A few years ago my family visited Monticello in the summer. I was struck by how large Thomas Jefferson’s four o’ clocks (Mirabilis jalapa) were compared to mine. I also liked the fact that it was a plant he grew and wrote about in his journal. These heirloom flowers are still grown today.
Although I had a few small plants in dry, lean soil in full sun, I was inspired to start new plants from seed. I planted them in very rich soil, in an area of the garden that received morning sun and afternoon shade. They thrived and grew to be about 2 feet tall with light green leaves and many yellow or pink blossoms.
Although they are named for opening at 4:00 pm, mine never do. The blossoms are sensitive to light and temperature and prefer to open when the evening cools down, closer to 7:00 pm in my garden. They stay open all night long. In the fall, they develop large black seeds that are very easy to pick and save.
Flower colors come in pink, white, red, yellow, magenta, or mixed, liked speckled. They are tender perennials which means they will grow as perennials in the south. In my zone 7 garden, they should grow as annuals but mine must be in a special micro-climate because mine come back every year. For people who are north of me, they can try to dig and save the tubers for next year, or start new seed next year. I have a friend who says they are considered aggressive in southern Virginia but I have not had any issues with mine. I heard a horticulturist at a public garden in Atlanta, GA, say that they grow them for the evening visitors, who come to walk the gardens when the temperatures have cooled down.
Four o’ clocks were cultivated and selected for various colors by the Aztecs prior to the Spanish Conquest. They were then introduced to Spain and England and were in cultivation in Europe for about 200 years before Linnaeus first described the species in 1753. Thomas Jefferson received his from France. In July 1767, he noted in his journal “Mirabilis just opened, very clever.”
Try these heirloom plants for an evening garden. The seed are very easy to save so you may see some at seed swaps but if not, try these seed companies.