Q. Mike: When I was a horticulture student at the Barnes Foundation (in the Philadelphia suburbs) I picked up a couple of Hardy Oranges from a specimen they had there. I successfully started the seeds, grew the plants in pots for years and then planted one outside. This tree is gorgeous. Last year I got my first fruit, and this year, there are over a hundred fruits. I'm moving to Asheville North Carolina next spring and I'd like to take some seed with me to plant at my new place. I tried saving some seeds last season but they dried out. Short of planting them now in pots, which I'd rather not do, is there a way to preserve the seeds and keep them viable for future plantings? Thanks!
----Ron; just north of Morgantown, PA.
A.'Hardy orange' sure sounded like an oxymoron to me, as I "know' that citrus fruits come from plants that thrive where it don't never freeze—like down in Southern California, and the hot parts of Arizona, Texas and Florida. But I've also heard other people talk about 'hardy oranges' and 'hardy citrus', so I turned to our frequently-relied-upon fruit expert Dr. Lee Reich, who—as usual—smartened me up on the subject.
"Hardy orange," explains Lee, "is the common name for a plant--Poncirus trifoliate--which is hardy outdoors, even north of Philly—down to USDA Zone 5 perhaps. Also known as 'Trifoliate orange', it's not a true citrus, like lemons and limes, but it is a citrus relative and it's frequently used as a rootstock for grafted citrus trees because of its exceptional hardiness. It even looks like an orange tree in fruit, leaf, and flower. Unfortunately, the fruit is barely edible."
So you can grow a tree that looks like an orange tree and produces fruits that look like oranges, but you can't actually eat them.
"Well, they're not poisonous," says Lee. "The fruits have a taste that's vaguely reminiscent of an orange, but bitter. Some people use the fruits to make marmalade, but that may just prove the old theory that any fruit tastes good if you add enough sugar to it. But the tree is fragrant—both the flowers and the fruits have a wonderful scent.
"There's a also a variety called "Flying Dragon" that is awesomely ornamental," adds Lee. "It has very attractive green fruit, the stems swirl around in a corkscrew shape, and it has amazing 'recurved' thorns. The whole plant really looks 'dragonish'." (Lee sent us a photo of his potted "Flying Dragon" that proves this description is not an exaggeration.)
So—will our listener's hardy orange come tree from seed?
"Probably", says Lee. "But he has to plant the seed immediately, while it's still fresh—and I mean right out of the fruit. When the fruit is ripe, he should pick some and plant the seeds in a light-soil-free mix in small pots. As you know, you can tell citrus is ripe when the fruit comes easily off the branch with a gentle tug."
Yeah. Sure. I knew that.
"Now," adds Lee, "hardy orange is a fun plant to grow, but there is also a category called 'hardy citrus': Poncirus hybridized with other citrus and citrus relatives (like kumquat, which is also not technically a true citrus) to make hardier, more edible plants. I list a few of these in the citrus section of my book "Grow Fruit Naturally" (The Taunton Press; 2012), like the Citrange—a cross between a hardy orange and a true sweet orange that tastes like a slightly tart true orange. It's hardy down to 5 or 10 degrees F., but you still probably couldn't grow them outdoors for reliable fruit north of Georgia. Winter hardiness is one thing, but you also need a long growing season to get fruit that you can eat.
"You need to choose your plants carefully if you want to try and grow edible citrus outdoors outside of its normal range," stresses Lee. "The trees can be real backyard fun, and it's nice to grow your own fruit—but there's a reason these plants are uncommon.
"However," he adds, "growing citrus in pots that can be brought indoors for winter is a whole other story that opens up many possibilities for really tasty fruits. You can keep the plants to a workable size by repotting them and trimming back the roots every few years; just be sure the plant doesn't get more than three times taller than the height of the pot. The best winter situation is bright light, but in a somewhat cool room—that way you give the plants a little rest, which promotes stockier growth."
A frequent contributor to the Gardens Alive Question of the Week, Lee invites you to check out his new videos: http://www.youtube.com/leereichfarmden and a PBS thing he did: http://www.growingagreenerworld.com/weedless-gardening/