SWIM has heard that using too fine of vermiculite will not allow the mycelium to form inside the jar- because it is too condensed, not leaving enough room for it to grow.
Is that true?

Swim thinks the only difference is moisture retention. Fine holds slightly more water then coarse. Just dont pack it tight and it will grow.
Swiy should look into using grains instead. Its way easier and better yeilds.

I concur. Very fine vermiculite is really easy to saturate and end up with too wet of a substrate. The coarser stuff is much easier to control moisture content.
Also - grain takes a little more care when working with it, but yeah, as weisswolf's SWIH stated, the yield is much better. Sometimes the simplicity of jaring up a few PF style cakes using vermiculite is a nice trade off however, if yield isn't of primary concern.

Good luck!
-idt

The reason that vermiculite is hard to find these days is because 70% of the vermiculite available in North America came from Libby Montana which had asbestos occurring naturally in the same ore. Personally I used vermiculite a lot and it worked great but there are alternatives that have a much less chance of causing cancer down the road. Perlite so far has never been found with asbestos ,most likely because it is a volcanic glass and asbestos is a naturally occurring mineral and the two are rarely if ever found in the same deposits.

SWIM has grown brf when he started out. Probably acouple dozen times. Have always used fine verm, and only coarse acouple times. If you follow the directions exact for the verm/flour/water ratio you will have just enough moisture and not a wet sloppy substrate. Fine verm will colonize just as fast as coarse verm. Have never had any contams and colonization has always completed at the latest the 3 week mark.

thanks for the replies everyone- very helpful!

yeah you really need to stop using the old school BRF jar method. You just have to make the investment for a pressure cooker. After that I can produce a half pound dried mushrooms for about 50 bucks and that is only because I buy my hpoo instead of pasturize myself. I am so happy I have a local poo vendor now.

Your post is really confusing. The jar method SWIM uses involves a pressure cooker.

What is hpoo?

My guess is (h)orse manure (poo)

yeah he means horse manure. it one of the best manures for mushrooms. But earthworm castings work just as well and its cheaper (unless you got a 4 wheel drive vehicle and can drive onto farms and get it for free.)
And yes you do pressure cook your jars no matter what you use. he may have just had a slip of the toungue.

you should buy some of paul stamets books. between him and myctopia you dont need much else.

or just find the torrents

yeah if your busted but some people I like to support. and Paul is def one of them.

When I used to do BRF jars I would just boil them had no problems with contamination. I did not buy a pressure cooker until I started using grain for spawn. Once my grain is fully colonized I mix 4 of those in with about 10lbs of horse manure. Put that mixture in a 78qt tub with holes in the sides stuffed with polyfil. Let that colonize 5-10 days and you're ready to fruit. 2 weeks later you'll be looking at 3-8 ounces of dried mushrooms depending on your pinset. It is best to used an isolated strain grown on agar for your jars, but I do not have that available atm. So I just use multispore which usually provides in the lower range 3-6 ounces.

A quick search of the terms monotub or double tub on any of the mushroom cultivation forums will give you what you need to know.

Sorry that my first post up there was sort of confusing.