Did you know there’s a plant named after a time of day?
And while you may recall the rather old-fashioned four o’clock (Mirabilis jalapa) from visits to Grandma’s house, the name of the plant isn’t a reflection of when our older relatives often tend to eat dinner.
Instead, the name indicates the time of day when the plant’s trumpet-shaped flowers open.
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The flowers bloom in late afternoon in response to a temperature drop. Nocturnal moths and other nighttime pollinators are attracted to their nectar.
They remain open throughout the night and into the morning when temperatures rise and the flowers wilt. Like daylilies, four o’clock flowers bloom just a single time, then fade and eventually fall off the plant.
On cloudy days, the flowers open earlier and sometimes won’t close at all. Again, this is not due to a lack of light, but rather, to temperatures that are lower than usual.
Many gardeners find deadheading unnecessary because even the wilted blooms are attractive, and this plant blooms profusely with or without deadheading.
Whether you’re drawn by nostalgia or you’re looking for an appealing, colorful, easy-care perennial for a cottage garden, border, or container, you’ll want to check out this old-fashioned favorite.
Here’s what to expect in this guide:
What You’ll Learn
What Are Four O’Clock Flowers?
Tender perennials in Zones 7b to 11b, gardeners in other Zones often grow these beauties as annuals. They will self-sow.
This bushy nocturne usually grows one to four feet tall, and one to three feet wide, but perennial plants have been known to reach six feet in height in ideal conditions.
It is heat- and drought-tolerant, and a favorite of hummingbirds, bees, butterflies, and other pollinators.
Wild critters know not to ingest the roots and seeds of this plant, because they are poisonous.
If your pooch has a propensity for eating random yard objects, you may want to collect the dark, leathery, round seeds immediately after they make a showing, or skip growing this old-fashioned ornamental altogether.
In the deep south, M. jalapa begins blooming in late spring, while northern gardeners will have to wait until midsummer to catch a whiff of the highly fragrant blooms.
Cultivation and History
As if “four o’clock” weren’t an interesting enough name, this plant also goes by “marvel of Peru,” a nod to its native tropical South American habitat.
This flower has been cultivated for hundreds of years.
Indigenous people used the roots for medicine and as a hallucinogen, and Europeans found the plants in the Americas and brought them back to their countries around 1540.
In those days, the red flowers were used to make food coloring.
In its heyday a couple of generations ago, this was a popular “pass-along” plant in the southern US, meaning neighbors and friends frequently shared the plant with each other to grow in their own gardens.
Four o’clocks grow easily from seed, and it’s not that tough to grow them from tubers uprooted at season’s end, wintered over, and planted out again the following spring.
Here’s the go-to info for either approach:
One huge advantage of four o’clocks is that even beginners can succeed at growing them from seed.
And you can collect the heirloom seeds at season’s end to share or start more plants.
In areas with a shorter growing season, you may want to start four o’clocks indoors six to eight weeks ahead of your area’s average last frost date.
Fill trays or small pots with seed-starting mix. If you wish you can opt to soak the seeds overnight in warm water to speed up sprouting.
The seeds need light to germinate, so space them a few inches apart and merely press them into the soil about a quarter-inch.
Place the container in a room with temperatures between 65 and 75°F, and where it will receive light either from a window or a grow light.
Keep the soil moist with a clean spray bottle of water. You can expect the seeds to germinate within about 15 days.
Once they’re a couple of inches tall and have at least two sets of true leaves, transplant the seedlings to two-inch cells or into the container where you plan to grow them for the season.
Seedlings can go in the garden when they’re about six weeks old, after you’ve gradually conditioned them to the increased light and warmth of the great outdoors.
Harden them off when conditions permit for about an hour on the first day, adding an hour each day for about a week.
Gently remove them from their pots or seed-starting cells, and plant them to the same depth as in their containers. Provide plenty of water as they get acclimated.
To direct sow in the garden, space the seeds about 12 inches apart, covering them with a quarter-inch of fine soil and keeping them moist until they germinate.
To share tubers with a friend or save them at season’s end to plant out next year, dig them up with a gardening fork or spade, being careful to unearth the entire tuber to avoid accidentally injuring it or slicing off a portion.
Then use your shovel or your hands to gently remove the clumps from the garden, much as you would when lifting dahlias.
Shake the soil from the tubers and store them somewhere cool and dry – but not freezing – like an unheated garage.
Good air circulation is important – some gardeners will layer them between sheets of newspaper in an open crate or box with holes punched in it.
The following year, plant them after the last frost.
