Short answer- yes. If they are allowed to.

If your trellis is in a part of your property that isn't visited by deer, then they might not come close to try. But if you think your garden space would benefit with deer enclosure- then yep, beans should be supervised too.

In my yard, I have a long front yard that is rather human occupied and gardened, so if I strung a trellis (and did once or twice for tomato plant surplus) there the deer wouldn't bother. But if I tried that on the side or back property where the deer wander as they will. Lol, nope.

Though I would too encourage you to try it out next spring where you got plans for it, and see what happens. Try out scares or repellents that are supposed to work on deer, see what works or not. Try out some seed, see what happens.

Deer can smell, so if your beans smell good to the deer they will wander over and check it out even if that's in the middle of the night when no one's around. The farmers have the advantage that they farm in an area where hunting isn't banned. I plant my beans on poles just inside the fence so that there's a second layer of obstruction that they have to navigate to jump into the garden. Any bean plants that extend thru the fence get eaten.

My gardens are both rural & suburban, in locations 6 miles apart. There are deer in both locations, and they love beans, peas, and soybeans. The best case scenario for unprotected beans is that they eat only the leaves, which they will do several times, and severely stunt the plants. Worst case scenario is they eat the emerging sprouts, or eat the plants to the ground.

My suburban garden is fenced with 6' welded wire. Deer are capable of jumping that high (they have done so twice in 20 years) but will do so only if they see a clear landing site. The ground was newly planted & unobstructed when the deer jumped in. Rows of trellised or caged vegetables just inside the fence can discourage them quite effectively.

You might also want to consider an electric fence. It should consist of several lines, spaced closely enough that it is impossible for the deer to step between them, or to easily jump over. My rural garden is fenced that way, with 36" of chicken wire on the bottom (to keep out rabbits) and electric wires up to 6'. I hang flags on the top wire so the deer can see it clearly, and augment that with several windings of baling twine.

It has been my experience that deer learn, and have good memories. An electric fence is most effective if used early in the season, before the deer learn that the garden means "food"... if turned on after damage has started, the deer are likely to just jump in anyway. I found that out the hard way, when I was late turning on the fence one year, and they had already started eating the corn - they broke right through the wire to finish the job. If zapped early (probably more than once) they are unlikely to be a problem for the rest of the season. I usually turn my fence off in July, and have had no problems. But if the deer population is high, it may be necessary to leave the fence on all year.

Thank you all for your responses. They are what I expected. I will keep the legumes inside the fence, put squash outside and hope for the best. The posts I have for the fence are repurposed from a previous deer fence, and are at least 12’ long. So, once in the ground, they should be at least 8 feet tall. I will have trellises and other vertical plant supports inside to deter jumping. If the ground hog makes trouble, I might have to add electricity.

My experience is that they eat the leaves but not the beans, which of course ultimately makes it hard for the plants to ripen and produce new beans.

I will keep the legumes inside the fence, put squash outside and hope for the best.

Deer will eat squash (and cucumber) leaves as well but for some reason they like some and not others. I've never seen a pattern to it.

Deer will take bites out of squash too.

Can anyone tell me how much a 1acre market garden would spend on seeds in a year - roughly i mean. Thanks everyone