Annual flowers that re-seed themselves are a treat for hard working gardeners. We depend on our annuals and tender perennials such as Four O'Clocks to come up on their own.
Marigolds, zinnia, euphorbia, salvia, daisies, nicotiana or flowering tobacco and many more plants go through their annual cycle, dropping mature seeds on the ground at the end of the season. The seeds lie there, dormant, until conditions suit their nature and they sprout.
Some plants re-seed generously. Euphorbia marginata (Snow on the Mountain) and morning glory pop up all over the place while flowering tobacco tends to come up only where it was grown the year before.
The more plants you raise from seed, the more likely it is that you will recognize them the following year.
I planted larkspur seeds three years in a row before any lived long enough to bloom. Larkspur seeds are sprinkled in the garden between August and November. When they emerged the following February, I pulled them all out, mistaking them for weed seedlings.
Four O'Clock and Snow on the Mountain seedlings moved in five years ago, arriving with a load of compost or manure we had delivered. Each year they come back but in smaller numbers. When the beds are cleaned out in the spring, all but a dozen volunteer seedlings are removed.
As seeds drop year after year, plants revert to the appearance of the parents. The zinnia seeds we planted five years ago were multicolored and now the volunteers produce mostly solid pink flowers. The first year the Four O'Clocks bloomed, the flowers were pink with yellow centers and now they are almost solid pink.
Four O'Clocks are also known as the Marvel of Peru or Mirabilis Jalapa. Mirabilis means wonderful and Jalapa is Mexican town. Their Four O'Clock and Beauty of the Night names come from the fact that the flowers open in the late afternoon and close when the sun hits them. When it is cloudy, the flowers remain open all day. The Marvel of Peru name is because the plant was originally found in the Andes Mountains of Peru in 1540.
There are 50 Mirabilis annuals and perennials that grow in Central and South America and the U.S. We treat Four O'Clocks as annuals, replanting the seeds every year, but they are actually tender perennials, cold hardy to zone 8 or 10. The tuberous roots could be dug up after frost and protected during the colder months, then replanted in the spring, like dahlias.
The plants become fairly large and branched. By this time of year, the ones in full sun are 3-feet tall and and up to 2 feet wide. The plants in half shade are flopping over but still blooming their hearts out.
The 1 to 2-inch trumpet shaped flowers come in red, pink, violet, yellow, white, speckled, striped and multicolored. Since they flower at night their pollinators are moths.
The 2 by 4-inch leaves are deep green, so the plants quickly fill an open spot in the garden. Once they are established, they will continue to bloom even if you forget to water them.
The seeds can be started indoors 6-weeks before the last frost in 70 to 80 degree soil. They can also be planted directly into the garden when the soil warms in April.
Renee's Garden Seeds - www.reneesgarden.com - has the new Broken Colors variety. The Jefferson Monticello store - www.monticellocatalog.org - offers heirloom colors. Park Seed - www.parkseed.com - offers Limelight that has hot pink flowers and lime green leaves.
If you grow re-seeding flowers, move some of the seed heads to other places in the garden this fall. Just lay them on the ground and watch for tiny plants next spring.