warm, dry room works, though it takes 24–48 hours longer. Once fully dry, store in an airtight jar with a silica gel packet. Properly dried and stored B+ mushrooms keep their potency for 6–12 months.

Safety and Harm Reduction

Psilocybin converts to psilocin in the body — that's the compound that actually interacts with serotonin receptors. Set and setting matter more than strain choice. A comfortable environment, trusted company, and an empty stomach (or at least 2–3 hours since your last meal) make a real difference to the experience.

According to a case report published in BMC Nephrology (2018), acute adverse reactions to Psilocybe cubensis are rare but documented, particularly at high doses or in individuals with pre-existing conditions (PMC6322052). Physical side effects can include nausea (usually in the first 30–60 minutes), dizziness, and elevated heart rate. Psychological discomfort — anxiety, confusion, paranoia — is more likely at higher doses or in uncomfortable settings. If you're on SSRIs, MAOIs, or lithium, psilocybin can interact unpredictably. Speak to a medical professional before combining.

According to research published in Biomolecules (2025), preclinical studies have observed more pronounced effects from whole psilocybin-containing mushroom extracts compared to isolated psilocybin alone, suggesting that other compounds in the mushroom matrix may play a role (PMC11856550). This is an active area of research and one reason why whole-mushroom preparations remain the standard in traditional use.

The golden rule we repeat daily behind the counter: start low, be patient, and don't redose before the 90-minute mark. Most uncomfortable experiences come from impatience, not from the mushrooms themselves.

Frequently Asked Questions

Last updated: April 2026