Wildflower/Perennial
Four o'clock
Mirabilis jalapa · Nyctaginaceae
Also called: Marvel of Peru, Beauty-of-the-night, Maravilla
Four o'clock (Mirabilis jalapa) is a low-water wildflower/perennial well suited to Tucson and the low desert.
Four o'clock at a glance
- Water use
- Low (established)
- Sun
- Full sun for best flowering; tolerates light afternoon shade in Tucson, which can reduce midday wilting in extreme summer heat.
- Mature size
- 2-3 ft. tall and 2-3 ft. wide as a bushy mound (can reach 3-4 ft. with ample water).
- Growth rate
- Fast in warm weather; dies back with frost and regrows quickly from the tuber.
- Bloom
- Magenta, pink, red, yellow, white, or bicolored/striped; flowers can vary on the same plant., Late spring through fall in Tucson; flowers open in late afternoon (around 4 p.m.) and evening and are fragrant and night-pollinated.
- Cold hardiness
- Frost-tender top growth (damaged at/below 32°F) but the tuberous root is hardy in Tucson (USDA 9a-9b) and reliably returns as a perennial; grown as an annual in colder zones.
- Soil
- Adaptable; tolerates poor, alkaline desert soils. Prefers well-drained soil but is not fussy.
- Native range
- Tropical South America (Peru/Andes region); long naturalized across warm regions. Note: a related native four o'clock, Mirabilis multiflora, is Sonoran/Southwest native, but M. jalapa is not.
- Best used as
- Cottage and informal beds, Evening/fragrance gardens, Hummingbird and moth gardens, Low-water summer color, Screening/filler shrub-like perennial
- Wildlife
- Evening flowers attract hawk (sphinx) moths and hummingbirds; nectar source. Self-sows readily.
- Toxicity
- Toxic if ingested. Seeds and roots contain irritant compounds (trigonelline and others); ingestion can cause stomach pain, vomiting, and diarrhea in pets and children, and sap may irritate skin. Keep seeds away from kids and pets.
How to grow Four o'clock in Tucson & the low desert
Watering
Drought tolerant from its large tuberous root once established. In Tucson, water deeply about weekly in summer and every 10-14 days in spring/fall; it can survive on much less but looks lusher with regular summer water. Cut back watering in winter dormancy.
Fertilizer & nutrients
Low feeder. A single spring application of balanced slow-release fertilizer or compost is plenty; excess nitrogen produces foliage at the expense of bloom.
Pruning & care
Cut frost-killed top growth to the ground in winter; it resprouts from the tuber in spring. Shear lightly to shape and remove spent growth. Deadhead or shear to limit prolific self-seeding if reseeding is unwanted.
Notes
Vigorous, heat-loving summer perennial that thrives in Tucson once the tuber is established. Reseeds prolifically and forms a large carrot-like tuber that can be lifted and stored. Give room to spread; can become weedy if allowed to self-sow freely.
Sources: University of Arizona / Pima County Cooperative Extension; Arizona-Sonora Desert Museum (desertmuseum.org); AMWUA / Water Use It Wisely (wateruseitwisely.com)