Ornamental · Nyctaginaceae
Four O'clock
Mirabilis jalapa
Sow it once and watch four o'clock fire off fragrant evening flowers all summer, then reseed itself for an encore next year.
Full sun
Every 3–7 days
50–86°F · 10–30°C
60–80 days
Overview
Four o'clock lives up to its name by springing to life as the day winds down. The trumpet-shaped flowers hold tight through the heat, then burst open in the late afternoon and pour a sweet scent into the evening that reels in moths and hummingbirds. The real kicker is that one bushy plant can throw blooms in several colors at once, sometimes striped or splashed across the very same flower.
It grows fast and grows easy, rocketing to 1.5 to 4 feet (46 to 122 cm) in a single season. Gardeners run it as a tender perennial grown as an annual in most spots, since hard frost takes the top while the plant stashes energy in fleshy, tuberous roots. Lift those roots before winter and the same plant comes roaring back year after year.
The flip side of all that energy is its drive to spread. Four o'clock drops a heavy load of seed and reseeds itself freely, a bonus in a wild border and a job in a tidy bed. The seeds and roots are toxic too, so scout where it likes to self-sow before you plant it near pets or children.
Care
The short version: four o'clock thrives in full sun with steady moisture in well-drained soil and a light monthly feed. Pinch it young for a bushy plant, and deadhead before the seeds drop if you want to rein in the volunteers.
Light
Four o'clock really gets going in full sun, where it stays compact and blooms hard. It will take partial shade and still perform, but a shadier spot pushes the stems to stretch and flop, so chase the sun for the best show.
Water
Keep the soil evenly moist all season and step it up in summer heat. It loves humus-rich ground that drains well and brushes off the odd wet spell, but it will not stand sitting in soggy soil for long.
Soil
Plant it in well-drained, humus-rich loam, though four o'clock takes on just about any soil you throw at it. Hold a pH of 6.0 to 7.5 and most garden beds suit it without any fuss.
Temperature
It revels in warmth, roughly 50°F to 86°F (10°C to 30°C), and takes off the moment the heat arrives. Frost wipes out the top growth, which is why cooler regions run it as an annual.
Humidity
No humidity target to chase, since average outdoor air is plenty. Put your energy into good spacing and airflow, because crowded plants flop and trap dampness around the stems.
Feeding
A balanced general-purpose fertilizer about once a month through the growing season keeps the flowers coming. Go light though, because too much feed, especially nitrogen, pumps out weak, leggy stems that lean and snap.
Pruning
Four o'clock barely needs pruning, but a quick pinch when young builds a fuller, sturdier plant, and snipping leggy stems sharpens it up. Pull spent plants before the seeds drop to keep its self-sowing from running away.
Size & spacing
Plants shoot to 1.5 to 4 feet (46 to 122 cm) tall and spread 12 to 24 inches (30 to 61 cm) wide. Give each one that full spacing so the branching stems have room to stretch and air moves freely.
When to plant
Four o'clock chases warmth and bolts at the first frost, so let the heat lead. Kick the seeds off indoors in late winter, or sow them straight into warm ground once frost clears out. Do that and the plants pump out flowers from midsummer right to 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
Here is the great part: four o'clock practically runs itself, and the few quirks that show up come from sheer growing energy rather than pests or disease. Three things crop up the most, namely soft stems that lean, a burst of self-sown seedlings, and seeds that take their time. Spot yours below and the fix takes almost no effort.
Seeds that sit and refuse to sprout
Blame the hard seed coat, which throttles how fast water gets in, and cold soil only drags out the wait. Fire them up by soaking them overnight or nicking the coat before sowing. Tuck them about 1/4 inch deep, hold the soil near 68°F to 70°F (20°C to 21°C), and they punch through 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
Four o'clock cranks out soft, branching growth in a hurry, and the stems cannot always keep pace, so the plant starts to lean. Pile on nitrogen or crowd it and the trouble grows, until stems snap clean near the base. Pinch young plants for a bushier, sturdier shape, give each one elbow room, and stake the tall ones if they still 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
One plant scatters a heavy load of seed, so that vigorous self-seeding turns last year's flower bed into this year's army of volunteers. Get ahead of it by deadheading the spent blooms before the seed sets, and yank young seedlings while they pull up easy. In colder areas, 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
Worth growing, worth respecting. The seeds and roots are toxic to cats, dogs, horses, rabbits, livestock, and birds, and they hit people too, sparking stomach pain, nausea, vomiting, and diarrhea if eaten. The seeds pack the biggest punch, and handling the roots can irritate sensitive skin, so plant it where pets and small children cannot reach the seedpods and grow on with confidence.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
A cat that chews the seeds, roots, or foliage tends to drool, go off its food, and vomit. The seeds cause the most trouble, so keep them well out of reach.
Dogs Toxic
Dogs go the same route, drooling, with an upset stomach and diarrhea after eating any part of the plant. The curious chewers that dig up and gnaw the roots run the biggest risk.
Horses Toxic
In horses the alkaloids in the seeds and roots can bring on drooling and colic, with diarrhea hot on its heels. Keep the plant well clear of paddocks and turnout.
Rabbits Toxic
Rabbits should never nibble four o'clock, since the same toxins fire up a sore, upset gut. Never pitch trimmings into a hutch or run.
Livestock Toxic
Grazing animals such as goats, sheep, and cattle can land in stomach pain and diarrhea if they hit the foliage or dig up the roots. Fence the plant off from pasture.
Birds Toxic
For birds the seeds are the most dangerous part, and a pecked seed or chewed leaf can spark vomiting and lasting gut upset. Treat the whole plant as off-limits.
People Caution
For people 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 glove up when you dig them.
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 come labeled by color, but a few standout selections reward anyone who hunts them down for their flowers or foliage.
'Broken Colors'
Every flower rolls out striped and splashed with contrasting colors, so a single plant carries blooms where no two match.
'Limelight'
Bright chartreuse leaves crank up neon pink flowers into a combination you read from across the garden.
'Marbles' series
A mixed strain of bicolor blooms streaked and splotched in shifting color pairings right across the planting.
How to propagate
Multiplying four o'clock is a thrill, because it could hardly be easier. Sow seed for a fast first-year show, or carry a favorite plant forward 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 fast lane, and the 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. Launch them indoors 6 to 8 weeks before your last frost, or sow straight into warm ground once frost clears, and they 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 bite, carry a favorite plant forward by its roots, the way you would a dahlia. Dig the tuberous roots in fall before the first frost, knock off the soil, and stash them somewhere cool, dry, and frost-free. Replant them in spring once the soil warms and they spring back for another season.
Myths
Four o'clock is edible or harmless because it is such a common garden flower.
Common does not equal safe, plain and simple. The seeds and roots are toxic if eaten and trigger stomach pain, nausea, vomiting, and diarrhea, and the roots can leave sensitive skin irritated. Keep the seeds away from children and pets, and wear gloves when you handle the roots.
The flowers always open right at four o'clock.
Forget the clock, it has nothing to say here. The blooms open in the late afternoon or early evening, cued by fading light rather than a fixed hour, then wilt away by the next morning. Cool, overcast days can coax them open earlier still.