- Evergreen shrubs
- Zones vary by species
- Full sun or partial shade
- Regular water
No plant expresses the grace of the South better than gardenia. Intensely fragrant white blossoms contrast beautifully with shiny, leathery dark green leaves. Double forms are classic corsage flowers. In borders, gardenias need good drainage and acid soil containing lots of organic matter. Plant them high (like azaleas and rhododendrons) and don’t let them be crowded by other plants or competing roots. Mulch plants instead of cultivating; feed every 3 to 4 weeks during the growing season with acid fertilizer, fish emulsion, or blood meal. Prune to remove straggly branches and faded flowers. Control whiteflies, aphids, and other sucking insects with light horticultural oil.
Gardenias do well in large pots on decks and patios; gardeners in cold-winter areas can grow them in cool greenhouses. Unfortunately, they make poor houseplants— they attract mites, mealybugs, and whiteflies.
G. jasminoides (G. augusta). COMMON GARDENIA, CAPE JASMINE. Zones LS, CS, TS, except as noted; 12–8. Native to China, Taiwan, Japan. Glossy bright green leaves and usually double white flowers to 3 in. across. Hardy to about 10°F. Will survive 0°F but is likely to die back to roots.
The many selections are useful in containers or raised beds, as hedges, espaliers, low screens, or single plants.
‘Aimee’ (‘First Love’). Somewhat larger shrub than ‘August Beauty’, with larger flowers. Spring bloom.
‘August Beauty’. Grows 4–6 ft. high and 3–4 ft. wide. Blooms heavily midspring into fall. Large double flowers.
‘Chuck Hayes’. Extra-hardy type, possibly as hardy as ‘Klein’s Hardy’. To 4 ft. high and wide. Double flowers in summer, heavy rebloom in fall.
‘Golden Magic’. Reaches 3 ft. tall, 2 ft. wide in 2 to 3 years, eventually larger. Extra-full flowers open white, gradually age to deep golden yellow. Blooms from spring through summer, peaking in midspring.
‘Grif’s Select’. Compact, 3–4 ft. tall and wide; profuse single flowers in late spring and early summer, red seed capsules in fall. Hardy to about 5°F.
‘Kimura Shikazaki’ (‘Four Seasons’). Compact plant 2–3 ft. tall. Flowers similar to those of ‘Veitchii’, but slightly less fragrant. Extremely long bloom season—spring to fall.
‘Klein’s Hardy’. For cold-winter areas; hardy to 0°F. To 2–3 ft. high and wide. Single flowers in summer. Grow in a wind-protected site.
‘Miami Supreme’. Grows to 6 ft. tall and wide, with large double flowers (4–6 in. wide) in spring, periodic flowering through summer.
‘Mystery’. Best-known selection. Bears 4- to 5-in. double flowers from mid- to late spring or longer. Tends to be rangy and needs pruning to keep it neat. Can reach 6–8 ft. high and wide.
‘Radicans’ (‘Prostrata’). Grows 6–12 in. tall and spreads to 2–3 ft., with small leaves; inch-wide double flowers bloom in summer. Good for small-scale ground cover or pots. Not as cold hardy as the species; not well suited to Middle South. ‘Radicans Variegata’ (‘Prostrata Variegata’) has gray-green leaves with white markings.
‘Shooting Star’. Upright grower to 6–8 ft. tall and wide, with large leaves and single flowers in late spring and early summer. Hardy to 0°F.
‘Veitchii’. Compact, reliable grower to 3 1/2–4 1/2 ft. tall and 6 ft. wide. Blooms prolifically from midspring into fall (and sometimes even during warm winters), bearing fully double 1- to 1 1/2-in. flowers.
‘White Gem’. At just 1–2 ft. tall and wide, this selection is useful for edgings, containers, or raised beds, where the fragrance of its single, creamy white summer flowers can be appreciated.
G. thunbergia. STARRY GARDENIA. Zones TS; 12–8. Native to South Africa, this winter bloomer is much less common than G. jasminoides, because it is less cold hardy and not as showy. Sometimes grown as an ornamental in south Florida. Primary use is as a rootstock to impart nematode resistance and increased vigor to G. jasminoides. Reaches 15 ft. tall and as wide. Dark green leaves to 6 in. long; single, 3- to 4-in., white- to cream-colored flowers with a long tube and typically eight overlapping, petal-like lobes.