Gardeners can choose a mulch that complements the tropical garden theme. Chopped cocoa bean hulls not only keep their rich dark brown color throughout the growing season, they also impart a pleasing chocolaty aroma for several weeks after spreading. Wood chips that are dyed black are also a wise choice for tropical gardens: the dark color absorbs sunlight, adding a few degrees of warmth to help tropical plants thrive in cool areas. The red flowers of dahlia ‘Bishop of Llandaff’ on the left will bloom from July to October, and stand in bold contrast to the dark foliage. Cannas and flowering castor bean intermingle on the right side of the photo, adding further texture and rich amethyst jewel tones that look stunning whether plants are in or out of bloom. Airy stems of South American native Verbena bonariensis keep the whole design from looking too dense, and will self-seed for future seasons of purple blooms. The quickest way to get cannas going in early summer is to buy potted plants. However it’s expensive to replace cannas each year, and the rhizomes are easy to save. After frost kills the top growth, cut the dead foliage down and dig the clump out. Rinse soil from the clump, and allow one week to dry. Store in a dark, cool place. An unheated garage works well. Plant after last frost, and look for blooms about ten weeks after that. Bright, filtered light is better for most orchids than full, direct sunlight. The dappled shade under a tree canopy is ideal. A sheltered area will protect flowers from wind damage. Be sure to bring orchids indoors or into a greenhouse when temperatures dip below 50 degrees F. Even a heated garage will do in a pinch if you experience a cold snap. Vanda and dendrobium orchids tend to be the most cold-sensitive, while cymbidium and cattleya orchids are hardier, so know your orchid to prevent chill damage symptoms like discolored leaves. Gardeners in tropical landscapes or with greenhouse access can choose one of the showy tender varieties of passion flower, like the striking red ‘Lady Margaret’ cultivar. Give these vines sturdy support that will allow the tendrils to grasp, and bring indoors in areas colder than zone 8. Give your passion flower vines at least a half day of sun, and keep moist. An early spring pruning will remove old growth and open up the plant for easier blossom viewing. Butterflies will want to visit your passion flower plants, especially the Gulf fritillary, which will lay eggs only on these supporting host plants. If you can put up with a few chewed leaves, you’ll allow the next generation of butterflies to mature. Here, an angel’s trumpet (brugmansia) with a strong central trunk grows happily in a galvinized copper container. When shopping for an angel’s trumpet, choose the genus Brugmansia over the genus Datura for training as a standard, as the brugmansia angel’s trumpet has a woodier habit that makes a convincing tree. While the plant is still young, prune away side shoots to allow a strong central leader to form. A brugmansia angel’s trumpet may reach eight feet in height at maturity, but container-grown specimens usually top out at a more manageable six feet. Angel’s trumpets start blooming in late summer, and the evening fragrance is a knockout, drawing legions of hummingbird moths. All plants in the angel’s trumpet category are extremely toxic, and gardeners are wise to wear impervious gloves when pruning or otherwise interacting with these exotic plants.
