Four o'clock
Also known as
Marvel of Peru, Belle de nuit, Don Diego de noche, Four o’Clock Flower, Clavillia
Keep this plant’s care guide close at hand.
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Mirabilis jalapa is a fast-growing, tuberous perennial often grown as an annual outside mild climates. Its common name, Four o’clock, refers to the fragrant, trumpet-shaped flowers that unfurl in late afternoon and close the following morning, attracting nocturnal moths. Plants form bushy clumps 60–120 cm tall with opposite, ovate leaves and fleshy, carrot-like tubers that store energy for seasonal regrowth. Remarkably, a single plant can bloom in multiple colors—magenta, yellow, white, or bi-colored and mottled—owing to genetic chimerism and pigment instability. It thrives in poor to moderately fertile, well-drained soils and tolerates heat and short dry spells once established. In frost-free zones it behaves as a perennial; elsewhere, it dies back with cold and is easily raised from seed or overwintered as lifted tubers. While generally low-maintenance, it can self-seed prolifically and become weedy in suitable climates. All parts, especially seeds and roots, can be toxic if ingested. Its long summer-to-fall bloom and evening perfume make it a classic cottage and night-garden plant.
Taxonomy
Properties & Requirements
How to care for Four o'clock
Water
Water deeply and infrequently to encourage robust tubers. In the first growing season, keep soil evenly moist, allowing the top 2–3 cm to dry between waterings. Established plants tolerate short dry periods but bloom best with consistent moisture. Avoid soggy conditions; ensure sharp drainage in containers and raised beds. Mulch 2–5 cm to moderate soil moisture and temperature, keeping mulch off stems. As foliage yellows toward dormancy, reduce watering; keep stored tubers dry, only barely moist if shriveling.
Light
Provide full sun for the heaviest bloom—aim for 6–8+ hours of direct light daily. In very hot, arid climates, light afternoon shade reduces stress without sacrificing flowers. Plants tolerate bright partial sun but may become leggier and flower less with under 4–5 hours of direct light. Indoors (temporary culture), use a south- or west-facing window or high-output grow lights for 12–14 hours. Maintain open exposure with good air movement to discourage mildew in humid regions.
Nutrients
Mirabilis jalapa is not a heavy feeder. Mix compost into planting soil, then feed lightly during active growth (late spring to mid-summer) with a balanced fertilizer (e.g., 10-10-10) at half rate every 4–6 weeks. Excess nitrogen promotes leafy growth at the expense of flowers, so favor modest, bloom-supporting nutrition with slightly higher phosphorus and potassium if soil is poor. Container plants benefit from a slow-release fertilizer at planting. Stop fertilizing as nights cool and growth slows. Do not feed dormant tubers.
Temperature
Best growth occurs in warm conditions, 18–30°C. Flowers and foliage are damaged by frost; top growth typically dies near 0°C. In USDA Zones ~7–11, tubers may overwinter in-ground with mulch; in colder zones, lift and store tubers dry at 5–10°C. Start seeds or potted tubers after danger of frost and when soils warm above ~15°C. Heat-tolerant when watered, but container plants can overheat—provide afternoon shade and maintain airflow during prolonged heat waves.
