Do you actually need a pressure cooker?
The most expensive item on any DIY list, and when you can skip it.
The pressure cooker is the single biggest line on a DIY shopping list, usually costing more than everything else combined. So it's worth being precise about when you need one and when you don't.
What it's actually for
Substrate has to be sterile before you introduce your culture, and sterilising means holding 121°C for long enough to kill bacterial endospores. Water at normal pressure tops out at 100°C; a pressure cooker at 15 PSI reaches 121°C. That's the entire reason it exists in this hobby.
When you can skip it
- Grow kits arrive colonised. Nothing to sterilise, nothing to buy.
- All-in-one bags arrive pre-sterilised with an injection port. Same story.
- Monotub with bought spawn: colonised grain spawn plus pasteurised (not sterilised) bulk substrate needs no pressure cooker at all. Pasteurising happens at 60–75°C, which a big pot on the stove does fine.
When you can't
- PF Tek jars have to be sterilised. The guide describes a 2-hour boiling workaround, and it's honest to say it works less often — boiling can't kill endospores, so you're gambling on a low starting count.
- Making your own grain spawn for a monotub. Grain is exactly the kind of nutritious, contamination-prone material that demands real sterilisation.
If you do buy one
Get one that holds 15 PSI and fits your jars standing upright — 12 litres is a sensible floor. It lasts decades and also cans vegetables, so the cost per grow falls fast if you stick with the hobby.
The honest summary: your first grow almost certainly doesn't need one. Buy it when you decide DIY spawn or PF Tek is your path, not before.