Sweet Potatoes: Warning, Some Plant-Geek Spoken Here, Many Words
The temperature dropped a few weeks ago just in time for us to get our hands in the dirt and haul in sweet potatoes. There is nothing quite like the cool soil on your hands after a long summer of 90 degree weather. It’s like putting your feet up after a long day of 3 months. It is especially satisfying that getting nice and dirty will result in feasting on one of my favorite foods.
This year’s harvest was over 4,120 lbs: a decent overall yield for us relative to what we planted, but what is noticeable is the size of our sweets. Much larger than usual. In fact we grow our sweet potatoes on tight spacing because they are much more friendly in the kitchen when they are small- and medium-sized. Many of us prefer when each sweet is a serving size – great for baking or microwaving and then serving immediately. Skip to the bottom if you’re just trying to figure out what to do with a big sweet potato. In the meantime, I’ve been reading up on these specialized roots.
Often confused with yams, sweet potatoes (Ipomoea batata) are morning glories with big, specialized roots. They are not yams, which come from a different family, Dioscoreaecea, entirely, are monocots more closely related to lilies and grasses, and comes from Africa. Sweet potatoes are indigenous to the Americas and are dicots. Unlike potatoes and yams, which are actually “tubers” and unlike onions, which are actually “bulbs” sweet potatoes are “food storage roots” (as opposed to water-storage roots, which make for a pretty cool plant biology chapter). Most roots and stems store some food, but in certain plants, the roots are enlarged and store large quantities of starch and other carbohydrates, which can be later used by the plant for growth. In sweet potatoes, extra cambial cells develop in parts of the xylem of the branch roots and produce large numbers of parenchyma cells, which causes the roots to swell and provide storage space for the starch and carbs. The same thing happens in dandelions and salsify (which you’ve been avoiding at the Farm Stand)—this is different than how carrots, beets, turnips and radishes work, where the food (and food storage tissues) is actually a combination of root and stem (the top of a carrot, for example, is actually derived from stem tissue merging with the root tissue below).
Okay, geek speak over, but let me start with the ethno-botany speak, which is decidedly cool and not geeky. Sweet potatoes are originally from the tropics, but many varieties have been bred here in the States, even in this region. The Nanosecond and its sub variety Hanover are from Virginia, and the Hayman is a white variety from the Eastern Shore. Most of this year’s crop are Beauregard and Covington, beautiful orange roots. We also have smaller amounts of white- and cream-colored sweets, called All Gold, Jersey White and White Hayman. You’ll taste a difference – the whites often take longer to grow, have drier skin, and a distinct, less sweet taste.
With our tropical summers, the Mid-Atlantic is a very good part of the country to grow these plants. They have sprawling vines and in some parts of the world are selected for their leaves rather than their roots. You may remember receiving sweet potato leaves at times in summer. Sweet potatoes also produce beautiful, morning glory-like flowers, though anecdotally they rarely if ever flower in the north. They are a crop that likes it warm – even in storage. If they get too cold during storage they will rot. Keeping them around 55°-65° should do the trick, and they can keep through winter and into spring.
Though it’s possible to grow sweet potatoes from other sweet potatoes, usually root sprouts or “slips” are planted. We treat our crop as an annual, but if you’d like to try to save “seed” or at least save money on slips, it’s possible to “perennialize” them in a way – especially since sweet potatoes are perennials in the tropics. In Heirloom Vegetable Gardening, William Woys Weaver offers a neat trick on how he maintains his crop: “My seed potatoes are planted in Styrofoam ice chests, and from the vines I root slips for my spring plantings. By growing the mother plants as perennials, I preserve plant purity and avoid the worry of losing seed stock of the winter. Furthermore, the leaves of sweet potatoes are entirely edible [though of course we already knew that] and can be cooked like spinach greens. Therefore, by pruning my vines, I not only have a supply of greens over the winter, I also encourage the vines to branch and produce more bootable shoots.” Another advantage to this method is that it reduces risk of pest problems that can be transmitted through infected tubers or shoots.
And then you get to eat them. They’re savory and they’re sweet. With a large amount of Vitamins A and B6, beta-carotene and a whole host of other goodies, this makes one of the healthiest desserts around. Often I just pop a sweet potatoes in the oven (with several fork-stabbings throughout the thing) and let it cook while I eat dinner. You can put in the microwave but I like the oven, low and slow. You’ll smell it when it’s done. Once you can easily pass a fork through the skin and flesh, it’s ready to serve your sweet tooth.
I’m a huge fan of adding butter (and – hey – Vitamin A is fat soluble) but even plain or with olive oil they are excellent. Make sweet potato bread, muffins, and pie, mash them up, bake them, roast them, make them into fries and serve with garlic aioli – whatever you like. And remember, just because they go real good with maple things they don’t have to just be for dessert. Sub them in for potatoes to any part of your diet – put them next to salmon; try a salad with sweet potatoes, apples and apple cider vinegar; grill and glaze them with soy-sauce glaze… whatever you do, let us know how you decide to cook them. We love sweet potato recipes.
This year we have some mammoths and this will take some kitchen agility to work with. Large sweet potatoes are easier to grate, cube, and julienne, so consider trying recipes other than baking whole: roast with other root veggies (this week’s beets, last week’s turnips) or winter squash; mash them, or cut finely and use for raw salads .