Getting to the root of it: Root veggies grow well during winter months

With the current chill in the air, I started thinking about planting more root vegetables. They grow well in our cool winter months and are delicious singly both hot and cold or combined as ingredients in soups and stews.

Think carrots, beets, turnips, radish and daikon for starters. You can even venture into rutabagas and parsnips if you like. Onions and other members of the Allium family are also good root crops to consider. Following the traditions of ancient Hawaiians, you might also want to include some taro, yams and sweet potatoes in your garden.

The Solanum tuberosum potato is another root crop native to South America but popularized in North America by early European settlers. A future article will consider the many varieties of these potatoes that we can grow here in Hawaii.

Jicama is also considered a root crop. It has thick, brown skin with a crisp white interior that tastes a bit like an apple but less sweet. Check out growing information online if you want to cultivate jicama.

Many root vegetables were staples in the diet of ancient Greeks and Romans. They were also cultivated in Asia for centuries. Roots continued to be a dependable winter food source in Europe during the Middle Ages. Early colonists brought root vegetables to the Americas and by 1900 many had become an integral part of the American diet. Missionaries and other colonists from the U.S. brought their favorite root vegetables to Hawaii as early as 1850.

The Polynesians voyagers brought taro, yams and sweet potatoes to Hawaii long before European root vegetables arrived. These, as well as the more recently introduced vegetables, can offer a wonderful addition to our Kona gardens as well as to our dinner plates.

Root vegetables are a healthy addition to our diet. They supply vitamins and minerals as well as carbohydrates and fiber. They have fewer calories than grains while adding vibrant colors, textures and flavors to a meal. In addition to their health benefits, root vegetable plants offer aesthetic appeal to the garden. Most have leaves that are not only edible but can also serve as attractive border plants

Probably the easiest root crop to grow is Raphanus sativus, the common radish. They are best grown from seeds that germinate quickly. Some varieties mature in less than a month, producing small flavor-packed globes with a multitude of uses. Pick them when the roots are crisp and the flavor is at its peak. Red, white and black species vary in flavor from sweet to hot. Mild French varieties make a tasty sandwich on a baguette with sweet butter.

Raphanus sativus var. longipinnatus, is an Asian variety known as daikon. This tasty root can be served fresh, grated or pickled as well as cooked. Daikon roots can grow to over a foot long in the more than two months they take to mature.

Lots of carrot varieties are suitable for Hawaiian gardens. Daucus carota var. sativus is a cultivated form of a wild carrot known as Queen Anne’s Lace. Cultivation has produced a larger, sweeter and more colorful root with the same lacy tops that make carrots an attractive edging plant. Seeds are available in many varieties including White Satin, Purple Haze and Atomic Red. For rocky soils you may want to choose the shorter Thumbelina or Short n Sweet. Chantenay varieties can grow to 6 inches long.

Beta vulgaris is actually a biennial herb native to Europe and North Africa. Closely related to chard, beets were cultivated for their roots while chard developed the colorful, tasty tops. Most beet varieties also have delicious and nutritious greens. The popular Detroit Dark Red is a variety that dates from the late 1800s and produces deep colored roots and dark green foliage. Another older variety Chioggia was developed in Italy with rings of white, pink and red in each root. Newer varieties feature gold and white roots. The German Lutz was recently recommended to me for its large and tasty roots.

Turnips, Brassica rapa, are native to Russia and Scandinavia but can thrive in our cooler upland locales. All varieties are easy to grow, have sweet tasting roots and produce delicious greens that can be stir fried or steamed. Several colors are available including Golden Ball and Purple Top. Tokyo Cross is one of my favorites. It has a small root, is pure white, delicious and does very well here.

The heritage turnip Gilfeather is actually a rutabaga, has a longer growing season and produces a large root. If you live at an upper elevation and like a sweet turnip flavor, the rutabaga (Brassica napus) is a good choice. Rutabagas have a growing season of nearly three months and can be left in the ground even longer. They can survive frost and actually become sweeter when exposed to temperatures below 40 degrees.

Parsnips also sweeten over time in the ground. Their seeds can take three weeks to germinate and the roots may take three months to mature. Their unique flavor makes them worth the wait, however. They taste like a denser, sweeter carrot.

These carrots, beets, turnips, rutabagas and parsnips are all best grown from seeds planted directly in the garden. They should all germinate in less than a month and produce mature roots in two to three months. If you want to leave them in the soil once mature, it’s best to cover the tops of the roots to protect them from sun exposure.

Onions, leeks, chives and green onions or scallions are all easy to grow and will flower and seed in a single season. Save your seeds and replant for a continuous supply of these attractive and tasty Allium family plants. Garlic and shallots need very long hot summer days and are harder to grow here.

The plant Ipomea batatas is known as the Hawaiian sweet potato or uala. Though it is actually native to parts of South America, its tuber has been a staple in the Hawaiian diet for centuries. Hawaiians were cultivating it here when Captain Cook arrived in 1778 though when and how it arrived in Hawaii is not known.

