George Ball, chairman and CEO of Burpee, says seeds are probably the perfect mail-order item. They're small, easily shipped and cost-effective for the gardener.

"A $3 packet of seeds can give you $300 worth of store-bought merchandise, in terms of like a beefsteak tomato," he says.

As such, they can be too easy to order. (And remember: Tomatoes and many other plants have to be started indoors, so you also have to plan for the time and space these seeds will require.)

"Seeds aren't real expensive, so you buy too many," said Roger Cook, the landscape contractor for PBS' "Ask This Old House" and "This Old House" and owner of K&R Tree and Landscape in Burlington, Mass.

Cook says. "There should be some social Web site where if I buy a packet of seeds and use only half of them I could trade with you for some other seeds.

"It's way too easy to buy too many, because when you're spending two, three dollars a packet, it doesn't add up that quickly. You buy 20 packets, that's $60, and you figure, 'Well, I can live with that.' Then spring comes and I've got a 6-by-12 garden, and where am I going to put 20 packets of seeds?"

Adds Ball: "When it comes down to the moment of decision, especially for new gardeners, take care and don't over-order. That sounds crazy coming from me. But don't over-order. It'll just disappoint you in your first year. It's like a gym membership. If you kill yourself at the gym that first month, your likelihood of hating the gym is very high."

And don't give all your business to the first catalog that pops in. As Cook says, "It's very easy to fall in love with the first girl at the dance."

People in the catalog business know customers are waiting, so there's not a great deal of time between all the arrivals. Usually if you order fairly quickly you'll be fine, and the items won't be sold out.

"The other thing you can do is supplement the catalogs with your local garden centers," Cook says. "They always carry a big, big selection of seed. So if you lost something and didn't get what you wanted, I'd check with the garden center to see if they have what you wanted."