Ornamental · Nyctaginaceae
Four O'clock
Mirabilis jalapa
Tuck a few seeds in once and four o'clock rewards you with fragrant evening flowers all summer, then quietly sows the next year for you.
Full sun
Every 3–7 days
50–86°F · 10–30°C
60–80 days
Overview
Four o'clock earns its name by coming alive at the end of the day, and that quiet habit makes it a joy to grow. The trumpet-shaped flowers stay closed through the heat and open in the late afternoon, filling the evening air with a sweet scent that draws in moths and hummingbirds. Best of all, a single bushy plant can carry blooms in several colors at once, sometimes even striped or splashed across the very same flower.
You'll find it grows fast and forgiving, climbing to 1.5 to 4 feet (46 to 122 cm) in a single season. Most gardeners treat it as a tender perennial grown as an annual, since it dies back with hard frost but tucks its energy away in fleshy, tuberous roots. Lift those roots before winter and you can welcome the same plant back year after year, which feels like a small reward for a little care.
The one thing to keep in mind is how eagerly it spreads. Four o'clock drops a generous load of seed and reseeds itself freely, a gift in a relaxed border and a bit of tidying in a neat bed. The seeds and roots are also toxic, so it helps to know where it likes to self-sow before you settle it near pets or children, and then you can enjoy it with an easy mind.
Care
The short version: four o'clock asks for little, so give it full sun, steady moisture in well-drained soil, and a light monthly feed. Pinch it while young to keep it full, and if volunteers worry you, just snip the spent flowers before the seeds drop.
Light
Four o'clock is happiest and blooms most freely in full sun, where it stays nicely compact. It will gladly take partial shade and still flower for you, though a shadier corner can coax the stems to stretch and lean, so sunnier is the kinder choice.
Water
Aim to keep the soil evenly moist right through the season, and a little extra attention helps during summer heat. It loves humus-rich ground that drains well and won't mind the occasional wet spell, but try not to leave it sitting in soggy soil for long.
Soil
Give it well-drained, humus-rich loam if you can, though honestly four o'clock makes do with almost any soil you offer. A pH anywhere from 6.0 to 7.5 keeps it content, so most ordinary garden beds will do the job without any fuss on your part.
Temperature
Warmth is what it craves, roughly 50°F to 86°F (10°C to 30°C), and you'll see it take off once the heat settles in. Frost does end the top growth, which is simply why so many gardeners grow it as an annual in cooler spots, and that's perfectly fine.
Humidity
There's nothing to fuss over here, since ordinary outdoor humidity is all it asks. What helps far more is good spacing and airflow, because crowded plants tend to flop and hold dampness around the stems, so a little breathing room goes a long way.
Feeding
A balanced general-purpose fertilizer about once a month through the growing season keeps the flowers coming. A gentle hand is best, since too much feed, especially nitrogen, encourages weak, leggy stems that lean and snap, and easing back spares you that worry.
Pruning
Happily, four o'clock needs very little pruning, though a simple pinch when it's young rewards you with a fuller, sturdier plant, and trimming any leggy stems tidies things up. Clearing away spent plants before the seeds drop is the easiest way to keep its self-sowing gently in check.
Size & spacing
Plants grow 1.5 to 4 feet (46 to 122 cm) tall and spread 12 to 24 inches (30 to 61 cm) across. Give each one that full bit of room so the branching stems can settle in and air can move around them, and you'll have healthier plants for it.
When to plant
Four o'clock simply loves warmth, and the one thing it won't forgive is frost, so timing is the easy part. Start a few seeds indoors in late winter, or wait and sow them right into warm ground once frost has passed. Either way works, and your plants will bloom from midsummer until the first hard cold of fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6 to 8 weeks before the last spring frost; soak seeds overnight to speed germination
- Plant: After all danger of frost has passed, about the same time as tomatoes
- Harvest: Summer through fall; flowers open in late afternoon or early evening and wilt by the following morning
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Take heart, because four o'clock is a wonderfully forgiving plant, and almost everything that puzzles a grower comes from its own enthusiasm rather than pests or disease. You might meet soft stems that lean, a happy crowd of self-sown seedlings, or seeds that take their time. Find your situation below and you'll see the fix is gentle and well within reach.
Seeds that sit and refuse to sprout
If your seeds are taking their time, the hard seed coat is almost always the reason, since it slows how quickly water can soak in, and cool soil only stretches the wait. Give them a friendly head start by soaking them overnight or nicking the coat before sowing. Tuck them about 1/4 inch deep, keep the soil near 68°F to 70°F (20°C to 21°C), and you'll see them break ground in 5 to 7 days.
Fix:
- Soak seeds in water overnight or nick the seed coat before sowing
- Sow 1/4 inch deep and keep soil at about 68 to 70°F
Weak, brittle stems that flop over and snap
Don't be discouraged if the stems lean, because four o'clock simply makes a lot of soft, branching growth in a hurry, and it can't always hold itself up. A little too much nitrogen or a crowded spot tends to make things worse, so the plant tips over and the stems snap near the base. The remedy is easy: pinch young plants for a bushier, sturdier shape, leave each one room to breathe, and slip in a stake for the tall ones if they still want to sprawl.
