Trellises provide a support system for vines to climb so you can keep sprawling vines contained near the pot. Devil's ivy (Epipremnum aureum), which also grows outdoors in U.S. Department of Agriculture plant hardiness zones 10 through 12, is one of the most common vines grown as a houseplant, but you can grow practically any vine indoors. A trellis doesn't need to be fancy or expensive -- you just need a series of vertical and horizontal or diagonal supports. A simple ladder design works well and can be made at almost no cost when you use branch pieces gathered from outside.
Measure the height of the container and add this measurement to the desired height for the trellis. Cut two 1-inch-diameter, straight branches to this measurement. A trellis between 1 to 3 feet tall is usually best for houseplants because the risk of becoming top-heavy and falling over increases as the height increases, but this also depends on the size of the houseplant pot. If you have an 18-inch-tall container and want the trellis to measure 3 feet above the soil line, cut the branches 4 1/2 feet long.
Measure the distance from side to side of the back one-third of the planter. Measure one-third of the distance in from the back of the planter, and measure from one side of the container to the next at this position. Cut 1/2- to 3/4-inch-diameter branches about 6 inches longer than this measurement. Cut one branch piece for every 4 to 6 inches of trellis height, depending on the desired spacing for the trellis rungs.
Lay the two long, 1-inch-diameter branches on a flat work surface. The distance between the branches should be the same as the side-to-side measurement of the container. Measure up from the bottom of each pole and mark the branches to indicate the container height -- measure 18 inches from the bottom of the poles if they pot is 18 inches tall. Make a small mark every 4 to 6 inches above the container height mark, depending on the desired spacing between the horizontal rungs.
Lay the shorter, 1/2-inch to 3/4-inch-diameter branch pieces horizontally across the vertical branch poles at each mark. Tap 1- to 1 1/2-inch ring shank nails through the horizontal pieces and into the vertical branches. Use one nail on each end of the horizontal pieces. Repeat this until you attach all the horizontal branch pieces.
Wrap each joint with natural twine where a horizontal branch intersects the vertical branches, if you wish, to give the trellis the look of natural lashing. Wrap the branches several times in an X-pattern, which also helps stabilize the joints.
Push the trellis into the soil until the vertical branches reach the bottom of the planter. Sharpen the ends of the branches, if needed, to make it easier to push the trellis into place.
Wrap the ends of the climbing vine around the trellis supports until the plant attaches itself to the trellis. Vine support mechanisms vary greatly, with some using adhesive rootlets and twining stems to grip the trellis.