Cultivating Citrus

Though they’re not at all native to the Ohio Valley, citrus trees can be grown here, with delicious, fragrant, beautiful results.

Of all the fruits, those belonging to the citrus family carry the strongest connotations of health and paradise.

All citrus descends from four Asian fruits: the citron, mandarin, pomelo, and papeda. References to citrus appear in Sanskrit and Chinese texts of the 8th and 9th centuries BC.

But citrus also seems to be constantly reinventing itself. The grapefruit, for example, a hybrid formed from the sweet orange and pomelo, is just 300 years old. That’s in part because members of this genus easily cross-pollinate with other citrus species, and are prone to genetic mutation, which growers have been quick to exploit. The Ruby Red grapefruit, for example, is a naturally occurring pink grapefruit that producers expose to radiation to trigger the deeper red hue.

From Himalayan origins, citrus was carried west on the Silk Road to become a global, nutritious commodity. Limes staved off scurvy among seafarers. For their richness in Vitamin C, orange and grapefruit juice were promoted during the war years as a weapon for victory.

Growing Citrus in the Ohio Valley

The practice of growing subtropical citrus fruit in temperate climes goes back to the “orangeries” kept by wealthy Europeans. These well-lit and heated conservatories were filled with living bling in the 17th and 18th centuries. In 1629, apothecary and horticulturist to the royals John Parkinson recommended that the would-be citrus grower plant trees in boxes on rollers so that they could be moved indoors in winter.

That and other cultivation methods haven’t changed much since, although today’s growers have a much broader palette of plants to choose from, including indoor-friendly dwarf varieties. Citrus doesn’t have to be difficult in the Ohio Valley. It’s easy and rewarding to overwinter in your home. Citrus plants here might be more aesthetically pleasing than functional, but what’s wrong with that? While they may not keep you in marmalade year-round, as an ornamental indoor-outdoor hobby plant, they bring a strange and intricate beauty to your spaces, delighting you with bright flowers, fruit, and a heavenly smell. Growing citrus trees presents an appealing challenge: the promise that with care and nurturing, you just might just find yourself with enough fresh fruit for cocktails or a Key lime pie.

Greenacres Foundation marketing manager Peter Wheeler is a transplant from San Diego. When he and his native Cincinnatian wife moved here, Wheeler brought along his potted citrus trees. “I grew up being able to walk out in the back yard and pick an orange or a lemon like it was nothing,” he says.

The leaves of his thorny Kefir lime are a prized ingredient in the Thai and Vietnamese food he loves to cook. He has a Meyer lemon-Key lime tree, a.k.a. the “Cocktail Tree,” which combines those two varieties. Because his wife loves the fruit, he recently acquired a dwarf Cara Cara navel. This he bought from Hirt’s nursery in northern Ohio, which he recommends as a resource for the home citrus grower.

Get Wheeler chatting about growing these and other tropical plants, and you immediately sense his enthusiasm for the experimentation and technique he brings to growing plants several USDA Hardiness Zones removed from where they can be safely planted in the soil.

Soil, Light & Water

“Root health is the absolute thing you’ve got to pay attention to with potted plants,” Wheeler says. For citrus, he uses a lean, well-draining cactus potting soil and, in order to keep roots compact but healthy, contains them in Superoots air pots. Roots encountering air in these perforated pots “air prune” and curve back on themselves, restricting trees to the 4- to 5-foot range that Wheeler prefers. With these, he cautions, “you just need to be really careful about your watering schedule because they are aerating so much that they can dry out a lot faster.” In winter, Wheeler also gives his plants an added dose of light under full-spectrum bulbs or LEDs.

But you don’t have to use lights or high-tech pots. Rootballs can be hand-pruned. And when it comes to getting your citrus the lumens they crave, you have options.

I’ve often lingered over the glossy and fragrant lemons, limes, and kumquats in the tropical section of AJ Rahn Greenhouses on Grey Road. The majority of citrus carried by this horticultural cornerstone of the region, says Rahn’s retail associate and tropical expert Mychael Rumping, are dwarf or shrub varieties. An avid collector himself, Rumping keeps some 200 houseplants.

“Citrus is a very easy, low maintenance house plant as long as you have the sun for it,” Rumping says. “I tell people put them in a south- or west-facing window if you want to keep them foliated and flowering throughout the winter, which is a good idea if you are trying to get fruit.”

But if your house or apartment doesn’t have great light, don’t fret. Rumping goes another route, letting his citrus trees rest through the low-light months. “They’ll defoliate and just essentially go dormant like any other deciduous tree would during the winter. And then when you put them outside in the spring and the summer, they come back with a vengeance.”

