A native of Brazil, the mandevilla (Mandevilla spp.) produces verdant green foliage as a backdrop for its 4-inch-wide, pink, trumpet-shaped blooms. Thriving in U.S. Department of Agriculture plant hardiness zones 9 through 11, the stems of this woody vine grow in a twining fashion, meaning they spread by wrapping and twisting themselves around support structures. Individual stems reach heights of up to 10 feet, and require direction and pruning beginning at planting time to produce even, upward growth.
Put on gloves to prevent direct contact with the mandevilla vine's irritating sap. Cut back all but the mandevilla's three to five strongest, vigorous stems using pruning shears. Make each cut 1/4 inch above a lateral stem, leaf or leaf bud.
Cut the terminal end from each of the remaining stems. Make each cut 1/4 inch above the second set of leaves to encourage side branching.
Grasp one of the stems, and place it against the bottom of the arbor or trellis. Wind the stem through the bottom openings of the support structure in a sideways manner to spread it outward. Tie the stem to the support structure every 6 inches with a piece of string or a plant tie. Tie the string tight enough to hold the stem in place but loose enough to allow natural movement and space for the stem's circumference to increase. Repeat this process with the mandevilla's remaining vines, spreading them out evenly over the base of the support structure.
Unwind the vine's new growth from the support structure once it reaches 4 to 6 inches long. Re-wind the new portions of stems in a back and forth, horizontal direction to evenly fill the structure. Tie the new portion of vine to the trellis or arbor in the same manner as before. Check the previous ties, and remove any that have lost 75 percent or more of their slack.
Continue to unwind and re-position the new growth in the same manner as before. Remove old ties before they become tight or constrict the mandevilla's stems.
Wind the tips of loose stems back down into the support structure once they reach its top. Repeat this process as the vines lengthen to train the vine to grow downward along the trellis or arbor.