Just as winter settles in for the long, dark haul, suddenly it's citrus season. The colorful, sweet-smelling fruits are a pleasant reminder that somewhere the sun is still shining.

Just as winter settles in for the long, dark haul, suddenly it's citrus season. The colorful, sweet-smelling fruits are a pleasant reminder that somewhere the sun is still shining.

So why not grow your own bit of winter sunshine? Rogue Valley citrus enthusiast Tom Ponder says that growing citrus indoors is a fun hobby with some sweet perks. Citrus trees make fragrant, decorative indoor plants that also produce a small amount of fruit. They can be kept as small bonsai shrubs and placed in a south-facing window, or grown outdoors and sheltered from the most intense freezes. Ponder and his wife, Glenda, grow more than 15 varieties of citrus in two small, crowded greenhouses at their Abbie Lane Farm near Gold Hill. The trees are productive enough that they sell small quantities of Meyer lemons, finger limes and kaffir limes through the winter and early spring, as well as seedlings.

Growing citrus indoors is not a new fad of the petroleum age. Italians introduced the practice back in the 13th century, moving potted plants into designated rooms called limonaie not only to protect the plants from chill, but so royalty could enjoy the delicate blooms and ambrosial aroma of winter flowering.

King Charles VIII introduced the limonaie to French aristocracy, and from there the indoor citrus garden, or orangery, became a must-have for the European elite.

George Washington built an orangery at Mount Vernon, and until an 1867 fire, U.S. presidents enjoyed an orangery appended to the White House.

The Italians may have been on to something else, too. According to studies by the Mayo Clinic, just the smell of grapefruits, oranges and lemons can ease anxiety and depression. It's no wonder a glass of fresh orange juice on a cold, gloomy morning is like a shot of summer.

In recent years, personal orangeries have been making a comeback, along with interest in varieties slightly more exotic than the standard Navel or Valencia. Martha Stewart wrote about her own miniature orangery in a 2009 blog post featuring a Striped Lemonade lemon, and since then most major gardening magazines have written about indoor citrus plants.

Many recommend the Meyer lemon, a sweet, juicy lemon making a pricey appearance at grocery stores. It's considered relatively cold hardy, and with its fragrant white and purple flowers, an attractive choice for bonsai.

Last year, the Ponders sold more than 50 citrus seedlings at the Master Gardener's Spring Garden Fair in Central Point, most of them Meyer lemons.

"Most people want their Meyer lemon, I can understand that," he said. "I like the finger lime myself."

Ponder likes to experiment with a diversity of cold-hardy citruses, such as the bizarrely twisted Buddha's Hand, or the latest super food from Japan, the Yuzu. It may be cold outside, but growing citrus keeps Ponder's green thumb from getting frost bite.

Most of the time the trees don't require additional heating in his unheated greenhouse. Citrus trees in general tolerate the cold better than we might imagine. In fact, oranges wouldn't be orange without a few hundred chill hours. Grown in the tropics, citrus remains green until maturity, never developing those cheerful pinks, reds, yellows and oranges that brighten our kitchen counters in winter. The very cold hardiest of the citruses, a cruel-looking plant with long, curving thorns called Flying Dragon, can survive temperatures of -20 F. Even some kumquats and mandarins can handle temperatures down to 10 F. The problem is that at such extreme temperatures, the water-rich fruit and flowers freeze solid and die, leaving a barren, if alive, tree. When thermometers around the valley plummeted earlier this month, Ponder kept his trees cozy with a space heater.

It's these occasional, extremely cold freezes that make the Rogue Valley an improbable place to find citrus growing outdoors at all, much less on a commercial level, says David Sugar, a tree-fruit specialist at the Southern Oregon Research and Extension Center on Hanley Road. He's heard of people growing backyard lemon trees along the coast as far north as Seattle, where the maritime climate rarely brings hard freezes. Yet a few citrus trees are known to grow in valley soil. One of the oldest grows behind the Rogue Creamery in Central Point, a 10-foot-tall lemon tree that has weathered at least 20 winters thanks to an impromptu greenhouse constructed every winter from plywood and clear plastic sheeting. Lead cheesemaker Craig Nelson says they tried using the very locally grown lemons, which are in season all year, but the result was a very sour cheese.

Lemons, limes and other naturally sour and small fruits tend to fare better in Oregon's low-light winters, says Sugar. He recommends mandarins, such as satsuma or clementines, which are commonly grown in Northern California and known to sweeten up without much heat, as well as kumquats and their hybrid relatives — orangequats, limequats and mandarinquats. Exotic lemons and limes are a great choice for those who like to cook, as the zest and leaves can also be used to add a fresh zing to recipes.

To make your own personal orangery, first assess your space needs. For indoor plants, choose a tree made from a cutting rather than grafted onto a rootstock, as it will be smaller, bushier and produce more fruit. Trees with variegated leaves, such as calamondin, make decorative houseplants or ornate bonsai. There are literally hundreds of varieties of limes, lemons, tangerines, mandarins, kumquats, grapefruits, pomelos, tangelos and oranges to experiment with, so get creative and try something new. Each variety flowers and fruits at different times, potentially allowing fruit or flowers all year round — a little breath of perpetual summer.

Lindsay Gasik is a freelance writer with a fascination for fruit. She is the author of www.yearofthedurian.com and is currently fruit hunting in Australia. She can be reached at durianyear@gmail.com.