The fragrant, flowering sweet pea (Lathyrus ororatus) and the tall form garden vegetable pea (Pisum sativum) are both climbing vine plants. Whether you prefer to grow the flower to enjoy the colorful blossoms that work well for cut bouquets or you grow the tasty vegetable, both plants benefit from a frame to support the vines. Frames encourage the vines to grow upward, taking advantage of vertical garden space and keeping the plants off the ground where they are susceptible to rot. A simple obelisk frame made from tree branches provides this vertical support and serves as garden artwork.
Tie four 1 1/2-inch diameter branch poles together with heavy-gauge wire, such as 16-gauge, approximately 12 inches from the ends of the poles. Use 8-foot poles to make a frame that is approximately 6 feet tall or adjust the lengths accordingly to build a frame to the desired height. Wrap the wire tightly so the poles stay together at the top when you adjust the bottom.
Spread the opposite ends of the poles apart to form four legs, approximately 18 inches apart. Arrange the legs in a square so there is equal spacing between each leg.
Measure the distance between each pole about 12 inches from the bottom of the legs, and cut four 1-inch diameter branches to length.
Nail the short branch pieces to the legs to create horizontal crosspieces that hold the legs apart. Use 1 1/2- to 2-inch ring shank nails, inserting two nails in at angles for each joint. It helps to set the legs up on a level work surface as you nail the crosspieces in place.
Attach additional crosspieces in the same manner every 12 inches along the height of the frame. Alternatively, you can bend a flexible branch, such as willow, into a spiral from the bottom crosspiece to the top of the structure and nail it in place where it meets the joints. Use two to three spiral pieces in opposite directions if you choose this method to allow a sufficient number of branches for the sweet pea vines to climb.
Wrap each joint with twine or grapevine to conceal the nails and the wire at the top of the poles so it appears as though the structure is tied together, giving the frame a more rustic look while maintaining stability.
Push the frame into the soil over top of the sweet pea plant. If the plant already has a few feet of vine length, weave the vine in and out of the vertical and horizontal pieces of the frame.