Vermiculite is very pricey to put in the ground - do you really need it? Union county clay is greatly improved by compost alone - I used to garden there. call up your town hall and ask if there is a town or county compost program. If not, try the local garden centers.

I second the advice above. All you need is compost. Just mix a 2-3" layer into the top 8-12" of soil. You do not need vermiculite in the ground.

I too have been looking for vermiculite.... ZeeWire, by any chance are you trying to make Mel's Mix? (Square Foot Gardening) I am, and Bartell's Farm Supply on Central Ave, Clark told me there's "a problem with the process" and it's hard to get, whatever that means. I resorted to using a mixture of compost and peat moss only. We'll see how that works. If you have any luck, I'd still like to know where to find it and how much it cost you.
Lynne

Try adding about 20% perlite instead. That helps with the drainage. Don't layer it, but mix it thoroughly into the soil mix.

Thanks for the replies everyone.

Lynne: Yes, my intention was to create Mel's Mix for the SFG, mine is 12in high and 4x12, so I needed 1/3 of Vermiculite (around 16CF) but after I found it in a couple places I realized is was way too expensive to use, as the bags were quite small (not even 0.5cf) and I would need "too many".

So my approach was to create it using 1/3 Peat Moss 1/3 Composted Cow Manure/Humus & 1/3 Top Soil instead. Let's hope it works.

Check out www.vermiculite.com

Interesting stuff. Didn't know it was that hard to find.

I stumbled upon this thread. I live outside Philly and have also been searching for vermiculite. I'm not familiar with new jersey but according to google maps one of the sources I found is about 25 min away from union county:

wh milikowski inc.
42 Colonial Dr
Piscataway, NJ,
Phone: 732-465-9000
$13.15 4 cu ft bags coarse vermiculite

For any other nj searchers there is another company, griffin greenhouse, with locations in ewing and bridgeton. $22.18 for 6 cu ft

In North Jersey, you can get good-sized bags at Condurso's in Montville. They're still not really cheap, but a much better deal than trying to buy a lot of little bags.

Parker Gardens on Terrill Road, Scotch Plains carries it.

Here is a link that might be useful: Parker Gardens web site

I just started a square foot garden and I had a very difficult time finding large quantities of Vermiculite at a reasonable price. I went to about 20 gardening centers and then started calling others to no avail.

I then went to the web and found references to:

WH Milikowski inc.
42 Colonial Dr
Piscataway, NJ,
Phone: 732-465-9000
$13.15 4 cu ft bags coarse vermiculite
(Thanks to original comment above)

They do not have a website.
This price is very cheap compared to the other options.

They have it and they have to peat moss. The lady there told me that they are a "greenhouse supply center" and that they are only supposed to sell to greenhouses. She asked me if I am making "Mel's mix". They have a lot of people going there who heard of them from the web forums.

The Vermiculite was Excellent, coarse ground and was labeled
Whittemore Company Inc...
www.Whittemoreco.com
(978)681-8833

If you are not near Piscataway, I would recommend contacting them and asking them which DISTRIBUTORS in your area carry their products.

Bottom line is that you will not likely find the large (cheap) bags at your local gardening center. The only people who buy the large (4,6 or 8 cu ft) bags are greenhouses and people doing square foot gardening. To buy it or find out who sells it, you may need to pretend top be a greenhouse worker. When you buy it they may ask you for a Tax ID number. Of course you can tell them that you don't have it with you, pretend to make a cell call to get it with no answer.

In New Jersey, Ferris Farms Agway in East Brunswick, NJ carries coarse vermiculite in 4 cubic foot bags for $19.99 as of 1/30/2011.

I second NJGardenGuy, Agway in Englishtown carries large bags of both vermiculite and Perlite.