How to Grow Four O’Clocks: Fragrant Mirabilis Jalapa Blooms That Open at 4 PM Every Day
Four o’clocks open at 4 PM every day, right when you get home. Complete guide: seed starting, zone care, overwintering, and evening placement tips.
Most summer flowers have already peaked by the time you pull into the driveway. Zinnias and marigolds hit their stride at noon; by late afternoon they’re wilting under the heat. Four o’clocks do the opposite. Right around 4 PM — sometimes earlier on cloudy days — their trumpet-shaped blooms open and the fragrance starts building, reaching its peak just as the evening cools.
If you work during the day, this plant was practically designed for you. A single established clump produces dozens of blooms per evening, in colors from crimson to bright yellow to pure white — sometimes all three on the same plant. Mirabilis jalapa (also called Marvel of Peru) is one of the few garden plants where the best show starts right when you get home.
Why Four O’Clocks Open at 4 PM
The name isn’t poetic — it’s accurate. Mirabilis jalapa flowers open in response to a drop in temperature and light intensity that typically occurs between 4 and 8 PM. Once open, they stay that way for 16 to 20 hours, wilting the following morning as the air warms again.
This timing is an evolutionary adaptation, not a coincidence. The tubular, trumpet-shaped flowers and the sweet, tobacco-like evening fragrance evolved specifically to attract hawkmoths (family Sphingidae) — nocturnal pollinators with the long tongues needed to reach nectar deep in the flower tube. Bees and butterflies can visit too, but the plant synced its entire bloom schedule to the hawkmoth’s activity window. The fragrance intensifies as temperatures fall, which is the plant’s mechanism for signaling to its target pollinator.
This biology has a practical implication for garden placement. Position four o’clocks where you actually spend time in the evenings — beside a patio seating area, along an evening walkway, or beneath a window you open in summer. Within 6–8 feet, the fragrance is unmissable. Beyond that, it fades quickly.
Native to dry tropical regions of South America — Mexico, Peru, and Guatemala — four o’clocks arrived in Europe by 1525 and were cultivated by the Aztecs for both ornamental and medicinal purposes. They naturalized through much of the warm world and became so beloved in southern US gardens that generations shared seeds between neighbors, a tradition that continues today.
Starting from Seed
Four o’clocks are easy to grow from seed, but timing is critical if you want blooms before late summer.
Indoor start (recommended for zones 3–7): Start seeds indoors 6–8 weeks before your last frost date. Before sowing, nick each seed lightly with sandpaper or soak them overnight in water — this breaks seed coat dormancy and significantly speeds germination. Press seeds ¼ inch deep into damp seed-starting mix. At 68–70°F, seedlings typically appear within 5–7 days, according to University of Wisconsin Extension. For zone-specific start dates, see our guide on when to start seeds indoors.
Direct sow: In zones 7 and warmer, direct sow after the last frost once soil temperatures reach 65°F. Direct-sown plants bloom 10–12 weeks from sowing, compared to 8–10 weeks from transplants.
Transplanting: Move seedlings outdoors only after all frost risk has passed — about the same time you’d plant tomatoes. Space plants 12–24 inches apart; they fill in quickly once established.
Pinching: When seedlings reach 5–6 inches tall, pinch the main growing tip. This encourages branching and produces a bushier plant with significantly more flower stems — a step that noticeably increases bloom density and one most growing guides skip.
Soil, Light, and Planting Site
Four o’clocks thrive in full sun — at least 6 hours of direct sun daily. They’ll tolerate partial shade but produce fewer flowers. In very hot climates (zones 8 and above), afternoon shade protects against heat stress while morning sun still drives strong growth.
Soil adaptability is one of their strengths. They’ll grow in almost any type, performing best in humus-rich, well-drained ground at a neutral to slightly acidic pH (6.0–7.0). Sandy or clay soils can be improved with compost at planting, but these plants rarely sulk about imperfect conditions.
Evening placement strategy: Unlike daytime bloomers that look good from a distance, four o’clocks need to be close enough to smell. Position them within 6–8 feet of wherever you spend your evenings — a deck, a pergola seating area, or the steps outside your back door. A planting along the path you walk from the car is ideal: every day greets you with fragrance the moment you arrive.
Container growing: Four o’clocks perform well in containers with a minimum 5-gallon pot per plant. The container advantage is flexibility — you can move the pot to exactly where you sit each evening. Use a well-draining potting mix and check soil moisture daily in hot weather, as containers dry faster than in-ground soil. Our container gardening guide covers potting mix options and drainage tips.
Water and Fertilizer
Once established, four o’clocks are drought-tolerant — the tuberous root system stores water efficiently. During the first few weeks after transplanting, water regularly to help the root system establish. After that, about 1 inch of supplemental water every 2–3 weeks during dry spells is sufficient in most climates.
The fleshy tuberous roots are susceptible to rot in consistently waterlogged soil. If plants are yellowing or wilting despite adequate moisture, ease back on watering and let the soil dry between cycles before resuming.
For fertilizer, apply a balanced all-purpose formula (such as 10-10-10) at transplanting and again at midsummer. Avoid high-nitrogen options — excess nitrogen pushes leafy growth at the expense of blooms. Lush, deep-green plants with few flowers are the classic sign of over-fertilizing with nitrogen.
