I never really thought about it to be honest.
I'd be more worried about bacterial infestation rather than chemical break down. I would expect a dry fertilizer to last a few years at least, if stored properly.
Same with soil, it would take a while to get wet again though. If it appears 'iffy', I just use it outdoors. But i usually go through it pretty quickly.
Things like rooting hormone, I'd probably buy new if I were doing an 'important' project (my current batch is a few years old). As it is, I only ever use it because I have it. - I never was convinced it made much of a difference anyways.

SW,

The soil should be fine. Peat does not break down unless it is exposed to the elements.

Fertilizers, being a chemical mix, may be a different story. Why don't you ask John when you place your order?

As for rooting hormone-most people have better experience not using it from what I have heard and read. I never noticed much difference so I stopped using it.

Linda

I guess soil will be fine for couple for years, unless it was wet and you got some stuff growing in it.
Fertilizers are mostly salts, and with 20 years of lab work I'm sure that you can store them for a very long time if kept dry and away from heat and sun. Some dry mixes are getting solidified, but usually you can take chunk off or just smack it (if bagged) with a hammer to crush solid pieces.
Were you able to get current catalog from Cape Cod Violetry? I requested one by e-mail with no luck.

Aggie

I got a catalog by email, using the ccviolets@msn.com address. If you used the other address I've seen floating around, you might want to try this one. Or I can forward the PDF if you'd like. Although it might be good to make contact with them to make sure they're getting your messages

I think I'll go ahead an get a larger bag of the mixes and not worry about it going bad. I figured the vermiculite and perlite would be fine, but the peat seems more iffy.

I'll ask about the fertilizer, too. There's no date on the bottles of liquid that I have, so it doesn't seem to be a top-of-mind concern for the companies.

SW,

Peat moss, also known as Canadian Peat or the 'brown kind' is partially decomposed peat. It will not deteriorate further unless it is exposed to the elements, mainly moisture. Michigan Peat, aka the black kind, is the same product except that it has decomposed further than the Canadian. You do not want to use this for any gardening or indoor growing as it has rotted to the point of being useless. That is why it is cheaper than the other.

Linda...and I'm starting to realize how much of a plant nerd I truly am. Lectures on peat moss...sheesh.

I think the rest of us are just as nerdy as you, being students who will eagerly listen to lectures on peat moss. :)