Space them one or two feet apart and plant them deep enough to cover with the root end pointed down and the crown end where new growth will emerge planted just below the soil surface.
How to Grow
You may have heard dramatic stories about four o’clocks growing in extra-poor soil or surviving a months-long drought. And indeed, they are tough and tolerant.
But instead of relying on this survival instinct, to grow the healthiest four o’clocks with the most blooms, plant them in well-draining soil that’s been amended with aged compost or other organic material.
Grow them in full sun or an area that receives morning sun and afternoon shade.
If you’re growing them in containers, plant four in a pot 20 inches in diameter that can hold at least five gallons of growing medium.
Be sure to water the plants during dry spells if you want them to look fabulous, versus just getting by.
Aim for about an inch of supplemental water every couple of weeks if your area is experiencing periods of high heat or zero rainfall.
As for fertilizer, these plants can do without it.
But they’ll flourish and bloom with abandon if you give them an all-purpose balanced fertilizer in early spring and at least once midway through the growing season, or once a month if your soil is lacking in fertility.
- Plant either in full sun or a spot with morning sun and afternoon shade.
- To keep the plants looking fresh, provide about an inch of supplemental water every few weeks during summer’s dry heat.
- Fertilize to encourage flowering.
Pruning and Maintenance
Those growing four o’clocks from seed can pinch back the main stem when immature seedlings are about five or six inches tall. This will encourage sturdier plants that bloom profusely.
Also make sure to pick off any seeds that you don’t want to self-sow, or pull up the new seedlings before they get a stronghold in the garden or other areas where you don’t want them to grow.
For anyone lucky enough to have the opportunity to grow four o’clocks as perennials, there are a couple of additional seasonal chores you’ll need to take on.
Ahead of cooler temperatures each year, make sure to clip any dead or damaged foliage.
Add a two-inch layer of mulch around the stems to help the plants retain moisture through their dormant period.
Be sure to opt for a pollinator-friendly mulch, one that hasn’t been treated with pesticides, like dry shredded leaves from your own garden or untreated pine straw.
Cultivars to Select
If color is your thing, you’ve come to the right place.
Four o’clock flowers can be pink, red, magenta, lavender, yellow, or white.
The flowers may be a solid hue, or they may have more than one color in a striped, splotchy, or spotted pattern.
You may even see different combinations of shades and patterns on a single plant.
And to further brighten your days, the flowers of some varieties will change color as the plant matures.
So, you buy a lovely yellow plant at the garden store in May, and walk out one July evening – around the time when Grandma’s cooking dinner – to discover you now have a plant with dark pink flowers!
You may want to purchase seeds in a particular shade or see if you can’t scare up some starts from neighbors or a local gardening club.
There are also seeds available from reputable vendors online. Few will have a specific cultivar name, usually being tagged just as “four o’clocks,” perhaps with a color named afterward.
For example, you can find red-flowering seeds available from Eden Brothers and yellow-flowering ones available at Outsidepride via Amazon.
If you’d like to mix it up, a collection of bicolor, red, magenta, white, and yellow marvel of Peru seeds are sold in 25-seed packets from Botanical Interests.
As for more specific cultivars, consider these:
A Burpee-bred mixture, these four o’clocks are all bicolored or multicolored and dramatic, some of them with deep orange and apricot blooms, others a creamy white with magenta highlights, and still others in light pink and bright white with light orange portions.
These are a natural choice for tropical plantings or splashy container ornamentals for the porch or gazebo.
Kaleidoscope Mix is available in 45-seed packets from Burpee.
This option sports striped, one-and-a-half-inch flowers that are pink, rose, red, and yellow, all in a marbled pattern. The scent is delicate and redolent of orange blossom.
Marbles Mix is available in 35-seed packets from Burpee.
Managing Pests and Disease
One of the reasons these colorful plants are so appealing is that they are resistant to deer marauders, and aren’t bothered much by other pests or diseases.
There are a few potential foes to watch for though, including these:
As mentioned above, critters seem to know not to eat these plants, though you may want to watch out for your dogs if they’re inclined to munch whatever is in their path.
About the only insect that might attack is the aphid, an unappealing little sap-sucker that’s oval in shape and may appear in any number of colors, including buff, brown, or green.
You can blast aphids with a steady stream of water, or follow some of the other strategies outlined in our guide.
Should you spot leaves that look like they’ve been chewed on and you can peer right through the damage, you may be battling slugs.
Another indicator is the pleasant slime trails they leave behind… Just kidding, they’re gross!
A top strategy for keeping slugs at bay involves diatomaceous earth – read more about it in our guide to keeping slugs and snails under control.
