How to Overwinter An Old-Fashioned Favorite: Four o’Clocks

Caleb Melchior is a landscape architect based in the Southeast and a contributing editor to Horticulture. This article runs in the September/October 2017 issue of Horticulture magazine, and appears here with added tips on how to overwinter four o’clocks in colder zones.

Four o’clocks (Mirabilis jalapa) are native to the tropical regions of South America, generating the archaic name “marvel of Peru.” Such an old-fashioned circusy name doesn’t seem fully appropriate for such an elegant plant. Bright green, heart-shape leaves clothe mounds of juicy green stems. As summer heats up, the pillows of foliage swell with tens, then hundreds, of bright-colored buds. When happy hour comes into view, those fat buds swirl open into flat-faced trumpet flowers. Hummingbirds, insects and human garden visitors will zip right over to the golden, apricot and bright pink blossoms.    

overwinter four o'clocks

‘Broken Colors’ is a four o’clock variety bearing patterned flowers that can be various shades.

Four o’clocks aren’t just easy to enjoy. They’re easy to grow, too. Four o’clocks have large seeds, bigger than garden peas. They’re easy to direct-sow. Wait to plant them until after the soil has warmed in spring and danger of frost is past. Soak them overnight and then tuck them in between your early summer plants. As the season heats up and your spring garden plants fade, the four o’clocks will come into their own. (The seeds can also be started in pots in a cold frame or on a warm windowsill if you want a head start on four o’clock season.) Keep a gentle eye on the seedlings. Their large leaves are obvious and easy to distinguish amidst the finer foliage of brachyscome and osteospermum and other late-spring delights.

GROWING NEEDS FOR FOUR O’CLOCKS

Four o’clocks thrive in partial shade in the South, full sun in the North and gloomier climates. Frequent moisture (a good soaking two or three times a week) and well-composted soil will result in the most heavily blooming plants. Check with your local extension before planting four o’clocks, as they can self-sow to the point of invasiveness in some (mostly tropical) regions.

As with any plant that’s easy to grow from seed, four o’clocks come in an astonishing array of different color selections. ‘Broken Colors’ is probably the most common, with seedlings bearing flecked flowers of magenta, white, orange and gold. Single-color strains are available as well. ‘Salmon Sunset’, ‘Yellow’, ‘Bright Orange’, ‘Pink’ and ‘White’ are easy to find if you’re looking to plant a large bank of one-hue four o’clocks  ‘Limelight’ is special; not only does it have brilliant magenta flowers, but also thrilling chartreuse foliage. Or, if you’re feeling indecisive, go harvest seed from plants growing in an alley in your town. Just hold your phone close and watch out for Rottweilers.

6 TIPS ON HOW TO OVERWINTER FOUR O’CLOCKS

overwinter four o'clocks

Mirabilis jalapa (Marvel of Peru, Four o’clock flower), are flowers that open in late afternoon.

For USDA Zones 6 and north follow these tips to overwinter your four o’clocks.

  1. After the plant has died down in late fall, dig the tubers.
  2. Brush soil from the tubers but do not wash them; you want them as dry as possible.
  3. Place the tubers in a cool and dry place, in a single layer (not stacked on each other) for approximately 3-4 weeks, allowing them to dry completely. You may turn them a couple times a week to assure even drying.
  4. Once completely dry, line a cardboard box with newspaper or brown paper bags and place the tubers in the box. It’s best to leave breathing room around the tubers (which look like dark carrots) though it is ok to stack a couple layers, placing paper between the layers.
  5. Cut a few holes in the box to allow air to circulate and to deter rotting.
  6. Store your box(es) in a cool (not freezing), dry location until after the first spring frost and then re-plant them.

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