How to Plant and Grow Four O'Clock Flowers

Four o'clock flowers boast fragrant, tubular-shaped blooms in various colors and patterns—sometimes you even get blossoms of different shades on the same plant. Their most special trait, however, is their daily blooming cycle. In the late afternoon, around 4 p.m. (hence the name), these showy flowers open up. They remain open overnight, but by morning, the colorful blooms appear closed once more.

Four o'clock flowers are a classic cottage garden bulb that usually self-seeds after its initial planting. The evening bloomers are a great choice for quickly filling space in a mixed bed or providing vibrant splashes of color in a container.

Where to Plant Four O'Clock Flowers

Four o'clock flowers, hardy in Zones 8-11, thrive in full sun and well-drained soil. Situate this nighttime bloomer near a front porch, deck, or bedroom window to enjoy its fragrance during warm evenings. Mix four o’clock flowers with other blooming plants to bring an old-fashioned cottage garden look to any bed or border that receives ample sunlight and offers space for the plants to spread.

Additionally, some varieties of four o'clock flowers can be grown as a ground cover in warm climates. When grown in this fashion, the plant can be mowed to ground level at the end of the season in October.

How and When to Plant Four O'Clock Flowers

Four o'clock flowers are extremely easy to start from seeds, and the plant will even self-seed in optimal conditions. Before planting, soak seeds in water overnight to improve their odds of germinating. Plant the seeds directly in garden soil after the last frost date, or start plants indoors 6 to 8 weeks ahead of that date. If you prefer to work with seedlings or dormant tubers, plant them outside after the last frost date.

If you are sowing seeds directly into the ground, place them 6 inches apart and cover with a half-inch of soil. When seedlings emerge, thin them to about 12 to 18 inches apart. Transplanted seedlings should also be planted 12 to 18 inches apart to allow for growth.

When planting a dormant tuber, dig a hole twice the size of the tuber and place the tuber in the hole with its pointed end down. Holding it in place, cover your tuber with 1 to 2 inches of soil, tamping it down as you work. Space multiple tubers about 24 inches apart and water them thoroughly when you are finished planting.

Four O'Clock Flowers Care Tips

Little hands-on maintenance is required to care for four o'clock flowers. Regular watering and feeding is all they need, with an occasional pruning.

Light

Plant four o'clock flowers in full sun. Many varieties will tolerate part shade but risk flopping over because of the plant's large size and fast growth pattern.

Soil and Water

Four o'clock flowers grow in most soils but prefer well-drained, evenly moist soil with a slightly acidic pH. Plants will need water when the top 1 to 2 inches of soil is dry. Add a layer of mulch around four o'clock flowers to keep moisture in the ground, and avoid overwatering, as this will cause root rot. Once established, four o'clock flowers are somewhat drought-tolerant.

Temperature and Humidity

Four o’clock flowers are tender perennials, so they do not tolerate temperatures below 30°F. In warmer climates, however, the tubers can be overwintered in the ground for fresh growth the following spring. Four o’clock flowers are not fussy about air humidity.

Fertilizer

If your soil lacks nutrients, fertilize four o'clock flowers monthly during the growing season. Follow product label directions for the proper amount to use. When planted in higher-quality soil, fertilizing is necessary only once a year.

Pruning

Trim away faded flowers and shoots to keep four o'clock flowers looking healthy when the weather is dry. When the plant is young, you can encourage bushier growth by pinching off the main stem of your four o'clock flowers. Pinch as close to the leaf nodes as possible without damaging the buds underneath. This will ideally result in the plant sending out multiple new stems from the pinch point.

Potting and Repotting Four O'Clock Flowers

Four o'clock flowers are large plants, so they don't do as well in containers as other plants. Look for smaller varieties if you want to plant the perennial in pots.

Overwintering

In mild climates where winter temperatures do not dip below 30°F, four o’clock flowers can be overwintered in the ground. Water the soil deeply in the fall, trim the plant back to 3 or 4 inches, and cover with 4 to 5 inches of dry organic mulch.

