Four O'Clocks


By Kim Willis These articles are copyrighted and may not be copied or used without the permission of the author.

Four O’Clocks 
(Mirabilis jalapa) are an old cottage garden flower that many modern gardeners no longer grow, and that’s a shame because these plants truly are the marvel their other common name, Marvel of Peru, suggests. In warmer zones they can spread quickly, but the gardener should merely gift them on to other gardeners or simply enjoy their bounty.

Four O’Clocks are native to South America, with Peru probably the place Europeans discovered them.  They were moved all around the globe however because of their herbal qualities and beautiful, strange flowers and have naturalized in many warmer countries.  They were being grown in English gardens by the late 1500’s and used in Chinese medicine long before that.

Four O’Clocks are perennial in zones 7b and above.  In the north the tuberous roots of Four O’Clocks can be dug and stored like dahlia bulbs.  But since they also bloom quickly from seed they can be treated like annuals in colder planting zones.

The marvel of Four O’Clocks flowers

Let’s start with the beautiful, often fragrant flowers of the Four O’Clock.  The flowers seen are actually formed by a colored, modified calyx, they don’t actually have petals, though that piece of information is just some trivia for you, you won’t notice the difference.  This may be the reason the flowers do their interesting color magic.  The flowers are long and trumpet shaped, flaring out to be about 1 ½ inches wide. 

Four O’Clock flowers come in red, white, yellow and pink and variegated.  Now here’s the interesting, magic thing.  The flowers on the same plant can be different colors, and plants may also change the color of their flowers over time, with the plant having white flowers when it begins to bloom and later in the season pink for example. When flowers are variegated- more than one color, the variegation is usually unique to each flower.  Variegation can be in streaks, blotches, or the flower being half one color and half another.   And the plant may produce variegated flowers one month and solid the next.

Many but not all, Four O’Clock flowers have a pleasing fragrance, a mixture of gardenia and orange blossom, on warm evenings.  This, along with a bit of nectar, draws the night flying sphinx moth and other moths to the plants for pollination.  In my garden the white flowered Four O’Clocks seem to be more strongly scented. 

Four O’Clocks were named however, for another flower attribute.  They open up in the evening, about four p.m. in most areas and close by about 11 am.  This isn’t because of light changes, but temperatures falling in the later part of the day.  When it’s cool and cloudy flowers may remain open all day.  And while night flying moths may be the best pollinator hummingbirds and day flying butterflies are also attracted to the flowers when they are open. Four O’Clocks have been used in “floral clocks.”


Other plant parts

The leaves of Four O’Clocks are broad ovals and attached opposite each other on the stem.  Most leaves are a medium green, and somewhat glossy but there are plants with variegated foliage.  Plants are usually well branched and grow about 2 feet high.  They are evergreen in the warmest areas but may die to the ground in other areas.

Four O’Clock plants have black tuberous roots shaped like a thick carrot. In cold winter areas the tubers can be dug and stored inside over the winter.

Four O’Clock flowers produce a single fruit with one black wrinkled seed.  All parts of the plant have some use in either herbal medicine, cosmetics or as dye plants.  There are some edible uses but caution has to be used as too much of the plant can be toxic.  I would list the plant as mildly to very toxic depending on the plant part and how it’s consumed.  It’s not the plant to grow for salad.

Growing Four O’Clocks

I rarely see plants offered in nurseries so most gardeners will generally start them from seed unless you can get some tubers from another gardener.  They grow easily from seed and will flower the same year.  Northern gardeners, (7a and lower), would be better off starting the seed inside about 6 weeks before the last frost and transplanting outside after frost danger has passed.  Because they have a tap root, start seeds individually in paper pots or peats pots so they are easily transplanted. Four O’Clock seed can also be planted directly in the garden where you want it to grow.

Four O’Clocks need full sun, although in very hot climates they will do fairly well in partial shade.  They aren’t fussy about soil.  They can withstand some dry conditions but do better with regular watering.  The plants have very few pests or diseases, aphids are sometimes a problem.  Knock aphids off with a strong stream of water.  Four O’Clocks are seldom touched by deer or rabbits.

In planting zones 7b-8a it might be a good idea to mulch plants heavily in winter.  In zones 7a and lower the plant can be dug after a light frost.  Cut the foliage back to about an inch and let the tubers dry in a warm shady place for a day or two.  Then store in a cool place above freezing packed in wood shavings.  Plant outside in spring after frost danger has passed.



Herbal and other uses of Four O’Clocks

For those who like herbal medicine Four O’Clocks are a gold mine.  I do want to urge caution with using this plant, especially when consuming it, as it can be quite poisonous.  Modern science has confirmed that Mirabilis jalapa does have many medicinal chemicals and many uses for the plant are being explored.

Root extracts of Mirabilis jalapa have antiviral properties and a patent has been awarded for a product that helps control tobacco mosaic virus and other plant viruses. In herbal medicine the powdered root was used on injuries and abscesses.  The powdered root was also baked into cornbread and given to women with menstrual problems.  Powdered root was also considered to be an aphrodisiac.  Root extracts also have antifungal properties.

The roots also have some blood sugar lowering properties and are being studied for use in the treatment of diabetes.

Four O’Clocks have been shown to have pain relieving and antispasmodic properties and was often used for gastrointestinal problems such as colic and diarrhea. Boiled leaves or leaf extracts are used for this and are also used on painful wounds, for sprained or injured muscles and other pain. 

Leaves and stems have anthelmintic (worm killing properties).  Leaf poultices were used to remove freckles and skin spots.  Leaves and roots are also diuretics and emetics.

The flowers of Four O’Clocks are mashed and boiled to make an edible red dye for foods and also to dye cloth.

Plants are used for bioremediation of soils, they take up and store harmful chemicals.  Flowers are used in the production of gold nano particles also.

Here’s a resource for science based information on medicinal qualities.
International Journal of Pharmacological Research


ISSN: 2277-3312 Journal DOI:10.7439/ijpr
IJPR Volume 6 Issue 05 (2016) 160

Caution- only people experienced in herbal medicines should use Four O’Clocks in this way.  Pregnant women should not use it.  Do not eat Four O’Clocks despite some references claiming its edible when boiled.  This has resulted in some serious poisoning cases.

Four O’Clocks are interesting flowers on their own merit and you don’t have to have a medicinal use for them to enjoy them.  Children are often fascinated by the changing flowers. They are an excellent plant for low maintenance and cottage gardens. Try some in your garden.

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