Can a flowering plant tell time? When I first started gardening, I was surprised to find out that there is a plant with flowers that open in the late afternoon.
When the day starts to cool down, and the bees, butterflies, and hummingbirds make one last pass before the night moths take over, four o’clock flowers open and release their inviting fragrance. This makes them perfect for planting near your patio and in containers on porches and decks. Their fragrance scents the air while you sit and enjoy the cool of the evening.
This tender perennial is a cottage garden favorite. It hits all the right notes – fragrant, self-sowing, and easy-care. Your grandma or great-grandma probably grew them, but they have fallen out of favor in the last several decades.
But they are so easy to grow, so adaptable, and bloom so profusely it’s time to invite them back into our 21st-century flower gardens.
Four o’ clocks are bushy annuals with vibrant flowers that also appropriately goes by the name of “the Marvel of Peru”. They oftentimes have a sweet citrus-like fragrance.
The plant grows 1-2 feet wide and 2-3 feet tall, resembling a small shrub. It quickly becomes covered with an ever-blooming multitude of trumpet-shaped flowers in various colors. The flowers can be white, pink, red, yellow, purple, or magenta and are often spotted or variegated. Sometimes a plant will start blooming in one color and then offer flowers in another color!
The blooms are non-stop through the growing season. Each flower opens in the late afternoon (earlier on cloudy days), blooms all night, and then dies in the morning. But four o’clock are such prolific bloomers, you won’t notice the end of each individual flower.
Types of Four O’Clocks
Mirabilis jalapa is the most commonly grown variety. These plants are native to tropical South America and are in the family Nyctaginaceae. With its five lobed sepals, the flower bears a strong resemblance to nicotiana, hibiscus, and petunia.
Other plants in the Nyctaginaceae family include:
- Mirabilis multiflora, a wildflower found in Colorado, Utah, New Mexico, Nevada, Arizona, western Texas, and southern California.
- Mirabilis longiflora, native to Arizona, Texas, and northern Mexico.
- Bougainvillea and abronia (aka sand verbena or wild lantana).
Where to Plant Four O’Clocks
This plant is perennial in USDA zones 7 through 11. In colder zones, they are grown as an annual. They die at first frost. But they reseed freely, and you can also lift the tubers and store them for the winter.
They prefer 6 to 8 hours of sunlight (full sun) but will tolerate a little bit of shade.
They prefer acidic soil but are adaptable. They grow best in poor, nutrient-deficient, well-draining soil. Consistently soggy soil will result in root rot. That being said, they still do like moisture.
Caring for Four O’Clocks
Four o’clocks need regular watering. Provide an inch of water weekly, either from rainfall or your garden hose in droughty times.
Because these plants bloom so profusely, you might think they are heavy feeders requiring frequent fertilization. But they will do just fine without any fertilizer at all. You can apply a slow-release balanced fertilizer in the spring, but it isn’t necessary.
Deadheading and Pruning
With so many flowers being produced daily, deadheading is an impossible task. Removing the spent flowers will not encourage the plant to produce more. They will keep blooming regardless of whether you prune or not.
Nonetheless, in the middle of summer, four o’clocks can start to look a bit bedraggled if you are not deadheading. Cut the plant back by a third to invite a fresh flush of growth and new flowers!
Insects and Diseases
Not much troubles four o’clocks. Aphids and Japanese beetles might be a problem. Fungal diseases such as fusarium, rust, and cercospora can develop if the foliage does not dry quickly after watering. Root rot can occur if the soil is kept too wet.
Caution: Plant is Toxic to People and Pets
All parts of these plants are toxic to people and pets and cause vomiting and diarrhea if eaten. Some people may experience itching or a rash from the sap.
Growing Four O’Clocks from Seed
Four O’Clocks’ seeds are bigger than a pea and easy to harvest. Harvest them when they turn black, then store them in a paper envelope until next spring. Storing the seeds in plastic could invite mold and rot.
When you are ready to plant, soak the seeds overnight. Alternatively, you can scarify them with a nick from a knife or a rub of sandpaper. You want to break the physical barrier the seed coat provides. That allows moisture in, which aids in germination.
Plant the seeds outdoors after the danger of frost has passed. Turn over and fluff up the soil to about a foot down. By doing this, you give the developing tuberous roots an easy path.
Smooth the soil and dig a small hole. Plant the seeds ¼ inch deep. Space the seeds about 1 foot apart. Cover and firm the soil gently, and then water the seeds in.
Keep the soil moist until the seeds germinate, which usually takes about 10 days. Monitor the soil moisture carefully – don’t let the seedlings dry out. In 6-10 weeks your four o’clock plants will start producing flowers.
You can also start seeds indoors 6 to 8 weeks before the last frost date in your area. This can give you a head start on flowering. Transplant your baby four o’clock plants into the garden after the danger of frost has passed.
These plants reseed freely, so you may never have to plant them again! If they start to take over your garden, pull out the rogue seedlings as they come up. They can be invasive in certain areas, so check with your county extension service to be sure.
Lifting and Storing Four O’Clock Plants
If you live in a USDA hardiness zone lower than zone 7, you can lift the tubers and store them through the winter. You want a spot that stays dry and cool but not freezing, like a basement, a crawl space, or a root cellar that stays about 50°F (10°C).
Make sure to dig out the tubers before the first frost. Frost will kill the plant.
Be prepared for some heavy lifting. Four o’clocks can develop massive taproots over time that can weigh up to 40 pounds! Don’t worry, they won’t get that big in one season, but they will still be bigger than you might expect. Gently dig up the plants and shake off all the dirt. Allow them to dry. Do not wash them as this encourages rot.
Store them in a cardboard box in layers of dry newspaper. Try not to have the tubers touch each other and poke a few holes in the box for ventilation.
After the danger of frost has passed in the spring, you can replant the tubers. Dig holes twice as wide as the tubers and one inch deeper. The growing tip needs to be 1 inch deep in the soil. Water the tubers in, and keep the soil slightly moist until stems start growing.
After that, four o’clocks will need about 1 inch of water per week.
Designing with Four O’Clocks
These plants are perfect for people who are at work all day and only have the evenings to enjoy their gardens. Plant them around the patio, porch, or deck, either in the ground or containers.
Make a Clock Garden with morning glories, daylilies, four o’clocks, and moonflowers.
Four o’clocks are excellent plants for a well-draining rain garden. Their large taproots are really good at soaking up excess rainwater.