What does the well-dressed gardener wear? I have no idea -- but, I can tell you what I like to wear.
For cold weather, I wear light cords with and elastic waist, a turtle-neck and I usually add a fleece pullover. I almost never wear a coat. The pullover is very warm and fits a little better than a jacket. It also has the added benefit of more pockets that zip so things I store in them don't fall out when I bend and twist. Lose-fitting jeans are nice, too but be sure not wear clothes that restrict your movements.
I almost always wear sunglasses and if it is really sunny and not too windy, I wear my straw hat. Sometimes, even in cooler weather I can get a bit sweaty and I have to take off my sunglasses and I then appreciate the shade the hat provides. If it is very chilly, I wear a knitted cap and sometimes a knitted scarf around my neck.
My shoes are some old crocs and I wear socks with them. I think they are the perfect outdoor work shoe. They never give me blisters and I think they give me a good foundation because they are so wide. I really love them -- rain or shine -- summer or winter.
And in warm weather my favorite thing -- short-alls. They are the perfect thing because they are cool and they have plenty of pockets. I usually dress in layers -- but thinner ones. I wear a sleeveless t-shirt and usually a blue jean shirt. I like the sleeveless shirt because it helps me maintain my tan. I always wear my crocs and like to wear short socks with them.
Last year I had an uneven tan on my feet because of the holes in my shoes. I probably will have the same problem this year, but I really don't mind.
I like to wear my straw hat in the summer to protect my face. This hat has a chin strap that holds the hat on in windy weather. Of course, I always wear my sun glasses.
It is very important to wear gloves when gardening. When working with dirt, manure and chemicals your skin can become damaged and this makes gloves very important. I am trying out a new pair of gloves with rubber fingers and palms but I can't recommend them, yet.
In the summer, one of the "must wear" items is bug repellent. I know it is not clothing, but you should wear it each time you go into the garden. It can be miserable without it, especially after dusk.
There really are very stylish things to wear while gardening and plenty of websites that will sell you gardening clothes. I am sorry I didn't show you anything stylish but maybe I gave you some ideas. I think I would have a problem with getting something dirty that is very pretty and gardening is a dirty job.