Plant Some Seeds of Four O'Clocks for a Floral Clock a la Linnaeus

Four O'Clock's are an old fashioned annual flower that blooms in the afternoon and closes at night. Marvel of Peru gives a clue to the reason they are annuals in our zone 7 weather - they are from areas where the weather is Peru-like - no freezes in the winter.

The seeds are large and come up in a week or two. The plants grow 3 to 4 feet tall in my garden by the end of the summer. I probably should pinch them a few times to prevent that end of the summer leggy look but I never get around to it.

Mirabilis is the Latin name for these summertime beauties. It means wonderful. They are very easy to grow so they are a good choice for a child's first garden. Plus the fluttery things are attracted to the flowers on sunny afternoons - hummingbirds, butterflies and skippers will visit the open blooms.

At Yale.edu there is a fun article from 2006 on Mirabalis. According to the author, Eric Larsen, who found the information on the BBC site, you can plant a floral clock garden for hourly sequential flowering.

Here's an excerpt and the link so you can read the rest of the article.

The idea that one can design a floral clock has intrigued generations of garden designers since Linnaeus proposed the idea back in the 1700s. It is doubtful whether Carl actually planted a garden where the flowers were arranged so that they would announce the time of day by their successive flowering, but his son worked on the idea more fully after the elder Linnaeus' death.

In Philosophia Botanica, pere Linnaeus classified different plants by the types of flower production. For instance, Meteorici have flowers that open and close by weather conditions.

Tropici are flowers that open and close depending on the length of the day. Aequinoctales are plants that bloom at a fixed time of day unaffected by weather conditions.

These of course are the plants one would choose from when designing a floral clock.

Back in the 19 Century, it was all the rage to plant floral clocks, which were basically a circle divided into twelve with plants in each segment that would flower. Below I provide a partial list of plants that would work for your floral clock project. Bear in mind that some plants would need to be replaced as their season of bloom passes.

2:00 AM Night blooming cereus closes
5:00 Morning glories, wild roses
6:00 Spotted cat's ear, catmint
7:00 African marigold, orange hawkweed, dandelions
8:00 Mouse-ear hawkweed, African daisies
9:00 Field marigold, gentians, prickly sowthistle closes
10:00 Helichrysum, Californium poppy, common nipplewort closes
11:00 Star of Bethlehem
12:00 Noon Passion flower, goatsbeard, morning glory closes
1:00 PM Chiding pink closes
2:00 Scarlet pimpernel closes
3:00 Hawkbit closes
4:00 Four o'clock opens, small bindweed closes, Californian poppy closes
5:00 White waterlily closes
6:00 Evening primrose, moonflower
7:00
8:00 Daylilies and dandelions close
9:00 Night blooming cereus

The list above is from a BBC web-site, hence some of the English-sounding names. Your observations and thoughts are welcome on the times of flower opening, floral clocks or any other subject.

There is a variety called Broken Colors, with multiple colors, shades and hues on the flower. Another flower on the same plant will be completely different. This plant isworth growing if just for the flower colors, but add the aroma and you have a surefirewinner.

Plant of the Week is a publication of the Marsh Botanical Gardens. Opinions expressed herein do not reflect on the official policies of Yale University. We also welcome guest columnists, contributions and salty snack products.
Until next week, Trying my best to entertain - Contact: Eric Larson (eric.larson@yale.edu)