How to Care for Four O'Clock

Four O'Clock (Mirabilis jalapa) is an easy, bushy, fast-growing flowering plant named for its fragrant, trumpet-shaped blooms that typically open in the late afternoon and stay open through the evening. A single plant can bear flowers in several colors at once, and it forms a rounded, shrub-like mound over a season.

Light

Grow in full sun to part shade. Full sun yields the most abundant flowering and the densest, most compact plants, while a little afternoon shade is fine and can help in very hot climates. The flowers famously open in the cooler light of late afternoon and on overcast days.

Water

Water needs are moderate, and plants become quite drought-tolerant once established, thanks to a thick tuberous root. Keep young plants watered as they settle in, then water when the top inch or two of soil dries. Deep, occasional watering suits it better than frequent shallow sips. Avoid soggy soil, which can rot the tubers.

Soil & Potting

Four O'Clock is undemanding about soil and grows in average, well-drained garden soil across a range of textures. It tolerates poorer ground but rewards moderately fertile, loose soil with lush growth. Ensure good drainage, especially where tubers overwinter. In containers, use a quality potting mix in a roomy pot to give the tuber space.

Humidity & Temperature

This is a warm-season, heat-loving plant that thrives in summer warmth and average humidity. It is frost-tender; foliage is killed by frost, though in mild-winter regions the underground tuber survives to resprout. In colder zones it is grown as an annual or the tubers are lifted and stored dry over winter.

Feeding

Feed lightly. Rich soil or a modest application of balanced fertilizer in spring and midsummer keeps it blooming, but heavy nitrogen produces leggy growth with fewer flowers. A topdressing of compost at planting is often all it needs. Container plants benefit from occasional dilute liquid feeding through the growing season.

Propagation

Propagate easily from its large, hard seeds, which sprout readily when sown after the soil warms; nick or soak them to speed germination. It also self-sows generously. Additionally, the tuberous roots can be dug, divided, and replanted, and stored tubers can be started to get a head start on the season.

Repotting / Pruning

Little pruning is needed. Pinch young plants to encourage bushiness, and trim back straggly growth to keep the mound tidy. Deadheading is optional; removing spent flowers and developing seed reduces prolific self-seeding if that is a concern. For potted plants, repot or divide the tuber when it outgrows its container.

Common Problems & Pests

Four O'Clock is generally robust and pest-resistant. Occasional issues include aphids, whiteflies, and leaf-chewing beetles such as Japanese beetles, along with rust or leaf spot in humid, crowded conditions, and root rot in waterlogged soil. Good spacing, sun, and drainage prevent most trouble. Its main nuisance is enthusiastic self-seeding, easily managed by removing seed heads.

Seasonal Care Tips

Sow seed or plant tubers after the last frost once soil is warm. Through summer, water during dry spells and enjoy the fragrant evening display; deadhead if you want to curb reseeding. As frost approaches in cold climates, either treat plants as annuals or cut back and lift the tubers to store in a cool, dry, frost-free place for replanting in spring.