Again, these are tough plants. But they’re not impervious to these potential plant diseases:
A soil-borne fungus can cause Fusarium wilt, putting four o’clocks in a bad way.
You might notice they’re drooping, a symptom that’s usually followed by yellowing leaves.
Unfortunately, ornamentals that are suffering from fusarium wilt can’t stage a comeback. Instead, you’ll need to pull up all the affected plants, taproots and all, and send them to the trash bin, not the compost.
Then make sure to move any healthy plants to a new spot for next year, following the instructions for overwintering tubers outlined in the Propagation section above.
If you see small, yellow, halo-shaped spots on the leaves, your plants may have leaf blight. Ack!
These spots start small but they can turn brown and cause the leaves to wither pretty quickly.
About the only way to treat this ailment is to eradicate all of the affected plants.
If you notice reddish-brown spots on the foliage or stalks, your plants might have rust.
If you determine that’s the condition, work quickly to remove the affected leaves and stems, then treat the remainder of the plant with neem oil.
Try this product from Bonide, available from Arbico Organics.
Since these are such charming plants to share with beginner gardeners and those who are nostalgic for simpler times, it’s handy that the seeds are so simple to save.
After some of the flowers have faded, you will want to start collecting the seeds they produce before they get dispersed onto any available soil, where they’ll sprout next spring.
Look for the small, dark, football-shaped seeds to appear at the tip of the stems after the dead flowers drop.These are actually fruits, which hold the seeds inside.
Pick them directly from the plants, and don’t forget to look for extras that have already fallen to the ground.
Place them on a piece of brown paper or cardboard, and set it out of the light in a cool spot where air circulates freely.
Let the seeds dry completely before you store them. That usually takes about a week, and you’ll know they’re dry when the surfaces are so hard you can’t puncture them with your thumbnail.
For long-term storage, move the dried seeds to small envelopes or little glass jars with screw-on lids. Be sure to label the containers with the plant’s name and the date when you harvested seed.
Move those containers somewhere dry and dark for the duration, until you’re ready to take them out again for gifting or sowing.
Along with being a lovely reminder of simpler times in the past, four o’clocks can hold their own with the most colorful ornamental bedding plants of today.
Planted close together, they form an attractive annual hedge that butterflies and hummingbirds will home in on.
They also grow well in containers on the patio or a garden wall, as long as you’re willing to offer up a bit of extra supplemental watering throughout the driest portions of the summer.
Their old-fashioned appeal plays well in a cottage garden, but the colors and drought-tolerance also make them suitable for tropical plantings. For the latter, grow them in front of taller tropicals like elephant’s ear.
Perhaps the best use of M. jalapa is as a pretty flower to share with beginner gardeners.
It’s a snap to save seeds or lift tubers, and neighbors, grandkids, and the local seed library could all enjoy the nostalgic beauty of this pretty perennial.
Quick Reference Growing Guide
|Plant Type:||Tender perennial flower often grown as annual||Flower/Foliage Color:||Bicolor, magenta, pink, variegated, white, yellow/green|
|Native to:||Tropical South America||Tolerance:||Deer, drought, heat, poor soil|
|Hardiness (USDA Zones):||7b-11b||Soil Type:||Organically rich, fertile|
|Bloom Time/Season:||Late spring, summer, early autumn||Soil pH:||6.0-7.0|
|Exposure:||Full sun; morning sun and afternoon shade||Soil Drainage:||Well-draining|
|Spacing:||12-24 inches||Attracts:||Bees, butterflies, hummingbirds, moths, other pollinators|
|Planting Depth:||1/4 inch (seeds), crown end at soil surface (tubers)||Companion Planting:||Other drought-tolerant plants like black-eyed Susan, lantana, garden phlox|
|Height:||18-36 inches, up to 6 feet in ideal conditions||Uses:||Borders, containers, cottage garden, pollinator garden, tropical landscape|
|Water Needs:||Low to average||Family:||Nyctaginaceae|
|Common Pests and Diseases:||Aphids, slugs; fusarium wilt, leaf blight, rust||Species:||Jalapa|
A Time-Honored Flower Tradition
There’s never a bad time to plant these colorful beauties.
Order seeds or ask a neighbor for a “pass-along,” and help to revive a plant from an earlier time that surely deserves a comeback.
Do you remember four o’clocks from your childhood? Do you have some growing in your garden now? Tell us your tales of this well-loved antique in the comments section below.
And if you’re planning to incorporate more old-fashioned ornamentals into your garden or landscape, read these flower guides next: