Four o’clock flower (Mirabilis jalapa), also known as the marvel of Peru, is a perennial, herbaceous, bushy plant with fragrant, showy flowers, commonly cultivated for ornamental purposes. During bloom time, its flowers are closed most of the day; they open between four and eight o’clock, hence the common name four o’clock flower.
I. Appearance and Characteristics
Mirabilis jalapa, the marvel of Peru or four o’clock flower, is the most commonly grown ornamental species of Mirabilis plant, and is available in a range of colors. Mirabilis in Latin means wonderful and Jalapa (or Xalapa) is the state capital of Veracruz in México. Mirabilis jalapa was cultivated by the Aztecs for medicinal and ornamental purposes.
Mirabilis jalapa is native to the dry tropical regions of North, Central and South America: Mexico, Guatemala, Chile and Peru. This plant has been introduced for ornamental purposes and has become naturalized throughout tropical, subtropical and temperate regions of the world.
It is a perennial, herbaceous, bushy plant that reaches stature heights of mostly 1 meter, rarely up to 2 meters, in height. It may also be grown as an annual, especially in the temperate zone. The single-seeded fruits are spherical, wrinkled and black upon maturity, having started out greenish-yellow. The stems are thick, full, quadrangular with many ramifications and rooting at the nodes. The posture is often prostrate.
A curious aspect of M. jalapa is that flowers with different colors grow simultaneously on the same plant. Additionally, an individual flower can be splashed with different colors. Flower patterns are referred to as sectors (whole sections of flower), flakes (stripes of varying length), and spots. A single flower can be plain yellow, red, magenta, pink, or white, or have a combination of sectors, flakes, and spots. Furthermore, different combinations of flowers and patterns can occur on different flowers of the same plant.
Usually, the flowers are yellow, pink and white, but a different combination of flowers growing on the same single four o’clock plant can be found. Another interesting point is a color-changing phenomenon. For example, in the yellow variety, as the plant matures, it can display flowers that gradually change to a dark pink colour. Similarly, white flowers can change to light violet. Despite their appearance, the flowers are not formed from petals – rather they are a pigmented modification of the calyx. Similarly, the ‘calyx’ is an involucre of bracts. The flowers are funnel-shaped and pentalobed, they have no cup (replaced by bracteal leaves) but are made of a corolla.
The inflorescences contain three to seven unpopped flowers. Earning the name “four o’clock flower”, the fragrant flowers open in the late afternoon or early evening, and also in overcast weather, and exhale a scent reminiscent of the tobacco flower, and attract moths for pollination. The anthesis lasts from 16 to 20 hours and thus remains a visible part of the day. The flowers are pollinated by long-tongued moths of the family Sphingidae, such as the sphinx moths or hawk moths and other nocturnal pollinators attracted by the fragrance.
The plant does best in full sun. Often in the sun the leaves wither, then return vigorously in the evening, when temperatures start to fall and the sun sets. It cannot stand the cold as the aerial part, with the first frosts, deteriorates and can die, but the underground part that can return to vegetate in spring remains vital. The plant will self-seed, often spreading rapidly if left unchecked in a garden. Some gardeners recommend that the seeds should be soaked before planting, but this is not totally necessary. In North America, the plant perennializes in warm, coastal environments, particularly in USDA zones 7–10. The plant is easy to grow, as long as it is sunny or partially shaded. Under these conditions, it grows very quickly.
It grows preferably in light soil, rich in humus and well draining, it is neutral side acidity (pH). Pot cultivation is always possible with a mixture of 80% soil and 20% garden soil and a very deep container with the tubers being put at a depth of 10 cm. It is usually sown from mid-February to May. The seeds germinate rapidly at a temperature of 18 °C.
II. How to Grow and Care
Sunlight
Four o’clocks thrive in full sun, meaning approximately six hours of direct sunlight on most days. They will tolerate partial shade, though the plants might become somewhat leggy and not bloom as profusely in locations that are too shady.
Temperature and Humidity
Four o’clock plants thrive in warm temperatures and are often grown as annuals in cooler climates outside of their growing zones, where the plants die once frost and cold fall temperatures arrive. Humidity typically isn’t an issue for them as long as adequate soil moisture is maintained.
Watering
Do not let these plants dry out; water whenever the top 1 to 2 inches of soil becomes dry. But avoid overwatering, as soggy soil can cause root rot. Mulching around the plants can help to keep the soil sufficiently moist. Plants grown in containers will generally need more regular watering than those in the ground.
Soil
These plants can grow in a variety of soil types. But rich, loamy, well-drained soil is ideal. And a neutral to slightly acidic soil pH is best.