Seasonal Care Calendar
| Month | Task |
|---|---|
| March–April | Start seeds indoors 6–8 weeks before last frost; soak or nick seeds before sowing |
| May | Transplant after last frost; direct sow in warm climates; pinch seedlings at 5–6 inches |
| June–September | Peak bloom period; deadhead to extend the season; water during dry spells |
| October | Allow seed set if you want self-sowing; dig tubers before hard frost in zones 6 and colder |
| November–March | Store tubers in a cool dry location; leave in ground with mulch in zones 7–11 |
Deadheading isn’t essential — four o’clocks bloom whether or not you remove spent flowers — but it tidies the plant and can extend the season. Stop deadheading in September if you want seeds for self-sowing next year. Our guide on deadheading flowers covers the basic technique.
Overwintering by USDA Zone
Whether four o’clocks survive winter depends entirely on your USDA zone, and the strategy changes significantly between zone groups.
Zones 9–11: Four o’clocks are perennial. Plants die back in late fall and re-sprout from the root system each spring with no intervention. In the warmest zones, they self-seed so vigorously they can become weedy — UF/IFAS notes they spread aggressively in Florida’s warmest regions. Remove unwanted seedlings while small.
Zones 7–8: Tubers often survive mild winters with protection. After the first frost kills the foliage, cut stems back and cover the root zone with 4–6 inches of mulch or straw. Zone 7 isn’t reliable — an unusually cold winter can kill in-ground tubers — so keep some saved seeds as backup.
Zones 3–6: Treat as annuals, or dig and store tubers. Established tubers are often carrot-sized or larger after one season and produce much more vigorous plants the following year than seeds started from scratch.
How to store tubers in zones 3–6:
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→ View My Garden Calendar- After the first frost kills the foliage, cut plants back and dig carefully — tubers can go surprisingly deep.
- Brush off loose soil; do not wash them, as moisture during storage causes rot.
- Allow tubers to dry for about three weeks in a warm room, turning every few days for even moisture loss.
- Place in a cardboard box with holes punched for airflow. Arrange tubers so they aren’t touching, separated by layers of newspaper.
- Store in a cool, dry, non-freezing location — a basement corner or above-freezing garage both work well.
- Replant after your last frost date the following spring.
The process is nearly identical to storing dahlia tubers. Our guide to planting spring bulbs and tubers covers related overwinter techniques for other tender perennials.
Cultivars Worth Growing
The species form is worth growing on its own, but several cultivars offer specific advantages:
| Cultivar | Flower Character | Best For |
|---|---|---|
| ‘Jingles’ | Mixed colors on the same plant, classic cottage display | Passalong plant tradition, cottage gardens |
| ‘Broken Colors’ | Streaked and marbled blooms; each flower unique | Close-up planting, talking-point border |
| ‘Limelight’ | Chartreuse/golden foliage that sets off any bloom color | Foliage contrast in mixed borders |
| ‘Marbles’ series | Compact habit reaching about 18 inches | Containers, small patios, front borders |
| ‘Salmon Sunset’ | Warm coral-pink tones | Warm-palette borders with orange or red companions |
A note on color unpredictability: four o’clocks are a classic genetics teaching example. Cross a pink-flowered plant with a white one and the offspring show light pink — a demonstration of incomplete dominance where neither color allele fully overrides the other. A single plant from a mixed-color seed packet can produce several different flower colors, and individual blooms are sometimes streaked with two colors on the same petal. You can’t fully predict what you’ll get, which is part of what makes these plants interesting to grow season after season.
Toxicity — What You Need to Know
Four o’clocks are not safe to eat. Both the roots and seeds contain alkaloids that cause stomach pain, nausea, vomiting, and diarrhea if ingested, according to NC State Extension. The seeds are the main concern — they resemble small, dark peppercorns — so keep them out of reach of children and pets. Handling the roots can cause contact dermatitis in sensitive individuals; wear gloves when digging tubers at the end of the season.
The flowers themselves are low risk to touch. Toxicity is real but not extreme — most accidental ingestions result in GI upset rather than serious harm — but site these plants away from children’s play areas and pet runs as a precaution.
Frequently Asked Questions
How long do four o’clocks take to bloom from seed?
Expect flowers about 8–10 weeks from transplanting indoor-started seedlings, or 10–12 weeks from direct sowing. Starting seeds indoors 6–8 weeks before your last frost date gives you the earliest blooms and the longest season.
Will four o’clocks come back every year?
In zones 9–11, yes — they’re perennial and re-sprout from roots each spring. In zones 7–8, they sometimes survive with heavy mulch but it’s not reliable. In zones 3–6, they won’t survive winter unless you dig and store the tubers before the first hard frost.
Why aren’t my four o’clocks fragrant?
Fragrance isn’t guaranteed — University of Wisconsin Extension notes that plants sometimes lack a noticeable scent even within fragrant-marketed varieties. Fragrance is strongest when temperatures drop in the evening and most noticeable on still, warm summer nights. Plants in full sun tend to produce more fragrance than those in shade.
Do four o’clocks attract hummingbirds?
Yes. Hummingbirds visit the tubular flowers along with hawkmoths, butterflies, and other long-tongued pollinators. Red and pink varieties are especially attractive to hummingbirds.
Can four o’clocks grow in pots?
Yes — use a minimum 5-gallon container with good drainage holes. They make excellent patio plants because you can position them exactly where you sit in the evenings. Our list of top plants for containers includes other fragrant options that pair well with four o’clocks.
Sources
- University of Wisconsin Extension — Four O’Clocks, Mirabilis jalapa. hort.extension.wisc.edu
- NC State Extension Gardener Plant Toolbox — Mirabilis jalapa. plants.ces.ncsu.edu
- UF/IFAS Gardening Solutions — Four O’Clocks. gardeningsolutions.ifas.ufl.edu
- Wikipedia — Mirabilis jalapa
- Gardening Know How — Winterizing Four O’Clocks
