Have you ever used a tree branch as a trellis for string beans?
No, but that's a great idea!  I should try it.
How large is your vegetable garden? 
It is about 40x50 feet.
That is bigger then my back yard. How do you become a 4H member?
When I was in the fourth grade, fliers were sent out to the local families. I joined and have always been involved in some way.
Is 4H just for volunteers or is there a membership?
There is a membership.
What other vegetables do you grow in your garden?
When I was in 4H, I learned to grow pumpkins, eggplants, sweet potatoes, green beans and radishes.
But do you still grow those in your garden now? Have you expanded to more exoctic vegetables like a watermelon radish?