Ornamental · Nyctaginaceae
Four O'clock
Mirabilis jalapa
Pop it in once and four o'clock keeps its fragrant evening flowers coming all summer, then sows itself for next year.
Full sun
Every 3–7 days
50–86°F · 10–30°C
60–80 days
Overview
Four o'clock gets its name because it really does wake up at the end of the day. The trumpet-shaped flowers stay shut through all that heat, then open in the late afternoon and fill the evening with a sweet scent that brings in moths and hummingbirds. And here's the fun part: one bushy plant can show off blooms in several colors at once, sometimes even striped or splashed on the very same flower.
It grows fast and it's easy to please, hitting 1.5 to 4 feet (46 to 122 cm) in just one season. Most folks treat it as a tender perennial they run as an annual, since it dies back with hard frost but tucks away energy in fleshy, tuberous roots. Lift those roots before winter and you can bring the same plant back year after year, which is a nice trick.
The catch? It loves to spread. Four o'clock drops a heavy load of seed and reseeds itself freely, which is great in a wild border but a bit of a chore in a tidy bed. The seeds and roots are toxic too, so it pays to know where it likes to self-sow before you tuck it in near pets or kids.
Care
The short version: four o'clock wants full sun, steady moisture in well-drained soil, and a light feed once a month. Pinch it while it's young so it stays bushy, and if you'd rather skip the volunteers, just deadhead before the seeds fall.
Light
Four o'clock blooms its best in full sun, where it stays nice and compact. It'll handle partial shade and still do okay, but a shadier spot tends to make the stems stretch out and flop, so why not give it the sun?
Water
Keep the soil evenly moist through the season, and lean in a little more during summer heat. It likes humus-rich ground that drains well and won't mind the occasional wet spell, but it really doesn't want to sit in soggy soil for long.
Soil
Go for well-drained, humus-rich loam if you can, though honestly four o'clock isn't picky and takes just about any soil. A pH somewhere between 6.0 to 7.5 keeps it happy, so most garden beds work just fine.
Temperature
It loves it warm, roughly 50°F to 86°F (10°C to 30°C), and really gets going once the heat shows up. Frost kills the top growth outright, which is why folks in cooler spots just grow it as an annual.
Humidity
No numbers to chase here, since average outdoor humidity is all it wants. What matters more is 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 blooms coming. Easy does it though, because too much feed, especially nitrogen, gives you weak, leggy stems that lean and snap.
Pruning
Four o'clock barely needs pruning, but a quick pinch when it's young makes for a fuller, sturdier plant, and trimming leggy stems tidies it up. Want to keep the self-sowing down? Pull the spent plants before the seeds drop.
Size & spacing
Plants get 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 bit of room so the branching stems have space and air can move through.
When to plant
Here's the thing about four o'clock: it's all about warmth and won't put up with frost. So either start seeds indoors in late winter or sow them straight into warm ground after the last frost. Do that and you'll get flowers from midsummer right up 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
Good news, because four o'clock is pretty laid-back, and most hiccups come from how vigorously it grows rather than any pest or disease. What usually trips people up? Floppy stems, a swarm of self-sown seedlings, and seeds that take their sweet time. Find what matches below and the fix is usually no big deal.
Seeds that sit and refuse to sprout
If your seeds are dragging their feet, it's usually that hard seed coat, which slows down how fast water gets in, and cold soil only makes the wait longer. Give them a head start by soaking them overnight or nicking the coat before sowing. Pop them about 1/4 inch deep, keep the soil near 68°F to 70°F (20°C to 21°C), and they'll 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
Four o'clock piles on soft, branching growth in a hurry, and the stems can't always keep up, so they start to lean. Too much nitrogen or a crowded spot makes it worse, and that's when the plant tips and the stems snap near the base. The fix is easy enough: pinch young plants for a bushier, sturdier shape, give each one 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 drops a ton of seed, so all that vigorous self-seeding turns last year's flower bed into this year's crop of volunteers. Want to stay ahead of it? Deadhead the spent blooms before the seed sets, and pull the young seedlings while they're still easy to lift. And in colder areas you can just 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
There's a catch worth knowing about. The seeds and roots are toxic to cats, dogs, horses, rabbits, livestock, and birds, and they're not safe for people either, since eating them brings on stomach pain, nausea, vomiting, and diarrhea. The seeds are the riskiest bit, and handling the roots can bother sensitive skin, so plant it somewhere pets and little kids can't get at the seedpods.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
A cat that chews the seeds, roots, or foliage usually drools, goes off its food, and throws up. The seeds are the part most likely to cause trouble, so it's worth keeping them out of reach.
Dogs Toxic
Dogs react pretty much the same way, with drooling, an upset stomach, and diarrhea after eating any part of the plant. The curious chewers that dig up and gnaw the roots are the ones most at risk.
Horses Toxic
In horses, the alkaloids in the seeds and roots can bring on drooling and colic, with diarrhea following close behind. Best to keep the plant well clear of paddocks and turnout.
Rabbits Toxic
Rabbits shouldn't ever nibble four o'clock, since the same toxins bring on a sore, upset gut. Whatever you do, don't toss trimmings into a hutch or run.
Livestock Toxic
Grazing animals like goats, sheep, and cattle can wind up with stomach pain and diarrhea if they get into the foliage or dig up the roots. Fence the plant off from pasture and you're good.
Birds Toxic
For birds the seeds are the most dangerous part, and just one pecked seed or chewed leaf can cause 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 leave sensitive skin red and irritated too, so wear gloves 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 just get sold by their color, but a few named ones are worth hunting down for their flowers or foliage.
'Broken Colors'
Every flower turns up striped and splashed with contrasting colors, so a single plant carries blooms where no two look quite the same.
'Limelight'
Bright chartreuse leaves play off neon pink flowers for a combo you can spot from clear across the garden.
'Marbles' series
A mixed strain of bicolor blooms streaked and splotched in color pairings that keep changing across the planting.
How to propagate
Want more four o'clocks? It's about as easy as plants get. Grow it from seed for a quick first-year show, or hang on to one 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 easy way in, and the best part is your plants flower their very first summer. Soak the seeds overnight or nick that 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's 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 get cold, you can carry a favorite plant over by its roots, kind of like a dahlia. Dig the tuberous roots in fall before the first frost, shake off the soil, and stash them somewhere cool, dry, and frost-free. Replant them in spring once the soil warms up, and they'll resprout for another season.
Myths
Four o'clock is edible or harmless because it is such a common garden flower.
Easy to think, 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 wear gloves when you handle the roots.
The flowers always open right at four o'clock.
Cute idea, but the clock's got 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 wilt away by the next morning. On a cool, overcast day? They might even open a little earlier.