For thousands of years the sun was the only way to keep time. Many societies used sundials of varying types to mark time by the sun. Nowadays, we have watches and atomic clocks to keep time for us, but sundials are still around. Sundials are a beautiful addition to any home garden, but using them to keep correct time can be complicated. Knowing that, putting in the time to correctly align your sundial can be a very rewarding experience.
Level off a full-sun area in your garden. The angle of the sundial in relation to the horizon does matter, but will not greatly impact the accuracy of your sundial. If you wish to ensure complete accuracy in the placement of your sundial, see the NASS page listed in the Resources.
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On a clear night, locate the north star and orient the gnomon, or shade arm, of your sundial to be directly in line with the north star.
If you cannot see the north star where you live, it is easiest to set up your sundial on April 15, June 15, September 1 or December 25. These are days when clock time and solar time match up. Simply align the sundial so that the shadow of the gnomon falls on the marking for noon.
You can use a compass to find magnetic north, but note that this will not be the same as true north. To accurately set up the sundial you will need to account for the magnetic declination of your area. See the NASS page listed in the Resources.
Some garden ornament sundials are not set up to correctly tell solar time. To check if the one you have meets expectations, visit the NASS website under Resources. If you live near the edge of your time zone, the sundial may be off of clock time by as much as 40 minutes. If you live in an area that participates in daylight savings time, remember that during daylight savings time your sundial will be off by one hour.