Just Bento

Your lucky you can get the frozen kind, I can't even get that (and it's not like it's a single cuisine ingredient either, I need to find some better food shops). I'm afraid I can't give you any gardening advice (I have the touch of death when it comes too plants), but I've found that you can subsitute other beans of similar size in many recipies although not where the edmame is the key flavour.

Edamame can be grown like bush beans (haricot beans). Plant them in April-May, and they should crop in late July-August. You need to plant a lot of plants to have enough edamame, so try to stagger your harvest so you have a constant supply.

The trouble I had when trying to grow edamame was that the ends of the plants got attacked by these shiny black bugs, which killed them off. You may have better luck though...If you live in Modena, the weather should be warm enough for sure.

I believe that it is also good to give them something to climb on, or at least that's what the variety I have at home specified.

Also I have had a terrible time with snails eating my snap peas this spring, so you may want to leave enough room to put in some beer traps since I have a feeling that they will probably go after the soybeans too (damn those non-native pests).

This article is from the wrong part of the world for this thread, but after reading it I decided to give edamame a try this summer:
http://www.texasgardener.com/pastissues/mayjun05/Soybean.html
Summers in my part of Texas are usually around 98F/37C and dry, so I'm always surprised to read that anything does well here in full exposure to the sun. It sounds like bugs are the biggest problem as long as the plants have enough water. I'll be planting soon (hopefully) so I'll keep you updated if I find anything useful.

I just picked all of my edamame and wanted to share my success!

I got about twice as many pods as shown in this picture. I was surprised that they did so well--I've never had a garden before, so I ended up planting too late, only fertilized once, and rarely watered, but they grew like crazy. I had about a dozen plants worked into a meter of blank space against the side of my house. I didn't have many problems with bugs, but I did mist with organic neem oil once. The leaves got chewed up, but they plants grew far faster than the damage could set in, so it didn't bother them. Full sun, temperatures averaging 95F/35C.