There are at least 269 perennials that bear flowers and are suitable for garden use. According to Cornell University, these are categorised as flowering perennials and live for at least two-plus years; most live for much longer. Some of these perennials will bloom year round under certain conditions, which include climates that are warm 365 days a year, indoors in containers and in greenhouse gardens.
Also known as the Rose of China, hibiscus can bloom all year, in indoor containers or outdoors in USDA plant hardiness zones 9 and 10, with only periodic breaks between flowering episodes. Growing naturally in tropical climates, hibiscus like lots of water in well-drained and fertilised soil, sunlight and warmth, but not dry heat. Prune hibiscus regularly or they will grow up to 5 feet tall; pruning also encourages flowering. Blooms are white, pink, yellow, orange and red, and foliage is deep, lush green. Aphids and spider mites can be a problem for hibiscus, and the plants are prone to becoming root-bound if the pot size isn't graduated when necessary. They will also drop leaves and buds if conditions are too dry, temperature extremes occur, or they do not get enough sunlight.
In certain warm climates, roses will bloom year round. Roses do well in beds and containers and come in two varieties: old garden and shrub roses that are low-maintenance, and high maintenance modern roses, similar to the ones purveyed by florists. Roses in both categories come in almost every flower colour, rose-flower size and have varying degrees of fragrance. In general, roses need prolonged, direct sunlight daily, especially in the morning, are intolerant of salty soils, and prefer well-drained, moderately acidic soil. To keep your roses blooming all year, protect them from cold snaps and prune them per the directions of your area master gardener help desk.
African violets have dozens of bloom colours, leaf shapes and hues. Although these plants are considered "speciality" plants according to the Alabama Cooperative Extension System and usually containerised in homes and greenhouses, they can grow in the ground in USDA plant hardiness zones 7 to 10 and will even take over a garden in the right climate. Despite their reputation for being difficult to grow, horticulturists indicate they are fairly easy to maintain. They don't like direct sunlight; filter light through other plants for best results. Southern and eastern exposures are much too hot for African violets in the summer, so keep them in the western and northern windows or gardens. They like light and airy soil, so a combination of peat moss and perlite works well. Always remove dead blooms and leaves when watering and repot in a larger container when the outer leaves start to die off. African violets will root in water from a single leaf.
- Alabama Cooperative Extension System: Hibiscus: A Plant That Blooms All Year
- University of Florida IFAS Extension: Growing Roses in Florida
- University of New Hampshire Cooperative Extension: African Violets Can Bloom All Year Long
- U.S. National Arboretum: USDA Plant Hardiness Zone Map
- Alabama Cooperative Extension System: Hobby Greenhouse Construction