Rumping’s citrus plants summer and flower outdoors. Beginning in April, he treats them monthly with a generalized houseplant fertilizer, until August, in anticipation of putting them into dormancy. He doesn’t want root growth during the winter. After a summer fraternizing with bees, he uses the elements to send them into dormancy by “allowing them really big temperature swings,” he says. For most indoor/outdoor houseplants, the rule of thumb is to bring them in when temperatures dip below 50°, but with his citrus he leaves them out until it cools into the 40s. Colder temperatures start the defoliating process, putting the plant to sleep. Rumping also lessens but does not entirely cease watering to signal the plant to slow down.

When moving them indoors, he suggests treating them with a triple-action spray to prevent pests from piggy-backing in. When they slow for the colder months, Ramping’s citrus plants don’t entirely lose their leaves, which is why he cautions against completely depriving them of light, as with plants overwintered in one’s basement. If you notice brown leaf edges, he says, set up a humidifier. Placing pots on a gravel tray also helps maintain reasonable humidity when the air gets dry. This style of overwintering helps plants conserve resources so they’re ready to come back when put out in the spring.

“If you really think about the place that you’re wanting to put a plant, you’re going to find something, no matter the light requirements or the ease of care that you need to fit your lifestyle. There’s something for everywhere. Just ask the people who know, wherever you go,” Rumping says.

Rahn’s assistant grower and tropical plant specialist Michelle Lynn has 26 years of experience in the nursery business. The last 12 of those she’s worked at Rahn’s, and seen a surge of interest in houseplants among millennials. Lynn shows me around the tropical section. There’s a variegated kumquat loaded with subtly streaked fruit. A Persian lime that is glossy green with pale yellow flesh. There are Key limes and Meyer lemons and a miniature calamondin orange tree in full, meaty flower, redolent of jasmine and sandalwood. “Yeah, the smell on this is fantastic,” Flynn says when I stick my schnozzle into the blooms.

For beginners she recommends the Meyer lemon, which is probably the citrus most commonly grown indoors. It isn’t a true lemon at all, she says, but a cross of citron and mandarin/pomelo hybrid. Kumquats and calamondins are also easy to maintain, she says.

Light is paramount—they need a site that gets good light at least six to eight hours a day. Water is important, too. “When they’re fruiting you have to be consistent with the water, because they need the moisture to grow the fruit, swell it up,” Lynn says. Regular water also prevents them from dropping fruit early. If the leaves turn a little bit yellow, they need iron, she says. Lynn recommends feeding plants with a water-soluble supplement like Citrus Tone.

Even with all her experience, Flynn says it’s still “kind of trial and error. I put them in the bright window and usually they’re fine. A lot of times we’ll grow them in the clay pots because they’re a lot easier to keep up, especially in the winter time. You don’t make that mistake of getting them too wet and they breathe a lot better. The winter time is the most stressful because of the lack of humidity in the house.”

Potted citrus are quite affordable. But if you open yourself to the spirit of experimentation and trial-and-error shared by Wheeler and Flynn, possess some patience and can borrow a well-lit windowsill, homegrown citrus can be 100% free. One caveat: Despite being self fertile, meaning you only need one tree to generate fruit, citrus plants raised from seed indoors can be finicky to get to fruit. But why let that keep you from trying?

The Farmer’s Almanac suggests soaking seeds from your favorite citrus fruit overnight, then planting them in a half inch of moist potting soil. Leave this covered with a plastic bag or wrap in a warm, sunny spot until they show signs of life. At this point, the cover should be removed, and the pot left by the window. Feed young plants regularly with a balanced fertilizer.

Lemon trees can live 50 to 100 years. While container plants don’t have quite that life span, you never know. That tiny seed on your sill—because, “when life gives you lemons,” right?—might bring decades of beauty and enjoyment, as well as tasty conversation pieces, to your life. 

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The Varieties of the Citrus Experience

Bearss (aka Tahitian or Persian) Lime Less acidic and bitter than many lime varieties.
Calamondin Grown as an ornamental. Produce orange, sour fruit.
Citron Yellow fruit with a rough surface and fleshy rind. Not juicy but sweet.
Eureka Lemon Produces round, thick-skinned, gold colored and acidic fruits.
Kaffir Lime Grown for leaves used in Thai and other Southeast Asian cuisines.
Kumquat Pungent flowers are good for your mood. Its tart fruits make delicious marmalade.
Limequat Yellow fruit with edible skin that can be popped right in your mouth.
Mandarin A tangerine known for fragrant flowers and sweet fruit.
Meyer Lemon This hybrid came from China just over a century ago. Fruits are juicy, thin-skinned, and sweeter than lemon.
Satsuma This thin-skinned tangerine came to the West from Japan.
Tahitian Orange A dwarf tree with fruits that are less acidic.