How to Plant and Grow Four O'Clock

Four o'clock has fragrant tubular-shaped flowers that come in various colors and patterns. Sometimes you even get blossoms of different colors on the same plant. These flowers open in the late afternoon, around 4 p.m. (hence the name), and close up again the following morning. Because it loves to self-seed, this classic cottage garden bulb can often be planted once and enjoyed for years. Use four o'clock to fill up space quickly as an annual in a mixed bed, or provide splashes of color in a container. Four o'clock is hardy in warm Zones 8-11.

Four O'Clock is toxic if eaten, so keep away from children and pets.

Where to Plant Four O'Clock

Plant four o'clocks in full sun and well-drained soil. Situate this nighttime bloomer near a bedroom window to enjoy its fragrance during warm evenings. Grow them in containers or gardens, mixing them with other flowering plants.

How and When to Plant Four O'Clock

Four o'clock is extremely easy to start from seeds (it will even self-seed in optimum conditions). Soak them in water overnight before planting to improve their odds of germinating. Plant seeds directly in the 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 transplants, plant them outside after the last frost date.

Four O'Clock Care Tips

It's easy to care for four o'clocks. Regular watering and feeding are all they need, with an occasional pruning.

Light

Plant four o'clock in full sun. Many varieties will tolerate part shade but risk flopping over, thanks to this plant's ultimate large size and fast growth pattern.

Soil and Water

Four o'clocks grow in most soils but prefer well-drained, evenly moist soil with a slightly acidic pH. Water when the top 1 to 2 inches of soil are dry but prevent root rot by avoiding overwatering. Mulch around the plants to keep moisture in the ground. They're somewhat drought-tolerant.

Temperature and Humidity

Warm weather is best for four o'clocks grown as perennials in warmer locations. However, they'll die in the cold winter months when grown as annuals in cooler spots.

Fertilizer

If your soil lacks nutrients, fertilize four o'clocks once a month. When planted in higher-quality soil, fertilizing is needed only once a year.

Pruning

Trim away faded flowers and shoots to keep plants looking healthy when the weather is dry. Pinching back the main root when four o'clock is young will result in a bushier plant.

Potting and Repotting Four O'Clock

Four o'clocks are large plants, so don't do as well in containers as other plants do. Look for smaller varieties if you want to plant them in pots.

Pests and Problems

Part-shade conditions may lead to problems with powdery mildew. Look out for white or brown rust or leaf spot. Use preventive measures to keep fungus from growing, including tossing out affected plants and plant rotation.

How to Propagate Four O'Clock

Although often treated as an annual, four o'clock is a tender perennial that produces tuberous roots. It ultimately flowers better if grown from one of those tubers than from seed. Dig up the roots in the fall after frost has killed back the foliage. Wash the tubers, allow them to dry, and then store them in moist (but not wet) peat moss or sawdust in a cool, dry place until planting time the following spring. This is also the best option for varieties that won't look the same if grown from seeds you save from the plant.

Once the threat of frost has passed, you can plant the overwintered tubers outside again. First, turn the soil about 12 inches deep. Dig a hole 1 inch deeper and two times bigger than the tuber. Place the tuber upright with its roots at the bottom of the hole. Fill the hole with soil, then tamp gently to remove air pockets. Soak with 1 inch of water, and keep the soil moist for about two weeks. Keep them well-hydrated as they grow.

Types of Four O'Clock

'Limelight' Four O'Clock

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

'Red Glow' Four O'Clock

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

Four O'Clock Companion Plants

Cosmos

This cottage-garden favorite fills your garden with color all season. The simple, daisylike flowers appear in cheery shades on tall stems that are great for cutting. The lacy foliage makes a great backdrop for shorter plants, as well. Plant cosmos from seed directly in the ground in spring. Or start from established seedlings. Zones 2-11

Flowering Tobacco

There are several types of nicotiana, also called flowering tobacco because it's a cousin of the regular tobacco plant. Try the shorter, more colorful types in containers or the front of beds or borders. The taller, white-only types, which can reach 5 feet, are dramatic in the back of borders. And they're ideal for night gardens; they're usually most fragrant at dusk. Zones 10-11

Petunia

Petunias are vigorous growers and prolific bloomers from mid spring through late fall. Color choices are nearly limitless, some with beautiful veining. Many are sweetly fragrant. Some also tout themselves as "weatherproof," meaning the flowers don't close up when water splashes them. Wave petunias have made this plant even more popular. Reaching up to 4 feet long, they're great as a groundcover or when cascading from window boxes and pots. Zones 10-11