Fertilizing
Apply a balanced fertilizer in the spring, and continue to feed monthly until fall. However, if you already have rich soil, you might only need to give your plants the one spring feeding.
Pruning
Pinch back the main shoot when the plant is young to promote a bushier growth habit and more flowering. In dry weather, when the plants can get a little ragged looking, a shearing back by about a third will refresh them.
How to Grow From Seed
These plants can be sown directly in the garden in the spring once the danger of frost has passed. For best germination, soak the seeds overnight in water. Then, plant the seeds about 1/4 inch deep in your garden soil. You also can start seeds indoors roughly six to eight weeks prior to your area’s projected last frost date. Plant them in a seed-starting mix about 1/4 inch deep, and place them by a light source. Keep the soil moist but not soggy as you wait for seedlings to appear.
Furthermore, chances are good that if you allow your plants to go to seed in the fall, they will self-seed in the garden, especially in warmer zones. Seedlings can be easily uprooted and moved to another location if you wish.
Overwintering
After the plant is done blooming in the fall, the tuberous roots can be dug up and stored for winter in a cool (but not freezing), dark location. Replant them the following spring once temperatures are reliably above freezing. If you live within the plant’s growing zones, the tubers can stay in the ground for winter.
Pests and Diseases
Common Diseases
Four o’clocks tend to be very pest- and disease-resistant. However, rusts (white rust and brown rust) and some leaf spot diseases can affect the foliage. The best solution for areas prone to rust bacteria is to follow integrated pest management practices, such as discarding affected plants, applying fungicide to stored tubers, and rotating plants from year to year.
Common Problems
Four o’clock plants are generally healthy when grown in conditions they like. However, some common issues can arise in subpar environments.
Curling Leaves
Both pests and diseases can cause curling leaves on a plant. Aphids are a common culprit of curling leaves on four o’clocks, as these tiny insects suck the sap out of the leaves. They often can be knocked off the plant with a strong stream of water from a hose, or you can use insecticidal soaps.
Plant Not Blooming
If your plant doesn’t seem to be blooming at all, heat might be the reason. While four o’clocks generally bloom around 4 p.m., they might wait until later in the evening if the weather is extremely hot. So your plant might still bloom overnight; you just might not see it. Very nutrient-poor soil also can result in sparse blooms. Have a soil test done to make sure your soil has enough phosphorus, which aids in flowering.
III. Uses and Benefits
Ornamental uses
The four o’clock flower is typically grown in borders, beds, and containers of cottage and Mediterranean gardens. In addition, it can be used as a flowering shrub for landscape purposes when planted close together. They are well paired with Asiatic lilies, French marigolds, and Nasturtium.
Other uses
- The flowers are used in food colouring. The leaves may be eaten cooked as well, but only as an emergency food.
- An edible crimson dye is obtained from the flowers to color cakes and jellies.
- In herbal medicine, parts of the plant may be used as a diuretic, purgative, and for vulnerary (wound healing) purposes. The root is believed to be an aphrodisiac as well as having diuretic and purgative properties. It is also used in the treatment of dropsy.
- The leaves are used to reduce inflammation. A decoction of them (by mashing and boiling) is used to treat abscesses. Leaf juice may be used to treat wounds. The bulbous roots of the flower have a laxative effect.
- Powdered, the seed of some varieties is used as a cosmetic and a dye. The seeds are considered poisonous.
- The plant has a potential for the bioremediation of soils polluted with moderate concentrations of heavy metals such as cadmium.
- In Brazil, the Indian Kayapo sniff the powder of dried flowers to cure headaches and use the root decoction to wash wounds and treat skin conditions such as leprosy. In Peru, juice extracted from flowers is used for herpes lesions and earache. The juice extracted from the root is used to treat earache, diarrhea, dysentery, syphilis and liver infections. In Mexico, decoctions of the whole plant are used for dysentery, infected wounds, and bee and scorpion stings.
- Flower extract can be used as a natural pH indicator in acid–base titration. This was found and demonstrated to be both economical and accurate by Shishir et al. 2008.
- Some studies suggest that M. jalapa is an ancient introduction to the Himalayan region.
IV. Types of Four O’Clock Plants
There are several types of four o’clocks:
- Mirabilis jalapa ‘Alba’ is a white variety with a light citrus scent that freely self-seeds.
- Mirabilis jalapa ‘Jingles’ produces small, multicolored flowers.
- Mirabilis jalapa ‘Kaleidoscope’ flowers are multicolored pink, yellow, and white with interesting splashes and streaks
Find Where to Buy the Best Four o’clocks (Mirabilis jalapa)
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