Unlike bananas, peaches and plums, citrus fruits stop producing sugars the day they are picked. So the longer they hang on the tree the sweeter they are.
Gardening by the Yard host Paul James tastes his way through the citrus groves of the University of California in Riverside with his guide, Otilla Bier, citrus field director. The citrus collection at the university has over 900 varieties with new ones added every year.
The first taste test is the Nordmann seedless 'Nagami' kumquat, a tantalizing blend of sweet and tart, all the more tempting because it's not yet available in stores. Kumquats are in the same family as oranges but belong to the genus Fortunella and are hardy to 10 degrees Fahrenheit.
Next Paul tastes a mandarin that also has not yet been released. It was developed by the USDA and is currently known as USDA 88-2. "Deliciously sweet," pronounces Paul. And then to compare, he samples another mandarin known as 'Yosemite Gold', developed in Riverside. It’s mostly seedless, easy to peel and also delicious, according to Paul.
"This tree doesn't even look like citrus to me," comments Paul at the next stop on the tour. "It looks like a small ornamental tree you might find in a landscape." Otilla identifies it as a 'Myrtle Leaf' citrus. "It's grown for its form and abundance of colorful fruit," she says.
How does it taste? "Quite pleasant" is the verdict according to Paul.
Then there's the 'Dekopan', a very new variety of citrus in the United States that features a "neck." And the taste? "It's the most uniquely flavored of all the fruits I've tasted today," states Paul. In Japan just one of these popular fruits can go for up to nine dollars!
Last on the citrus-tasting circuit, the pink-fleshed 'Cara Cara'. It's a naval orange just discovered growing in Venezuela. Its pink flesh comes from lycopene, a potent antioxident found in tomatoes.
Growing Citrus in Containers
So how do you grow your own citrus if you don't live in zones 9 or 10? Containers! Even in cold northern climates you can grow many varieties of citrus in suitable containers.
Be sure your container is about twice the width of the root ball to allow the roots to spread out without having to repot. Also make sure your container has a hole in the bottom as citrus requires excellent drainage to thrive. Place mesh screen over the drainage hole and fill the pot half full with a potting mix that contains perlite for drainage, peat moss and a lot of sand for weight, because fruit-laden citrus trees get top heavy. Add a handful of slow-release fertilizer that's low in nitrogen but high in phosphorus to promote good fruit formation; if you garden organically, kelp or fish emulsion works well.
Place your tree in the prepared container and fill the remaining space with more potting mix.
Firm the soil so the tree is stable. Be careful not to plant the tree too deep: the easiest way to kill a tree is to plant it too deeply. Place ornamental pebbles on top of the soil if you like, to keep the soil from splashing when the tree is watered.