Before modern distractions, everyone who lived with flowers recognized that some of them opened or closed at about the same time each day. Linnaeus, the father of modern plant classification, was one of the first to publish a list arranging common flowering plants in an order that could be used as a clock. After all, sundials do not work on cloudy days, and mechanical timepieces were expensive in the eighteenth century.
Floral clocks work in any weather because the photo-sensitive plants that reflect day length actually take their clues from the length of the night, not the day. But no one understood this until much later, and Linnaeus’s list happened to include some day-neutral plants, such as dandelions, which couldn’t care less about punctuality and which change their schedule throughout their blooming season. Most of Linnaeus’s timekeepers are weeds, but his interest was in getting people to work on time, not in having them admire the clock. Whether you want bindweed, thistle, and hawkweed (5, 7, and 8 a.m. in Uppsala, Sweden, where Linnaeus lived) in your garden is up to you.
The summer sun rises earlier and sets later the farther north you are, and flowers open and close earlier, too. Unfortunately for the Victorian-era gardeners who were using his plant lists, Linnaeus lived farther north than all of Britain, the United States, and most of Europe. Consequently, floral clocks rarely produced useful results. Many Victorians ended up including sundials, simply arranging their plants according to whether they opened in the morning or afternoon. Perhaps if Linnaeus had lived in Geneva with the rest of the clockmakers, his list might have been more useful.
Counting Sunny Hours
A sundial makes a charming garden accent and, like a birdbath, actually serves a purpose beyond mere ornamentation. But whether it is a common horizontal type (meant to be mounted on a pedestal) or the less common perpendicular form (for wall mounting), a sundial must be placed with care.
- It seems obvious, but make sure the spot gets unobstructed sun all day.
- The sundial will be a focal point no matter where you put it, so put it where a focal point makes sense — in the (wide) intersection of two paths, for instance, or at the end of a long axis.
- The mounting spot must be level, and it must be accessible; if you put the sundial in the middle of a flower bed, nobody will be able to read it.
- Don’t forget about daylight savings time when you set it up. The sundial should tell the true (sun) time, even though it’s likely to be used mostly in the summer.
- To avoid mistakes, place the sundial provisionally, without affixing it to the spot, and check it every few hours for a couple of days.
- Just in case you’re fond of crossword puzzles, the part that casts the shadow is called the gnomon.