Many types of geraniums (Pelargonium spp.) grow well indoors in south windows. Zonal geraniums (P. x hortorum), the common pot and bedding geraniums, make good hanging baskets for sunny areas. Keep them deadheaded to encourage rebloom. Scented geraniums need the full sun of a southern exposure to develop the volatile oils that scent the leaves. Ivy geraniums (P. peltatum) and Martha Washington hybrids grow well in southern and western exposures during the cooler months but should be moved to an east or north window in summer.
Grown for their extravagantly colored and variegated leaves, coleus (Coleus x hybridus) used to be strictly a shade plant, but recently breeders have introduced sun-loving cultivars that need full sun to develop their bright colors. Sun-loving cultivars include Alabama Sunset, with yellow-edged, red leaves, and Burgundy Sun, a large cultivar with burgundy-red, heart-shaped leaves. Pineapple has lime-gold leaves with red stems, while Plum Parfait has ruffled, purplish-plum leaves with pink margins. The Solar series comes in many colors, all of them suitable for full-sun baskets. Keep coleus baskets moist but not soggy, and pinch back any flower stalks that form to keep the plant bushy.
Allamanda (Allamanda cathartica), also called golden-trumpet, is a tropical vine grown for its bright yellow flowers. Several cultivars are available, including the double-flowered Flore Pleno. In hanging baskets, allamanda not only trails but some stems also wind themselves around the hanging chains. Cut back straggly plants, as they'll quickly rejuvenate themselves. Note that allamanda is poisonous, so use it with caution if there are small children or pets in your household.
Bougainvillea (Bougainvillea hybrids) are woody, tropical vines often used in Florida and the Southwest as landscape plants to hide unsightly walls. They make lovely hanging baskets in the rest of the country. Their colorful flowers, usually in shades of pink or yellow, are actually modified leaves, called bracts, which draw attention to the true, small white flower inside. Bougainvilleas need full sun and warmth to flower, so a south-facing window is the perfect indoor location. They grow best in well-drained, rich soil that's slightly acidic, so add some peat moss into the potting mixture. Allow the soil to dry slightly between waterings, but don't let the plants wilt or get bone-dry.
Annual vinca (Catharanthus roseus) makes a good hanging basket for sunny windows, but the plants are usually available in garden centers only in late spring and early summer. Heliotropes (Heliotropum arborescens) have cherry-pie-scented purple or lavender blooms. The silver-leaved licorice plant (Helichrysum petiolare) is often included in mixed containers but makes a lovely hanging basket on its own. Chenille plants (Acalpha hispida), with their fuzzy red flowers, are old-fashioned indoor plants enjoying a new surge of popularity; they thrive in sunny windows. And don't forget wax begonias (Begonia semperflorens), a standby bedding plant that's also a good choice for hanging baskets.