No, EGG, soybeans do not require a trellis. They are bushes about 24" tall. Most varieties are self-supporting; but if planted too closely, in partial shade, or grown in windy areas, they may flop over. Should they need support, I just tie a loop of string around the whole row, held up by a few poles.

Your biggest challenge may be your location, if your summer heat is excessive.

"zeedman"

Thanx for the info.

E G N

Hey, E G N:

You don't need to grow you edamame ON a cage, but you probably will need to grow them IN a cage. At least, that has been my experience. EVERY creature out there that eats plant matter just LOVES to eat soybean plants at any stage. I can't get anything out of them in my yard unless they're completely protected by a critter-proof structure. Others have commented here before about the same experiences.

Just something to consider.

Ditto on Denninmi's comments. Never needed rabbit fencing until I began growing soybeans. If you can't keep the deer & rabbits out, chances are that they will destroy the soybeans completely.