How to Grow Four O’Clock (Mirabilis jalapa) from Seed: A Complete Guide

Four o’clock has one of the most fitting names in the plant kingdom. Its trumpet-shaped flowers open in late afternoon — typically between 4 and 6 PM — and remain open through the night, filling the garden with a sweet, jasmine-like fragrance that is most pronounced in the evening hours. By morning, the flowers have closed, often wilting as the sun rises, giving the plant its curious daily rhythm of show and hide.

This tropical American native has been a garden favorite for centuries, valued as much for its ease of cultivation as for its reliable evening fragrance. The plant produces tubers that grow larger and more productive each year, and established four o’clock clumps can survive decades with minimal care — delivering hundreds of flowers nightly from spring through autumn.

At JC Garden Seed, four o’clock seeds are a consistent bestseller, particularly among gardeners who want color and fragrance in their evening garden spaces. The plant is also a fascinating one to grow with children, who delight in watching the flowers open and close on a daily schedule that seems almost mechanical in its reliability.

Understanding Four O’Clock

Mirabilis jalapa is the species most commonly grown in gardens. Despite its common name and its appearance, four o’clock is not related to the true lily family — it belongs to the Nyctaginaceae family, which includes the ornamental bougainvillea.

Plant Characteristics

Four o’clock is a bushy, spreading herbaceous perennial in frost-free climates, growing 60 to 100 cm tall and wide. In areas with frost, it behaves as a tender perennial — the top growth dies back in winter but the tuberous roots resprout in spring.

The leaves are ovate to lance-shaped, dark green, and have a slightly sticky texture. The flowers — the real attraction — are trumpet-shaped with five flared petals, produced in clusters at the stem tips and leaf axils.

Flower Colors

Four o’clock flowers come in an extraordinary range of colors, often with bicolor and tricolor patterns on the same plant. The classic color range includes:
– Deep magenta pink
– Bright yellow
– Pure white
– Coral orange
– Vibrant red

A single four o’clock plant frequently produces flowers in different colors — sometimes on different branches, sometimes with striped, mottled, or bicolor flowers on the same plant. This variability is a natural characteristic of M. jalapa and makes each plant a pleasant surprise.

The “Limelight” variety produces chartreuse-yellow foliage with magenta flowers — a striking combination that extends the plant’s ornamental interest beyond the flowers.

Flowering Behavior

Flowers open in late afternoon and remain open through the night. The fragrance is sweet and heavy, most pronounced between dusk and midnight. The flowers attract night-pollinating moths, which are the primary pollinators of this species.

In the morning, flowers close or wilt rapidly. In cool weather, flowers may remain open longer into the morning. On cloudy days, flowers may open earlier or stay open longer.

The Tuber System

One of the most remarkable characteristics of four o’clock is its tuberous root system. After the first growing season, the plant develops a large, carrot-shaped tuber that stores energy and allows the plant to resprout vigorously year after year. In established plants, the tuber can weigh several kilograms and the plant can produce 50 to 100 flowers per day during peak season.

Climate and Growing Conditions

Four o’clock is native to tropical and subtropical regions of the Americas. It thrives in warm conditions and is more tolerant of heat and drought than many other flowering plants.

Temperature Requirements

Germination and growth are optimal between 20°C and 30°C. Four o’clock tolerates heat well — mature plants continue flowering even in temperatures above 35°C. The tuberous roots are frost-susceptible — in areas with light frost, the top growth dies back but roots survive underground.

In tropical lowland gardens, four o’clock grows year-round and can become quite large and productive over time. In subtropical areas with cold winters, treat it as a tender perennial or grow it as an annual from seed each spring.

Light Requirements

Full sun to partial shade. Four o’clock blooms best with at least 6 hours of direct sunlight. In very hot tropical climates, some afternoon shade helps flowers last longer by reducing heat stress.

In heavy shade, four o’clock becomes leggy, produces fewer flowers, and may not flower at all.

