MAGICAL MOON VINE
It was late on a September evening when Peter and I returned home from our first evening out after being away for almost a month. As we pulled into the drive, I glanced out the side window and wow! The moon vine seeds that had been planted months before had gone from spindly Cinderella seedlings into a magnificent princess’ gown covered in white satin. We counted almost two dozen bright, pearly discs, each as wide as a hand span. The suddenness of the discovery made it all the more delightful. Springing from the car, we rushed over to enjoy the delicate beauty and subtle fragrance of this garden treasure.
Moonflower (Ipomoea alba) is a night-blooming tropical vine that we must grow anew each year from seed. A packet at a garden store last spring was $1.99 and contained enough garbanzo-bean-sized seeds to plant in four places in my garden and to share with several friends. The highly visible spot along the drive, in full sun, seems to suit it well. This vine requires support, with a fence, trellis or tree to clamber up. Plant them near the house so you may enjoy their soft fragrance and sudden bud opening in the evening. Blooming as the days shorten, moonflower doesn’t start to bud until late in the summer and will continue to bloom until frost. The best floral bounty comes if you fertilize regularly as it is a heavy feeder. You would be, too, if you grew 10 feet tall in one season.
In the same genus as moonflower are the dayblooming annual morning glories. There are several popular Ipomoea species, including the Japanese morning glory (I. nil), tall morning glory (I. purpurea) and grannyvine (I. tricolor). The strikingly showy, dayblooming, white ‘Pearly Gates’ is often companionplanted with moonflower to give both day and night flowering on the same trellis. One of my favorite cultivars is ‘Heavenly Blue,’ with large, clear azure blue photogenic flowers. Julie is fond of ‘Chocolate,’ with rosy, brown discs. Soak Ipomoea seed for a few hours in warm water before sowing indoors. All the Ipomoeas like it warm, so never plant out before the soil is warm. A caution with any of the morning glories—they may be self-seeders that return unbidden.
Two more attractive members of this big genus are cypress vine and cardinal vine. While the names tend to be used interchangeably, they actually represent two distinct species: I. quamoclit and I. multifida, respectively. Both play well with others and have ferny foliage with red, tubular flowers that are very popular for hummingbirds. It is available in pink- or whiteflowered varieties. It may self-seed, but is not aggressive in the garden.
THE GENUS IPOMOEA
There are more than 500 wild species of Ipomoea worldwide, with thousands of cultivars. Most are vines, but some are woody, including a few lovely trees, like the one we saw in the gardens at the Taj Mahal. The genus includes many gorgeous ornamental plants such as morning glory and moon vine. In addition to ornamental value, Ipomoea includes some important food crops. Among these, sweet potatoes were first domesticated in Mesoamerica some 5,000 years ago, and were spread throughout the Pacific by cuttings and roots. The true sweet potato, often incorrectly called yam (true yam is Dioscorea, which is not related), with high levels of vitamins and protein, is one of the most important food crops in developing countries.
The outer skin of edible sweet potatoes may be purple, red, brown or beige. Interior root flesh may be white, ivory, yellow, light orange, deep orange or purple. Flesh quality also is divided into two types: the wet, sweet creamy kinds and dry, mealy ones.
To select a sweet potato variety for your garden, choose one with a bush or bunch growth habit unless you plan to give them a lot of running room. Sweet potatoes are tropical perennials that thrive on heat. The warmer the soil, the faster they will bulk up root mass. Grow them only in full sun. An underlayment of black plastic, put out two weeks before planting, will help take the chill out of the soil, and then the vines will cover it before the worst August heat. Sweet potatoes will not tolerate frost, so harvest before the first cold snap comes.
Sweet potatoes are as common in China as roasted chestnuts are in Rome, and Asians have a love affair with this culinary delight. On our recent Missouri Botanical Garden trip to China, we were served a delightful dish that was new to me: a plate of little lavender crème cubes of rich, smooth, melt-in-yourmouth sweetness—a mousse of pureed taro and purple sweet potato, enriched with the smoothness of whipped cream. Purple sweet potatoes also are popular in Hawaii, Japan and the Philippines. Try the purple potato chips next time you visit Maui.
Throughout Asia, locals enjoy a fresh green vegetable that grows in moist soils or in water. Called water spinach or water morning glory (Ipomoea aquatica), the kinship to other Ipomoeas is clear when they bloom. The Chinese have a way with water spinach. It is often stir-fried with garlic or fermented tofu. In Vietnam, it is the main ingredient of Mekong sour soup. In the Philippines and Japan, it gets battered and deep fried. While cultivated for thousands of years in Asia, it is an invasive water plant in the Southeast U.S. and is a federally listed noxious weed, so don’t put this one in your garden.
KIDS AND SWEET POTATO CULTURE
When I was about 4 years old, my Southern daddy showed me how to put a ring of toothpicks into the sides of a grocery store sweet potato, balance it on a jar of water with the top sticking halfway out, and grow a voluptuous windowsill-filling vine. After it sprouted lushly, we took slips (tip cuttings), to root and plant out in the garden. It was my first experience with vegetative plant propagation and helped me to learn about how plants are shared and perpetuated. If you want to do this demonstration for your young children or grandchildren, be sure to get an organic sweet potato as most regular market roots are treated with a chemical sprout retardant for longer shelf life.
SWEET POTATO PONE
The best tasting edible sweet potatoes in the U.S. come from North Carolina. I may be a little biased, but my home state does have the largest domestic sweet potato production in the country. My great-aunt, ‘Miz Pat,’ who lived near Raleigh, made a dish called sweet potato pone. It was a delicious, rich casserole that started with a thick bed of homegrown, raw grated sweet potatoes. Layered into that was an upholstery of a butter-and-egg crème, slightly sweetened with brown sugar and fragrant with citrus, allspice and nutmeg. It was a dish she prepared often during the holiday season and remains a family favorite. All I know is that this recipe is where my love affair with the genus Ipomoea began—in this fragrant, savory casserole and with the lush vine growing on the window sill, propped with toothpicks. Patricia Raven, Ph.D., has a doctorate in ornamental horticulture and Julie Hess is senior horticulturist at the Missouri Botanical Garden.