Pumpkins are known for their large size and distinctive, bright colors ranging from deep orange to white. While the pumpkin plant has a low-lying growth habit that doesn't require vertical training, the plants benefit from a little support to increase air circulation and keep the fruits from resting directly on the soil. To build a trellis for pumpkins, make a squat pyramid that rests over the hill your pumpkin is planted in and allow your plant to grow out over top of the frame.
Lay two of 4-foot poles horizontally on the ground spaced just under 4 feet apart. Set your other two 4-foot poles vertically over the horizontal poles 3 1/2 feet apart to form a square. Nail straight through each intersection to secure the square frame of poles together.
Place two 3-foot poles horizontally over the last placed vertical boards. Center and adjust the 3-foot poles 3 feet apart. Nail the poles together at the intersection.
Set the other two 3-foot poles vertically over the 3-foot horizontal poles and adjust them to 2 1/2 feet apart. Nail these poles to the rest of the structure. By now you should start to see the pyramid-like nature of the structure taking shape.
Create the final tiers by laying down two of the 2-foot poles horizontally, 2 feet apart. Center them, and nail to secure. Place the last of the 2-foot poles vertically, 1 1/2 feet apart, center them and secure with nails.
Place your pumpkin trellis over the mound where you are going to grow your pumpkin plants and center it so the top opening is over the uppermost portion of the hill. Train the plant as it grows to flow over the trellis and arrange the vines as needed so your growing pumpkins sit on top of the poles to keep them off the soil.