Soil Preparation

Four o’clock is not fussy about soil. It grows in average garden soil, poor soil, and even container growing medium. The main requirement is good drainage — waterlogged soil causes tuber rot.

Soil Requirements

Average to poor, well-draining soil is ideal. Four o’clock tolerates poor, rocky, or sandy soils that would challenge many other flowering plants. Do not add compost or organic matter to the planting hole — this creates overly rich conditions that produce lush foliage at the expense of flowers.

pH range: 5.5 to 7.5 is acceptable.

Container Growing

Four o’clock grows well in large containers (at least 30 cm in diameter). Use quality potting mix with good drainage. Container plants may need more frequent watering than those in the ground, and the tuber system means containers should be large enough to accommodate the expanding root system over time.

Sowing Four O’clock Seeds

Four o’clock seeds are large, easy to handle, and have a distinctive appearance — round, dark, textured seeds with a hard outer coat. One gram contains approximately 8 to 12 seeds.

Seed Characteristics

The seeds look like small, dark nuts with a knobbly surface. They have a hard outer shell that contributes to their long storage life (seeds remain viable for 3 to 5 years with proper storage).

The hard seed coat benefits from soaking before planting to speed up germination. Soak seeds in warm water for 12 to 24 hours before sowing.

Sowing Indoors

In short-season climates or for earliest blooms, start four o’clock seeds indoors 6 to 8 weeks before the last expected frost. Use individual pots (peat pots work well to avoid transplant shock) filled with seed-starting mix.

Sow seeds 1.5 to 2 cm deep. Maintain temperatures of 21 to 24°C. Germination takes 7 to 14 days.

Transplant carefully into the garden after all danger of frost has passed — four o’clock seedlings develop a taproot quickly and do not tolerate root disturbance well. Peat pots allow planting without disturbing roots.

Direct Sowing

In warm climates and tropical regions, direct sowing is simple and effective. Sow seeds 1.5 to 2 cm deep in well-prepared soil. Space seeds 30 to 45 cm apart.

Water thoroughly after sowing and keep the soil moist until seedlings emerge (7 to 14 days).

Spacing

Plants should be spaced 30 to 45 cm apart in the garden. Each plant will grow into a substantial bush 60 to 100 cm tall and wide within a single season.

Watering

Four o’clock is notably drought-tolerant once established. The tuberous root system stores water and allows the plant to survive dry periods that would kill many other flowering plants.

Watering Schedule

During seedling establishment, water every 2 to 3 days. Once established (after 4 to 6 weeks), four o’clock needs water only during extended dry periods — typically once a week in most tropical climates.

In containers, check soil moisture every 2 to 3 days during hot weather. Container plants may need more frequent watering.

Signs of Water Stress

Drought-stressed four o’clock wilts dramatically but recovers quickly after watering. The main effect of water stress is reduced flower production. Consistent watering keeps plants blooming heavily.

Overwatering

Too much water produces lush foliage but few flowers. Four o’clock is one of those plants that actually benefits from slightly lean conditions. In rich soil with frequent watering, it becomes bushy and green but disappoints in the flower department.

Fertilizing

Four o’clock does not require feeding in average soil. In fact, over-fertilizing is a common cause of poor flowering — the plant grows lush foliage at the expense of blooms.

If your soil is genuinely poor (sandy, rocky, or heavily depleted), apply a light dose of balanced fertilizer (10-10-10) once at the beginning of the growing season. One application is usually sufficient.

Growing and Maintenance

Four o’clock is a low-maintenance plant once established. The main tasks are occasional watering during dry periods and cleanup of dead top growth at the end of the season.

Staking

Mature four o’clock plants can become top-heavy with flowers and may lean or fall over, especially in wind. If this is a problem, stake individual stems with bamboo rods or grow plants against a support structure.

Overwintering Tubers

In areas with frost, allow the top growth to die back naturally after the first frost. The tuberous roots can be left in the ground and will resprout in spring. Alternatively, dig up the tubers, allow them to dry for a few days, store in barely damp sand or peat moss in a cool, frost-free location, and replant in spring.