Uala plants are propagated from cuttings and can tolerate full hot sun as well as partial shade. They are easy to maintain and produce delicious tubers as well as tasty shoots. Several varieties exist; each with leaves of a different shape and color. All make attractive ground cover plants

The native Hawaiian yam (Dioscorea alata) is known as uhi. It has a vining growth habit well suited to being a ground cover or a climber. The tubers can take up to a year to mature but are very tasty either boiled, baked, fried or mashed.

Taro root is, of course, well known here in Hawaii. A staple food in the Hawaiian diet, it is grown from huli, which are the stems of the tuber. The plants, known as kalo produce large heart shaped leaves that are also edible. Though kalo roots can take a year or more to fully mature, the plant is a stunning addition to any tropical garden.

When harvested, taro plants provide tasty leaves and tubers. Both need long cooking times to remove the oxalic acid. Taro is a versatile vegetable that can be served like a potato as fried slices or in a salad or even cooked in coconut milk. Mash taro root to make poi as part of a luau and you’ll be helping preserve an important native Hawaiian plant.

All of these root plants can be successfully grown here, though many will not likely produce flowers or seeds unless allowed to grow for a second year. These will grow best from purchased seed, planted directly in the desired location. Shallow sowing of the seeds encourages successful germination. The Hawaiian root vegetables are best propagated vegetatively.

Once the tops of the roots begin to protrude above the soil, the crops are ready to harvest. Most root crops can remain in the soil if it is cool and a little moist. Long-term storage in a cool root cellar or refrigerator is also possible after the leaves are removed.

Root vegetables do well in cool temperatures, making them ideal winter crops. At lower elevations or hot locations, consider planting them in partial shade. They will do best in slightly acid soil that has been deeply worked and is friable.

Water judiciously to keep the soil moist and avoid problems. Wet or soggy soil can cause root rot. Hot, dry soil can cause pithy roots. To encourage root growth, apply fertilizers with phosphorus and potassium numbers greater than nitrogen. High nitrogen fertilizers will encourage leaf rather than root growth. Beyond this, root plants need little maintenance and are rarely attacked by diseases or insects.

Root vegetables grown in cool locations in well-prepared soil and with adequate water will likely be healthy. In the rare case of insect or disease problems get a diagnosis and treat with organic products.

Recipes for root crops abound. They are wonderful in soups, chopped or grated in a stir-fry or fresh in a salad. Oven roasting brings out all the sweet, savory flavor of these nutritious veggies and can provide a nearly complete meal.

You may want to consider planting some root crops while the weather is cool. They will add beauty to your garden while providing delicious and nutritious ingredients for many meals.

Diana Duff is a plant adviser, educator and consultant living part time in Kailua-Kona

Gardening Events

Saturdays: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Come with a mask and prepared to practice social distancing. Volunteers can help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Visit the website www.amygreenwell.garden/get-involved/volunteer-1/ and sign up for the weekly email for more information on work days.

Monday, Feb. 6: “USDA Grant Info Session” on Rural Energy for America Program &Value Added Producer Grant from noon to 1:30 p.m. at the West Hawai’i Civic Center Community Meeting Hale 74-5044 Ane Keohokalole Highway. An in-person event.

Saturday, Feb. 11: “16th annual Avocado Festival” from 10 a.m. to 4 p.m. at Hale Halawai in downtown Kailua-Kona. Booth space still available. Forms available at https://hawaiianwellness.com/upcoming-events. More information available by calling or texting Randyl Rupar at (808) 936-5233 or e mail at randyldna@earthlink.net

Thursday, Feb. 23: UH CTAHR Forum “Indigenous Food Systems” 12 to 1:30 p.m. on Zoom. For more info or to get zoom link email: sothy@hawaii.edu.

Friday, Feb. 24: “Kona Coffee Farmers Association Symposium” from 9 a.m. to 4 p.m. in the Bayview Room at the Outrigger Kona Resort &Spa in Kailua-Kona. Free parking. Includes topics pertaining to coffee growers, including soil health and ways to increase profitability. Free to KCFA members. $40 includes lunch for nonmembers. Register at https://konacoffeefarmers.org/product/2023-annual-conference-registration/. For more information, contact Conference Committee Chair, Carolyn Witcover at (808) 640-1647 or carolyn54@gmail.com.

Saturday, Feb. 25: “Grow Hawaiian Festival 2023” at the Amy B.H. Greenwell Ethnobotanical Garden. Go to amygreenwell.garden or contact Kim Kahoonei at kimkahoonei@amygreenwell.garden for more information

Tuesdays in February and early March: “Coffee Leaf Rust Research and Management Update Webinars” starting at 9 a.m. with pre-recorded presentations for 20-25 minutes each. Followed by live Q&A session for about 35-45 minutes. Presenters from USDA ARS PBARC, HARC, and UH-CTAHR will share information and updates about CLR research projects, field trials, and disease management. Registration is required to receive the Zoom link. Contact Matt at (808) 322-0164 to register at least 2 days prior to the event. Contact Andrea at andreak@hawaii.edu, (808) 322-4892 or (415) 604-1511 (text OK) for more information.

Plant Advice Lines

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