Four O'Clock

Four o'clocks are remarkably easy to grow from their large, round black seeds. Direct sow seeds outdoors after the last frost date, planting one inch deep and twelve to eighteen inches apart in full sun. Seeds germinate quickly in seven to ten days when soil is warm. In colder regions, start seeds indoors three to four weeks before the last frost in individual pots for earlier blooms.

These plants thrive in average to poor, well-drained soil and tolerate heat and drought once established. Rich soil produces larger, bushier plants that may reach three to four feet tall and wide. Water regularly during establishment, then reduce to occasional deep watering. Four o'clocks are not fussy about soil pH and adapt to a wide range of conditions.

The tuberous roots can be dug and stored over winter in zones where they are not hardy, much like dahlias. In zones 7 and above, the roots often survive winter underground and resprout in spring. Plants also self-sow abundantly from dropped seeds. All parts of the plant are considered toxic, so wear gloves when handling seeds and keep away from children and pets.

Mirabilis jalapa, commonly known as the four o'clock flower or marvel of Peru, is native to tropical regions of Central and South America, with its center of origin believed to be in the Andes mountains of Peru and neighboring countries. The Aztec and Inca civilizations cultivated this plant long before European contact, valuing it for both its ornamental beauty and its medicinal properties. Indigenous peoples used preparations from the roots, leaves, and seeds to treat a variety of ailments including wounds, digestive disorders, and skin conditions. Spanish conquistadors encountered the plant during the sixteenth century and were captivated by its unusual trait of producing differently colored flowers on a single specimen. They brought seeds back to Europe around 1540, where the plant quickly gained popularity in monastery and apothecary gardens across Spain, Italy, and southern France. The Swedish botanist Carl Linnaeus formally described the species in 1753, choosing the genus name Mirabilis, meaning 'wonderful' or 'miraculous' in Latin, in reference to the astonishing color variation found within individual plants. By the seventeenth century, four o'clocks had spread along trade routes to Asia, becoming deeply integrated into the garden traditions of Japan, China, India, and the Philippines. The plant played a notable role in the history of genetics when German botanist Carl Correns used it in 1909 to demonstrate non-Mendelian cytoplasmic inheritance, showing that leaf color patterns were inherited exclusively through the maternal parent. Today, Mirabilis jalapa is naturalized in tropical and subtropical regions worldwide and is grown as an annual in temperate climates. It remains a beloved cottage garden plant valued for its ease of cultivation, vibrant evening blooms, and sweet fragrance that fills the garden at dusk.

Four o'clocks are undemanding about soil and grow in almost any well-drained garden soil with a pH of 6.0 to 7.0. They actually flower more freely in average to lean soil. Overly rich soil promotes excessive vegetative growth at the expense of blooms. A single application of balanced granular fertilizer at planting time is sufficient. Container plants benefit from light monthly feeding with diluted liquid fertilizer. Good drainage is the most important soil requirement.

Four o'clock flowers are best enjoyed on the plant, as they wilt quickly when cut. For seed saving, collect the large, round, black seeds that drop to the ground beneath plants in late summer and fall. Seeds are easy to spot and gather by hand. Dry seeds for a few days on a paper towel before storing. The tuberous roots can be dug in fall before frost, dried for a day, and stored in peat moss in a cool location for replanting the following spring.

Four o'clocks are not suitable for cut flower arrangements due to their short bloom cycle and quick wilting. Seeds store excellently in paper envelopes in a cool, dry place for three to five years. Tuberous roots should be dug after the first light frost, dried briefly, and stored in barely moist peat moss or vermiculite at 50 to 55 degrees Fahrenheit over winter. Replant tubers in spring after the last frost for earlier and more vigorous blooming than seed-started plants.