In tropical gardens, four o’clock grows as an evergreen perennial and does not need any winter protection.

Common Pests and Problems

Four o’clock is remarkably pest-resistant. The slightly sticky foliage is naturally resistant to many insects, and the plant’s vigor means it usually outpaces any minor pest problems.

Occasional Aphids

Aphids may cluster on young shoots in spring, but four o’clock’s natural vigor and slightly sticky foliage usually keeps aphid populations in check without intervention.

Slugs

Young seedlings may be nibbled by slugs. Control with iron phosphate bait or beer traps if needed.

Leaf Spot

Brown spots on leaves, usually caused by fungal infection in humid conditions. Usually not severe enough to require treatment — just remove affected leaves if they bother you.

Root Rot

Caused by waterlogged soil. Prevention: ensure good drainage and avoid overwatering.

Landscape Uses

Evening Garden

Four o’clock is the classic plant for the evening garden — position it near windows, outdoor seating areas, or garden paths where its evening fragrance can be appreciated. Plant it where the flowers receive afternoon sun but the planting area is visible from your evening sitting spot.

Night-Scented Garden

Four o’clock pairs well with other night-scented plants like moonflower (Ipomoea alba), night-blooming jasmine (Cestrum nocturnum), and tuberose for a garden that comes alive after dark.

Mixed Borders

The bushy, substantial form of four o’clock makes it useful in mixed borders and as a backdrop for lower-growing plants. Its dark green foliage provides a good background for showier flowers in front.

Container Growing

Four o’clock grows well in large containers and provides a showy, fragrant display on patios and decks. Use a container at least 40 cm in diameter.

Seed Saving

Four o’clock produces large, showy seed pods after flowering. Allow the seed pods to dry on the plant — they turn brown and papery when mature. Collect seeds and store in paper envelopes in a cool, dry location.

Seeds remain viable for 3 to 5 years with proper storage. Four o’clock comes true from seed — saved seeds produce plants identical to the parent (unlike hybrid varieties that do not).

Frequently Asked Questions

Q1: Why are my four o’clock flowers not opening?

A1: Four o’clock flowers naturally open in late afternoon (around 4 to 6 PM). If you are checking in the morning or early afternoon, the flowers may simply not be open yet. If flowers fail to open at all during the day, it may be too cool (below 15°C) or too shady — ensure full sun and warm temperatures.

Q2: Can four o’clock grow in shade?

A2: Four o’clock tolerates light shade but blooms best in full sun with at least 6 hours of direct sunlight. In heavy shade, plants become leggy, produce few or no flowers, and may not develop the large tuberous root system that makes them long-lived.

Q3: Why do different flowers on the same plant have different colors?

A3: This is a natural characteristic of Mirabilis jalapa. The genes for flower color are expressed differently in different flowers on the same plant, and the color can even vary from flower to flower on the same branch. This is not a problem — it is one of the charming quirks of four o’clock.

Q4: Are four o’clock flowers fragrant?

A4: Yes. Four o’clock has a sweet, jasmine-like fragrance that is most pronounced in the evening and night. The fragrance attracts night-pollinating moths. If you want to maximize fragrance, plant four o’clock near seating areas or windows.

Q5: Can I grow four o’clock in containers?

A5: Yes. Use a container at least 40 cm in diameter to accommodate the tuberous root system. Ensure good drainage, use quality potting mix, and water regularly during hot weather. Container four o’clock may need staking to prevent toppling.

Q6: Is four o’clock invasive?

A6: In some tropical regions, four o’clock has naturalized and can spread from seed. The plant is not considered seriously invasive, but if self-seeding is a concern in your area, remove spent flower heads before they set seed. The plant’s tendency to self-sow is usually welcomed rather than problematic in most gardens.

—

Related Articles

– How to Grow Morning Glory from Seed: Complete Guide for Tropical Gardens
– How to Grow Marigold from Seed: Complete Guide for Home Gardeners
– How to Grow Cosmos from Seed: Complete Guide for Gardeners