What a coincidence: I was watching Martha Stewart's new gardening DVD on Saturday, and a guest in her show (the owner of Heronswood nursery in the Pacific NW) mentioned that vermiculite gets compacted and heavy over time, so it is not recommended in a seed mix for seeds that take a long time to sprout. He recommended perlite instead.

Usually the recipe for seed starting mixes includes both but since the scare with asbestos in vermiculite, I see it omitted. Here is a link that explains the difference between the two on the NY American Rhod. Society.

Verbena is commonly sold by the flat at many nurseries. You won't have a problem finding them. I've never prepared the soil special for them. Just the same as any other annual.

Isn't Barlow's in Sea Girt near you? I've never been there but my SIL who lives near there is always talking about it.

Here is a link that might be useful: Perlite vs. Vermiculite