Vermiculite

Does the vermiculite need to be horticultural grade because i've seen some at a much reduced price but it is advertised for building.

I don't think there is any difference except price.  Vermiculite is a mineral product.  By saying that it is horticultural grade, the seller gets to add a price premium.

I might be wrong.  I sold vermiculite about 55 years ago to the building trade.  It looked exactly like the stuff I bought for my MM.

I hope someone with more knowledge than I will chime in.

I get mine in the insulation department at Menard's. It is the same stuff.

GG

For more info check the vermiculite sub forum.

It depends on the manufacturer. Some vermiculite's and perlite's also are treated with dust inhibitors and water repellent additives for the building industry. I am not familiar with European manufacturers. I would suggest you contact them directly.

sarahmitzie wrote:Does the vermiculite need to be horticultural grade because i've seen some at a much reduced price but it is advertised for building.

Hello Sarah ,
Welcome to WSF .
 I've  lived  at the west end of the M4 motorway in South Wales  for the last 8 years ... played in the construction & telecoms industry a while prior to that .
I converted over to the All new square foot gardening & Mel's mix about four years ago from his original mother earth idea.
 
My ANSFG beds are fantastic producers .. some of the photo's are in the gallery in  " BIG STUFF "

Construction grade coarse or medium vermiculite insulation granules is fine for making Mel's mix .


Last year I got mine from Keyline builders merchants ...one in most large cities/ towns  ( former T&P , Travis Perkins and several other buy outs of late ) for £22 + VAT for 100 litre bags with free delivery for the ten I purchased .



If your making small pencil holes in peat to sow plug type seedlings ( It works very well as it helps keep the moisture level around the seeds fairly constant .) pop some 2 to 3 mm graded horticultural vermiculite ( £7 ish for 2 kg ??? ) in the bottom of the 2/3 of the hole pop in the seed and sprinkle a covering layer of the small stuff over then gently water .

Tip.

 I have purchased one of the cheapie £1.50 3/4 litre green plant plastic watering cans out of Aldi .
 Slipped a 400 mm x 10 mm bore  length of high quality soft silicone rubber tube  over the spout , on the other end of th tube I have unscrewed a dead biro pen and inserted the threaded end of the barrel in the tube. 
I can now accurately water from above in a very tiny low pressure stream all over a block of four seed trays ( 93 mini seed tubes )  without disturbing seeds, vermiculite or the seed labels .