Once just an old Southern tradition, the blue porch ceiling has made its way north and is being introduced to new generations. There are numerous theories as to why – from fooling spiders and wasps into thinking the ceiling is the sky, to blue being a harbinger of good luck, to the color extending daylight, to scaring away evil spirits.

In the Northwest, aurora blue is a popular shade for the porch ceiling. It's associated with the Aurora Colony, a Christian communal society that gained popularity in the 1850s.

Blue porch ceilings are also quite prevalent along the east coast, from Boston to Philadelphia and other historic cities, where Victorian and Colonial homes abound.

Sky blue ceilings were a popular color scheme for the Victorians, who preferred the colors of nature when painting their homes. Mustard yellow, ochres, browns, olives, terra cotta and the color blue were commonly used in exterior paint schemes. The warm earth tones reminded the Victorians of the outdoors around them, with the blue reserved for the porch ceiling to remind them of the blue sky even when the days were overcast and gray.

Blue ceilings are popular and have been popular in the South for centuries. “Porch ceilings have always been blue in the South,” says Lori Sawaya, an independent Principal Color Strategist. “People continue to paint their porch ceiling blue because that's what their grandmother did, and that's what her grandmother did.”

But many Southerners suggest that blue porch ceilings originated out of the fear of haints. Southerners, especially in the area of South Carolina, have a name for the ceiling paint used on porches – the soft blue-green is referred to as “Haint Blue.”

“Haints are restless spirits of the dead who, for whatever reason, have not moved on from their physical world,” says Sawaya.

Haint blue, which can also be found on door and window frames as well as porch ceilings, is intended to protect the homeowner from being “taken” or influenced by haints. It is said to protect the house and the occupants of the house from evil.

Some people swear that blue paint repels insects, leaving a porch bug-free and pleasant during those long summer evenings and afternoons. Most credible sources discredit this belief. However, this belief could be seated in historical truths.

When blue paints were first used on ceilings, they were usually milk paints, and those paints often had lye mixed into the composition. Lye is a known insect repellent, which would explain why insects would avoid nesting on a painted porch ceiling or ledge. As milk paint has a tendency to fade over time, giving it a rustic look, people would usually need to repaint their home every year or few years, covering the existing coat with a new coat of paint, and fresh lye.

But many still theorize that insects prefer not to nest on blue ceilings because they are “fooled” into thinking the blue paint is actually the sky.

Haints and insects aside, many people choose to paint the porch ceiling blue simply because of the way it makes the room look and feel. Blue is a calming color, so using it to paint an area of the house that's intended for relaxation makes sense. Throughout the U.S., porches are often a favorite place while the weather is warm, or even hot, to sit and watch time and life go by. When sitting on the porch, it can seem as though life has taken on a slower pace, as though relaxation is a must.

People may also paint the porch ceiling blue because the color seems to emulate the natural sky and makes the daylight hours feel as though they last just a little longer. “Light blues especially lighten and brighten space and propagate any light that you do get, because of the basic nature of color,” says Sawaya.

Most paint experts agree that the best shade of blue is the one that fits the look of the house. “You don't want [a blue ceiling] to look like an afterthought or like it came out of nowhere,” cautions Zoe Kyriacos, architectural color consultant for Colors by Zoe in Takoma Park, Md. “You want to make it look like it was part of the package.”

She says blue can be used on any style of house; it just depends on the blue. “A traditional house would use a more traditional color, something lighter. On a contemporary house you can do something bolder, something brighter.” Kyriacos prefers blues with hints of other colors, which make the blue more complex and interesting, she says. A blue with a drop of red in it, for instance, adds “a little warmth.”

Also consider the natural light. Colors tend to get washed out when used outdoors, so there's a little wiggle room to go darker than you would indoors.

Sawaya recommends three shades of Sherwin-Williams paint to those looking to paint their own porch ceiling blue:

• SW 6471 Hazel
• SW 6505 Atmospheric
• SW 6944 Pool Blue

• Art First: Custom and Historic Colors for Architecture
• Bob Vila's Guide to Historic Homes of the South by Bob Vila. (Quill, 1993)
• House Colors by Susan Herschman. (Gibbs Smith, 2007)
• The Preservation of Historic Architecture: The U.S. Government's Official Guidelines for Preserving Historic Homes by Department of Interior. (The Lyon's Press, 2004)