If you wish to bring back your four o’clock flowers the following spring in cooler climates, you will need to overwinter them by digging up the tuberous roots in the fall. Wearing gloves, use a garden fork to pull up the tubers. Rinse them off then place them in a shady spot for about a week to dry out. Store your tubers in a container filled with peat moss or sawdust, and place the container in a dry location where the temperature will stay between 35°F-45°F. You can replant your dormant tubers once the danger of frost has passed in the spring.

Pests and Problems

If four o'clock flowers are planted in part-shade conditions, powdery mildew may occur. You'll also want to look out for white or brown rust, as well as leaf spot. Use preventive measures to keep fungus from growing, including plant rotation and tossing out affected plants.

How to Propagate Four O'Clock Flowers

There are two ways to propagate four o’clock flowers from seed. You can allow the plants to reseed themselves and thin them out when seedlings emerge, or you can collect four o’clock seeds by plucking the dark, pea-sized seeds from fading blooms. Remember to use caution when handling the seeds, as they contain toxic compounds. Dry your saved seeds in a cool location for several days and then place them in an envelope. Keep your packet of seeds in a cool, dry place until the following spring.

In spring—about 6 to 8 weeks before the last frost—soak your seeds overnight in a bowl of water. Prepare a tray or some grow pots with moist potting mix and sow the seeds about 1/4 inch deep. Position the pots in a warm spot (about 70°F) that gets at least 6 hours of sunlight each day, and keep the soil evenly moist. Do not allow the soil to completely dry out. Once seedlings emerge, they should be hardened off for a week before they are transplanted outdoors.

Since four o'clock flowers are a tender perennial that produces tuberous roots, the plant can also be divided. Look for bulbous growth buds (or eyes) that branch from the original stem. Cut the tuber apart with a sharp straight-edged knife (not a serrated one). Each division needs a section of the original stem and an eye for successful division. Replant your divided tubers immediately to avoid shocking the plant.

Types of Four O'Clock Flowers

'Limelight' Four O'Clock Flowers

Mirabilis 'Limelight' bears chartreuse foliage and bright magenta flowers on 2-foot-tall plants.

'Red Glow' Four O'Clock Flowers

This selection of Mirabilis bears vibrant red flowers on 2-foot-tall plants.

Four O'Clock Flowers Companion Plants

Cosmos

Cosmos, a cottage garden favorite, fills your garden with color all season. The simple, daisy-like flowers appear in cheery shades on tall stems that are great for cutting, and the plant's lacy foliage makes a dynamic backdrop for shorter plants. Plant cosmos from seed directly in the ground in spring or start from established seedlings. Cosmos plants are hardy in Zones 2-11.

Flowering Tobacco

There are several types of nicotiana, more commonly known as flowering tobacco. A cousin of the regular tobacco plant, this fragrant bloomer is hardy in Zones 10-11. Try the shorter, more colorful types of flowering tobacco in containers or at the front of beds or borders. The taller, white-only types, which can reach 5 feet, add drama to the back of borders. Any variety is ideal for night gardens as they're usually most fragrant at dusk.

Petunia

Petunias are vigorous growers and prolific bloomers from mid-spring through late fall. Color choices are nearly limitless—some have beautiful veining in the blooms, and many are sweetly fragrant. Some petunia varieties also tout themselves as "weatherproof," meaning the flowers don't close up when water splashes them. Zones 10-11 are ideal for petunia planting.

Garden Plans for Four O'Clock Flowers

Moon Garden

There's no rule that says gardens are purely for daytime enjoyment. This garden plan, filled with night bloomers such as moonflower, four o'clock flowers, and angel's trumpet, is at its best when the moon is high in the sky. Be sure to include a garden bench—you'll want to be able to take in the sweet fragrances (which attract nighttime pollinators like fireflies) while sitting in the moonlight.