Four O'Clock

A bushy annual with fragrant trumpet flowers that open in late afternoon and close the following morning, available in many colors. Four o'clocks form tuberous roots and self-sow readily, often behaving as perennials in warm climates. They are easy to grow, drought-tolerant, and attract hawk moths with their evening fragrance.

The large seeds are easy to handle and ideal for beginner gardeners. Direct sow one inch deep after all frost danger has passed, spacing twelve to eighteen inches apart. Seeds germinate in seven to ten days in warm soil above 65 degrees Fahrenheit. For earlier blooms, start indoors three to four weeks before the last frost in individual pots. Soaking seeds overnight in warm water speeds germination. Thin direct-sown seedlings to the strongest plant per station. Save seeds easily by collecting the hard black seeds from the ground beneath plants in fall.

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.

Four o'clocks are ideal companions for moonflowers and nicotiana in evening and night gardens designed for fragrance. Their bushy growth provides a backdrop for lower-growing annuals. They pair well with ornamental grasses and late-blooming perennials. The flowers attract hawk moths and other nocturnal pollinators, benefiting the entire garden ecosystem. Plant near outdoor seating areas to enjoy the evening fragrance, but keep away from vegetable gardens due to toxicity.

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.

Ideal Temperature

Hardiness Zone Compatibility

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.

Storage & Preservation

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.

Troubleshooting Common Problems

The primary challenge is controlling four o'clocks' aggressive self-sowing, which can overtake garden beds in warm climates. Remove spent flowers before seeds drop to limit spreading. Plants can become very large and bushy, overwhelming smaller neighbors if not given adequate space. The flowers only open in late afternoon, which disappoints gardeners who are away during evening hours. All plant parts are toxic, making this a poor choice for gardens frequented by small children or pets.

Growing Tips

1. Soak the hard, dark seeds in warm water for twelve to twenty-four hours before planting to soften the seed coat and speed up germination by several days.
2. Choose a planting location that receives full sun for at least six hours daily, though four o'clocks will tolerate light afternoon shade in extremely hot climates.
3. Space plants eighteen to twenty-four inches apart to allow for their naturally bushy growth habit, which can reach two to three feet wide at maturity.
4. Four o'clocks are remarkably drought tolerant once established thanks to their tuberous roots, but consistent weekly watering during bloom season produces the most flowers.
5. Avoid over-fertilizing with nitrogen-heavy products, which promotes excessive leafy growth at the expense of flowers. A balanced or phosphorus-rich fertilizer works best.
6. Pinch the growing tips of young plants when they reach eight to ten inches tall to encourage branching and create a fuller, more compact plant shape.
7. In USDA zones 6 and colder, dig up the tuberous roots after the first fall frost, allow them to dry for a day, then store them in peat moss at 45 to 55 degrees Fahrenheit.
8. Four o'clocks self-seed aggressively in warm climates. Deadhead spent flowers before seeds mature if you want to prevent volunteer plants from spreading into unwanted areas.
9. These plants have very few pest problems, but watch for Japanese beetles in midsummer. Hand-pick beetles in the early morning when they are sluggish for effective organic control.
10. Plant four o'clocks near patios, porches, or bedroom windows to enjoy their intense sweet fragrance during evening hours when the flowers are fully open and most aromatic.