Grow kits
The McKennaii Ready-2-Grow Bag is a sealed all-in-one Psilocybe cubensis grow kit that ships with live McKennaii mycelium and substrate combined in a single bag — no assembly, no substrate prep, no sterile technique. Keep it at 23-25°C and harvest 200-500 g of dense, potent McKennaii mushrooms in 2-3 weeks. McKennaii sits alongside APE and Penis Envy as one of the three strongest cubensis strains in commercial cultivation, with an estimated 0.6-0.8% psilocybin by dry weight — roughly 50% more per gram than Golden Teacher.
McKennaii is the strain people graduate to after Golden Teacher. Named after ethnobotanist Terence McKenna, it consistently tests in the upper bracket of cubensis potency. Analytical studies on cubensis alkaloid content — including Tsujikawa et al. (2003) in Forensic Science International and Gotvaldová et al. (2021) in the Journal of Chromatography A — show that psilocybin concentrations across cubensis strains range from 0.14% to over 1.0% dry weight. McKennaii lands at an estimated 0.6-0.8%, compared to 0.4-0.6% for Golden Teacher and B+.
What that means in practice: someone who's comfortable with 2.5 g dried Golden Teacher will find the same weight of McKennaii a significantly more intense experience. Same active compound, same receptor binding — but the concentration difference changes the character entirely. The visuals are heavier, the introspective depth is more pronounced, and the body load is noticeably stronger. According to a 2021 study published in the Journal of Chromatography A (Gotvaldová et al.), individual cubensis strains show consistent alkaloid profiles across multiple grows, so this isn't batch-to-batch luck — McKennaii reliably delivers at the top end.
According to research published in Frontiers in Pharmacology (PMC11856550), preclinical studies have shown more pronounced effects from psilocybin-containing mushroom extracts than from isolated psilocybin alone, supporting the idea that the full alkaloid profile of a strain like McKennaii contributes to its distinctive character.
The numbers tell the story better than any marketing copy. Here's where McKennaii sits relative to the strains we carry:
| Strain | Estimated Psilocybin (% dry weight) | Relative Strength vs Golden Teacher | Character |
|---|---|---|---|
| B+ | 0.4-0.5% | Slightly below baseline | Gentle, forgiving, good first strain |
| Golden Teacher | 0.4-0.6% | Baseline | Warm, insightful, balanced |
| McKennaii | 0.6-0.8% | ~50% stronger | Intense visuals, deep introspection, strong body load |
| Penis Envy | 0.7-1.0%+ | ~75-100% stronger | Heavy, slow onset, overwhelming at standard doses |
McKennaii hits a sweet spot: substantially stronger than the entry-level strains, but not quite as unpredictable as Penis Envy. We'd call it the best cubensis strain for someone who's done 3-4 grows with Golden Teacher and wants to step up without jumping straight into the deep end.
The McKennaii Ready-2-Grow Bag arrives as a single sealed unit. Inside the bag: fully colonised McKennaii mycelium integrated into its growing medium. No separate substrate bags, no syringes, no casing layers to apply. The mycelium is already established and ready to fruit.
| Specification | Detail |
|---|---|
| Species | Psilocybe cubensis |
| Strain | McKennaii |
| Format | Sealed all-in-one grow bag (mycelium + substrate) |
| Estimated psilocybin content | 0.6-0.8% dry weight |
| Fresh harvest yield | 200-500 g (single flush) |
| Time to harvest | 2-3 weeks |
| Optimal temperature | 23-25°C |
| Number of flushes | 1 |
| Sterile technique required | No |
| SKU | SH0257 |
We've been selling grow kits since 1999, and McKennaii is one of the strains that generates the most repeat purchases — and the most "I wasn't ready for that" conversations. The mushrooms themselves tend to be smaller and more densely packed than Golden Teacher fruits. They're not the prettiest things in the terrarium — stubby, dark-capped, sometimes a bit gnarly looking — but what they lack in stature they make up for in sheer numbers and concentration.
The honest limitation: McKennaii is not a beginner strain. If you haven't grown before, start with a Golden Teacher or B+ kit to get your process dialled in. The growing itself isn't harder — same bag, same temperature, same timeline — but the potency means any dosing mistake hits harder. We've seen people assume "a cube is a cube" and weigh out their usual Golden Teacher amount. That's how you end up with a much more intense afternoon than you planned for.
One thing worth mentioning about the physical product: when you open the outer packaging, you'll notice the bag feels warm and slightly firm — that's healthy mycelium doing its thing. If it smells earthy and mushroomy, you're in good shape. If it smells sour or looks green, that's contamination — contact us and we'll sort it out. In over two decades of selling these, contamination rates on sealed bags are extremely low, but it does happen occasionally.
