When it comes to tropical gardens, size doesn't matter. A sense of dense, crowded plant life is exactly what you're trying to achieve, and side yards offer the shelter that suits many tropical-style plants. Tropical gardens are all about foliage -- large leaves, interesting textures and unusual shades -- and the occasional burst of strong color. Many tropical plants grow well in containers, allowing you to overwinter tender specimens inside, rework your design and move plants out of the way when the kids are wheeling their bikes through.
Ground cover plants enhance tropical style from the ground up, providing weed control, moisture retention and a verdant canvas for showier plants. Mondo grass (Ophiopogon japonicus) grows in clumps of rich green grassy stems 12 to 15 inches tall and wide. Suitable for U.S. Department of Agriculture plant hardiness zones 6 through 11, this evergreen also bears tiny lilac summer flowers. For areas with cold winters, wintercreeper (Euonymus fortunei "Kewensis") withstands icy conditions well, growing best in USDA zones 4 through 9. Bearing small, white-veined green leaves, this evergreen grows 2 to 6 inches high. Both plants spread slowly and won't take over a small side yard.
Creating the illusion of a tropical forest, medium-sized structural plants are the backbones of garden designs in small garden areas. Red leaved banana (Ensete ventricosum "Maurelii") bears large, lush, wine-red leaves and grows quickly to 12 to 15 feet tall and 8 to 10 feet wide. Although this plant is only hardy in USDA zones 10 through 11, it grows well in large containers and can be sheltered indoors for winter. Windmill palm (Trachycarpus fortunei) grows in USDA zones 7 through 10, and grows 8 to 10 feet tall and 4 to 6 feet wide. Bearing large, fan-shaped palm leaves, it performs best in partial shade.
Tropical gardens feature plants with unusual foliage that provide long-term interest. "Sun Power" plantain lily (Hosta x "Sun Power") bears golden, twisted leaves in clumps 18 inches tall and 36 inches wide, and in early summer it produces purple flower spikes 36 inches tall. Suitable for USDA zones 4 through 8, this perennial prefers a shady spot. Japanese painted fern (Athyrium niponicum var. pictum), hardy in USDA zones 3 through 8, bears variegated maroon-ribbed fronds in slowly spreading clumps 12 to 18 inches tall and 18 to 24 inches wide. This fern's silvery hues brighten the partial to full shade spots it prefers.
Two or three rich splashes of color add the finishing touch in small side yard tropical gardens. Mandevilla (Mandevilla x amabilis) bears yellow-throated, deep pink flowers and grows as a vine up to 10 feet long in USDA zones 10 through 11, or as a 3-foot-tall container plant in colder zones, where it can be overwintered in a sunny room indoors. "Storm Cloud" lily of the Nile (Agapanthus x "Storm Cloud") is another plant that suits container growing. Restricted roots prompt this shrub to produce its clusters of large, long-lasting violet-blue flowers on stalks 3 to 5 feet tall. Suitable for USDA zones 7 through 10, lily of the Nile grows best in full sun.