There are countless materials and designs for creating trellises for beans and tomatoes, but not all designs are simple. Also, not all materials are sturdy enough for growing certain vegetables. For lighter climbers, including pole beans, you can get away with a few garden stakes and some string. For tomatoes and larger, more aggressive bean plants, you'll need a sturdier structure to support them as they grow. With a few cedar or redwood posts and some twine, you can make a simple yet sturdy trellis to grow your beans and tomatoes.
Place a tape measure on the ground along where you will plant your tomato and bean plants. Extend the tape to 6 feet. Place stakes in the ground at each end of the measuring tape.
Measure 3 feet on the ground at a right angle from one of your stakes and mark that point with a stake. Then, measure at a right angle from that point 6 feet in a straight line and mark it. You should end up with four points, creating a rectangle, which is your outline for the trellis.
Dig down into the soil about 1 foot at each of the four stakes. Pound the first two 10-foot posts into the holes vertically. The two posts should be on one end of your trellis, where they are spaced 3 feet apart. Pound the posts into the holes, angling them toward each other so that they cross at about 1 foot down from the top of the posts.
Tie the top of the posts together where they cross with green twine. Use sturdy knots, wrapping the twine around the posts several times. Backfill dirt into the holes if needed and pack it down firmly. Repeat this process for the vertical posts on the opposite end of the trellis. At this point, the trellis should look like two teepees spaced 6 feet apart.
Tie the 6-foot posts horizontally between the two teepees, spacing them in 2-foot intervals. Secure them with the twine using sturdy knots. You should have four horizontal posts on each side of the trellis.
Place the final 6-foot post between the vertical posts at the very top, above the point where they cross. Secure with twine.