Don't use aluminium foil around the bag — it's not needed with this kit format and can trap moisture unevenly. And don't open the bag to "check on things" before harvest time. Every time you break the seal, you introduce potential contaminants. Patience is your best tool here.
McKennaii's 0.6-0.8% psilocybin content means you need substantially less dried material to reach the same intensity as a standard-potency strain. According to Medical News Today, psilocybin is converted to psilocin in the body, which then binds to serotonin 2A receptors — the dose-response relationship is fairly linear up to moderate amounts, then steepens. With McKennaii's higher concentration, that steepening arrives sooner than people expect.
A 200-500 g fresh harvest dries to approximately 20-50 g. At a conservative estimate of 0.6% psilocybin per gram dried, that's 120-300 mg of psilocybin total — enough for 13-33 sessions at a moderate 1.5 g dried dose. Clinical research on psilocybin typically uses 10-30 mg of pure psilocybin, which corresponds to roughly 1.5-4 g of dried McKennaii depending on exact potency.
If you're experienced with Golden Teacher at a particular weight, reduce your McKennaii dose by at least a third for your first session. Same compound, higher concentration — respect the difference.
McKennaii's potency makes set and setting more important, not less. A comfortable, familiar environment with someone you trust nearby is the baseline. Empty stomach, nothing planned for the next 6-8 hours, phone on silent. According to research reviewed by the Trimbos Institute, the majority of negative experiences with psilocybin mushrooms are associated with high doses in uncontrolled settings — not with the substance itself.
Watch out for interactions with serotonergic medications, particularly SSRIs and MAOIs. Psilocybin acts on the same serotonin receptors, and combining it with medications that affect serotonin levels can produce unpredictable results. If you're on any medication that affects serotonin, do your homework before proceeding.
According to a study on Psilocybe cubensis safety profiles (PMC7749179), researchers examined the effects of cubensis extracts on cell growth rates, finding no cytotoxic effects at standard concentrations — but this is in vitro research, not a green light for reckless dosing. Start low, be patient, and don't redose before the 90-minute mark. We hear "it's not working" at least twice a week in the shop. The answer is almost always: wait.
Complete your setup with a heat mat and thermostat to hold that 23-25°C sweet spot — temperature swings are the number one reason for slow or stalled grows. If you're planning to dry your harvest, a food dehydrator gets you shelf-stable material in 8-12 hours. And if McKennaii sounds like too much for a first grow, the Golden Teacher Ready-2-Grow Bag is the same format at a friendlier potency level.
McKennaii contains an estimated 0.6-0.8% psilocybin by dry weight, versus 0.4-0.6% for Golden Teacher. That's roughly 50% more per gram. If your comfortable Golden Teacher dose is 2.5 g dried, start McKennaii at 1.5-1.7 g and adjust from there.
A single flush typically produces 200-500 g of fresh mushrooms. Fresh material is about 90% water, so that dries down to approximately 20-50 g. Yield depends on temperature consistency — kits kept at a steady 23-25°C tend to land at the higher end.
No equipment is strictly required — the bag is self-contained. That said, a heat mat with thermostat makes a real difference. Maintaining 23-25°C with ambient room temperature alone is tricky in most European homes, especially outside summer.
Expect 2-3 weeks total. Pinning usually starts within 7-14 days, and mushrooms reach harvest size 5-7 days after that. Don't open the bag early to check — you'll introduce contaminants and potentially delay the process.
This kit is designed for one flush. The sealed bag format prioritises simplicity and contamination resistance over multiple harvests. If you want 2-4 flushes, look at the traditional tub-style grow kits with a perlite layer — they're more hands-on but produce over a longer period.
The growing process is identical to any other Ready-2-Grow Bag — same temperature, same timeline, same zero-assembly setup. The strain itself is strong, though. If you've never dosed psilocybin mushrooms before, we'd point you toward Golden Teacher first so you can calibrate your sensitivity at a lower potency.
Store the unopened kit in the fridge at 2-8°C. It stays viable for several weeks refrigerated. Once you take it out and bring it to room temperature, the mycelium activates and you're on the clock — so only start when you're ready to commit to the 2-3 week grow window.
Fresh McKennaii has a strong earthy, slightly nutty aroma — more pungent than Golden Teacher. Dried, the taste is intensely mushroomy with a bitter edge. Most people find it easier to consume as a tea or blended into food rather than eaten straight.
Last updated: April 2026
Medical disclaimer. This content is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before use of any substance.
