Overview of Four O’Clock
The common name “four o’clock” was given to Mirabilis jalapa because its flowers do not open until late in the day. This old-fashioned garden ornamental in the Nyctaginaceae family is a tender perennial hardy to zone 9a commonly grown as an annual in temperate climates. Native to tropical North, Central, and South America, it is the most commonly grown ornamental species of Mirabilis. Another common name for the species is Marvel of Peru.
Identified by Europeans in 1540, the root was used by indigenous peoples for medicinal purposes and as a purported aphrodisiac, while the flowers produce an edible red dye for coloring food. Note, however, that the roots and seeds are both somewhat toxic and plants can cause contact dermatitis in susceptible individuals.
The shrub-like, erect and spreading, multi-branched plants grow 2-3 feet tall and wide. The weak and brittle stems break easily and flop over if not supported. Stems are light or bright green but may have a yellow or pink hue. The opposite, ovate, bright green leaves are up to 4 inches long with a pointed end.
Leaves are triangular to egg-shaped to lance-shaped, with smooth (non-toothed) edges. The plants produce elongated, dark-colored, swollen to tuberous taproots that can be a foot or more long and weigh up to 40 pounds in climates where they are perennial.
Flowers are produced in bright and pastel shades of white, yellow, pink, magenta, and red. Flowers of different colors can be found on the same plant – either simultaneously or at different times – and flowers may even be bicolored, speckled, or variegated.
Four O’Clock blooms summer through fall and may have a strong, sweet-smelling fragrance when open (but sometimes lack a noticeable scent). Flowers are borne in terminal or axillary clusters of one to several flowers. The colorful, trumpet-shaped portion of the flower is the pigmented calyx or partially fused sepals; the flowers actually lack true petals. Each flower is about two inches long and abruptly flares out to about an inch across at the end with five lobes. These tubular flowers open late in the day or in the evening (although they will open earlier open earlier on rainy or very cloudy afternoons) as they are pollinated by sphinx moths (family Sphingidae) and other nocturnal pollinators with long tongues. Hummingbirds and butterflies are also attracted to the flowers.
The flowers wilt by the following morning and those faded flowers are not self-shedding and remain on the plant – an appearance that some people dislike. Numerous large, dark, leathery, 5-ribbed, spherical “seeds” (actually a fruit that is a nut-like achene) with a wrinkled surface are produced in the fall. These are poisonous if ingested, as are the roots. They can also self-seed under the right conditions and have become naturalized in some parts of the southern U.S.
Landscape Use of Four O’Clock
Grow four o’clock in full sun in almost any type of soil but they do best in a humus-rich, well-drained spot.
As these are tender plants, put transplants outside only after all risk of frost, about the same time you would plant tomatoes. Provide moderate moisture and fertilize periodically for the best growth. They have few pests and are not favored by deer. Tubers can be dug in the fall to store indoors and plant again in spring after the last frost. Treat the tubers like dahlias by digging them before the first freeze, shaking off the soil and storing them in dry, cool, frost-free conditions until spring.
This sturdy plant can be used as an annual hedge when planted close together. They are right at home in a cottage garden, in borders and beds, or can be added to large containers. If possible place them where the night-blooming flowers and fragrance can be appreciated. They combine nicely with Asiatic lilies, creating an interesting contrast of large and small flowers.
Propagating Four O’Clock
Four O’Clock seed can be sown directly outdoors after the danger of frost has passed or indoors up to 8 weeks ahead of time. Soaking the seeds in water overnight or nicking the surface speeds up germination. Plant the seeds about ¼ inch deep.
Seeds typically germinate in 5-7 days at 68 to 70 °F. Transplant seedlings when large enough to handle, if needed, into individual pots. Thin seedling or place transplants 12-24 inches apart.
Cultivars of Four O’Clock
There are some cultivars and hybrids of four o’clocks, although they are often offered just as ”Four O’Clocks”. Single color and mixed color options are available. Varieties include:
- ‘Broken Colors’ features bicolor flowers with striped, splashed, or marbled patterns in a range of attractive colors, including pink, red, white, and yellow
- ‘Jingles’ is a series with small, multi-colored flowers
- ‘Limelight’ has chartreuse foliage and vivid neon pink flower
- ‘Marbles’ series offers irregularly striped and splotched bicolor flowers in a range of colors, including White-Red (white with carmine), White-Yellow (white with light yellow), Yellow-Red (yellow with carmine), and Tricolor (tricolored flowers in a range of shades)
- ‘Salmon Sunset’ has unusual pinkish orange flowers
- The related Mirabilis longiflora (long-flowered four o’clock) has white flowers with elongated throats and an orange-blossom scent, growing 24 to 30 inches tall. This species is native to southern Arizona, Texas, and Mexico
– Susan Mahr, University of Wisconsin – Madison
Last Update: Allen R. Pyle, UW-Madison Extension, 2026
