In a ready-to-use grow kit, Golden Teacher is sold as a forgiving culture. Dutch-Smart's product pages give a first harvest after about three to four weeks at 20 to 25 °C and two to three flushes per kit. Those figures come from the shop, nobody has checked them independently, and they differ between the shop's own pages. In the Netherlands the kit is legal to buy, but the mushrooms are illegal as soon as they appear, so read lesson 6 before anything else here.
3.1What a grow kit is
A grow kit is a box of substrate, usually grain with perlite or vermiculite, that has already been fully colonised by mycelium in a laboratory. The buyer only has to start the fruiting stage. The shop's description of its medium Golden Teacher kit puts it like this: the mycelium "has colonized a substrate of rye and perlite", the top layer is covered with vermiculite, and the box comes with a grow bag with an air filter and a manual in English and Dutch. The step by step instructions are in that manual; this lesson stays with the cultivar.
3.2What the shop pages promise
| Kit | Volume | Time to first harvest | Yield (shop figure) | Flushes | Temperature |
|---|---|---|---|---|---|
| Golden Teacher, medium | 1200 cc | not stated | 400 to 600 g | "multiple harvests" | 20 to 25 °C |
| Golden Teacher, Royale Flush | 1200 cc | 3 to 4 weeks | 400 to 800 g | 2 to 3 on average | not stated |
| Golden Teacher XXL | 2100 cc | not stated | not stated | not stated | not stated |
Two kits of the same volume and the same cultivar come with yield figures that differ by 200 grams at the top end. The kits come from different producers, and yield depends on the substrate, the conditions and the grower. A yield on a product page is an estimate. The yields are for fresh mushrooms, which are mostly water.
The pages also describe the cultivar. The Royale Flush page calls Golden Teacher "reliable" and "easy to grow" with "stable genetics". The XXL page says it produces the largest mushrooms in the shop's range. Neither page links to a test.
3.3Where the easy reputation comes from
The idea that Golden Teacher is a good first cultivar is old and widespread. The 2025 review by Kurzbaum and colleagues records it: Golden Teacher is "renowned for its vigorous growth" and preferred by both beginners and experienced growers (Kurzbaum et al., 2025). The same authors note that such descriptions rest mainly on community reports.
We found no published experiment that compares colonisation speed, time to harvest or yield between named cubensis cultivars. The 2026 study that grew 14 strains under identical conditions reported their chemistry, which is the subject of lesson 4. So the reputation may well be earned, but its evidence is the experience of many growers; nobody has put it to a controlled test.
3.4Flush by flush
A kit fruits in waves called flushes, with a pause between them. The amount and the content of the mushrooms can change from one flush to the next. In a controlled study of P. cubensis, psilocin was usually absent in the first flush and reached its highest level by the fourth, while psilocybin varied by up to a factor of four between flushes without a clear trend (Bigwood and Beug, 1982). That study did not name a cultivar, and there is no reason to assume Golden Teacher behaves differently.
The practical meaning: mushrooms from the second flush of a kit are not a reliable copy of the first, even though they come from the same box.
3.5What the kit cannot tell you
A kit label tells you the cultivar the supplier says it used, the volume and a shop estimate of the yield. It does not tell you how much psilocybin the harvest will contain, how the culture compares with another supplier's Golden Teacher, or whether a given flush will be stronger or weaker. Those questions do not have answers on any product page.
3.6The law comes first
In the Netherlands, the Trimbos Institute states that kits for growing psychedelic mushrooms can be bought legally, because you are not buying mushrooms, and that the mushrooms become illegal as soon as they appear above the surface (Trimbos, drugsinfo.nl). In the United Kingdom, Germany and the United States the mushrooms are illegal too, and a kit that produces them is a problem in itself. A Dutch shop can ship a kit, but the law of the country where it is delivered applies. Lesson 6 has the details per country.
The three kits in the table above, as Dutch-Smart lists them:
Golden Teacher - 1200cc Mushroom Grow Kit
Golden Teacher Grow Kit – Royale Flush
Golden Teacher XXL - 2100cc Mushroom Grow Kit
?Review questions
Answer for yourself first, then open the answer.
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Where do the harvest times and yields on a Golden Teacher product page come from?
Answer From the shop or the kit producer. They are estimates, and two 1200 cc kits of the same cultivar list different yields.
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What evidence is there that Golden Teacher grows vigorously?
Answer Community reports, recorded as a reputation in a 2025 review. We found no controlled comparison of growth between cultivars.
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Is the second flush of a kit as strong as the first?
Answer Not necessarily. In a controlled study, psilocybin varied up to fourfold between flushes, and psilocin rose over the first four flushes.
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Is it legal to let a Golden Teacher kit fruit in the Netherlands?
Answer No. The kit is legal to buy, but according to the Trimbos Institute the mushrooms are illegal once they appear.