Fix:
- Provide stakes or grow among supporting companions
- Pinch young plants to promote a bushier, sturdier habit
- Avoid over-fertilizing with high-nitrogen feeds
Volunteer seedlings popping up everywhere the next year
A single plant scatters a generous load of seed, and that vigorous self-seeding can turn last year's flower bed into this year's crop of cheerful volunteers. The fix is gentle, so deadhead the spent blooms before the seed sets, and lift the young seedlings while they come up easily. In colder areas you have an even simpler option: dig and store the tuberous roots over winter and skip the reseeding altogether.
Fix:
- Deadhead spent flowers before seeds form
- Remove volunteer seedlings while young
- Dig and store tuberous roots over winter rather than allowing reseeding
Toxicity
This one comes with a kind word of caution alongside its beauty. The seeds and roots are toxic to cats, dogs, horses, rabbits, livestock, and birds, and they aren't safe for people either, bringing on stomach pain, nausea, vomiting, and diarrhea if eaten. The seeds are the riskiest part, and the roots can leave sensitive skin irritated, so choose a spot where curious pets and small children can't reach the seedpods and you can relax.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
A cat that chews the seeds, roots, or foliage tends to drool, lose interest in food, and vomit. The seeds are the part most likely to cause trouble, so it helps to simply keep them out of reach.
Dogs Toxic
Dogs respond much the same way, with drooling, an upset stomach, and diarrhea after eating any part of the plant. Curious chewers that dig up and gnaw the roots are the ones most at risk, so a watchful eye helps.
Horses Toxic
The alkaloids in the seeds and roots can leave a horse drooling and colicky, with diarrhea soon after. Keeping the plant well clear of paddocks and turnout takes the worry out of it.
Rabbits Toxic
Rabbits should never nibble four o'clock, since the same toxins bring on a sore, upset gut. It's an easy thing to remember: never toss trimmings into a hutch or run.
Livestock Toxic
Grazing animals such as goats, sheep, and cattle can suffer stomach pain and diarrhea if they reach the foliage or dig up the roots. Fencing the plant off from pasture keeps everyone safe.
Birds Toxic
For birds, the seeds are the most dangerous part, and a single pecked seed or chewed leaf can cause vomiting and lasting gut upset. The kindest approach is to treat the whole plant as off-limits.
People Caution
The seeds and roots are toxic if eaten and cause stomach pain, nausea, vomiting, and diarrhea, so keep them away from small children who might mistake a seed for a treat. Handling the roots can also leave sensitive skin red and irritated, so just pop on gloves when you dig them and you'll be fine.
Keep seeds and roots away from pets and children; wear gloves if you are sensitive when digging or handling tuberous roots.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Most four o'clocks are sold simply by color, which makes shopping easy, but a handful of named selections are lovely to hunt down for their special flowers or foliage.
'Broken Colors'
Every flower comes striped and splashed with contrasting colors, so a single plant gives you blooms where no two look quite the same.
'Limelight'
Bright chartreuse leaves play beautifully against neon pink flowers, making a pairing you can spot from clear across the garden.
'Marbles' series
A cheerful mixed strain of bicolor blooms streaked and splotched in shifting color pairings all across the planting.
How to propagate
Good news for a first try: four o'clock is one of the most forgiving plants to multiply. You can sow seed for a quick first-year show, or hold on to a plant you love by lifting its roots before winter.
SeedEasy
Sow indoors 6 to 8 weeks before last frost or direct sow outdoors after frost danger passes · Germinates in about 5 to 7 days at 68 to 70°F; blooms the first season
Seed is the easiest way to begin, and the lovely part is that your plants flower their very first summer. Soak the seeds overnight or nick the hard coat, sow them about 1/4 inch deep, and space the seedlings 12 to 24 inches apart. Start them indoors 6 to 8 weeks before your last frost, or sow straight into warm ground once frost has passed, and they'll sprout in about 5 to 7 days at 68°F to 70°F (20°C to 21°C).
DivisionModerate
Lift and divide tuberous roots in fall for winter storage, replanting in spring after frost · Stored tubers resprout in spring once replanted in warm soil
Where winters turn cold, you can carry a favorite plant safely over by its roots, much as you would a dahlia. Dig the tuberous roots in fall before the first frost, shake off the soil, and tuck them somewhere cool, dry, and frost-free. Replant them in spring once the soil warms, and they'll happily resprout for another season.
Myths
Four o'clock is edible or harmless because it is such a common garden flower.
It's an easy thing to assume, but being common doesn't make it safe. The seeds and roots are toxic if eaten and bring on stomach pain, nausea, vomiting, and diarrhea, and the roots can leave sensitive skin irritated. Keep the seeds away from children and pets, and slip on gloves when you handle the roots, and you'll have nothing to worry about.
The flowers always open right at four o'clock.
It's a charming idea, but the clock really has nothing to do with it. The blooms open in the late afternoon or early evening, cued by fading light rather than a fixed hour, and they gently wilt away by the next morning. On cool, overcast days you may even see them open a touch earlier, which is a lovely little surprise.