The Jerusalem artichoke, or sunchoke, is the edible tuber of the plant Helianthus tuberosus, a species of sunflower native to North America. Despite its misleading name, it is not a true artichoke and has no connection to Jerusalem, with its common name likely evolving from the Italian word girasole, meaning sunflower. This hardy perennial is cultivated for its knobby, sweet, and nutty-flavored root, offering a culinary alternative to potatoes. The tubers are notably rich in inulin, a prebiotic fiber that the human body converts to fructose instead of glucose, making it a unique root vegetable choice.
Selecting the Right Location and Soil Preparation
Jerusalem artichokes perform best in a site that receives full sun, which means at least six hours of direct sunlight daily, though they can tolerate partial shade with a likely reduction in tuber yield. The plant is highly adaptable but thrives in well-draining, moderately fertile soil that is kept consistently moist. Waterlogged conditions must be avoided, as the tubers can rot easily in overly saturated ground.
Before planting, the chosen area benefits from thorough preparation, including removing all weeds and grasses. Tilling the soil to a depth of about 12 inches allows for better tuber development and makes the subsequent harvest easier. Incorporating organic matter, such as well-rotted compost or manure, will improve soil structure and provide initial nutrients for a robust crop.
Careful spatial planning is necessary because Helianthus tuberosus plants grow very tall, often reaching 6 to 10 feet in height. Due to their aggressive spreading habit through underground rhizomes, a dedicated, isolated bed is the best choice. Planting them along a fence line or on the north side of the garden can utilize their height as a natural windbreak or screen without shading other crops.
Planting and Initial Care
The optimal time to plant Jerusalem artichoke tubers is in the late winter or early spring, as soon as the soil becomes workable. Tubers are typically planted whole, but larger ones can be cut into pieces, ensuring each section has at least two to three “eyes,” or growth nodes, similar to planting potatoes. These tuber pieces should be planted about 4 to 6 inches deep to ensure proper anchorage and protection.
Spacings between tubers should be maintained at 12 to 18 inches apart within the row, with rows spaced at least 3 feet apart to allow for the plant’s mature height and vigorous growth. Once planted, the area needs a thorough initial watering to settle the soil around the tubers. Early-stage weed control is important until the tall, thick stems emerge and shade the ground, which will naturally suppress further weed growth.
Applying a layer of mulch, such as straw or grass clippings, after the shoots emerge helps to retain soil moisture and further reduces weed competition. The plant requires moderate and consistent moisture, especially during dry spells and the critical period of tuber formation in late summer.
Seasonal Maintenance and Controlling Spread
Throughout the summer growing season, Jerusalem artichokes are quite self-sufficient, demonstrating a good level of drought tolerance once established. While they can grow in poor soil, a side-dressing of compost or a balanced organic fertilizer can be applied in early summer to support the massive growth of stems and foliage. However, excessive nitrogen should be avoided, as it encourages leafy growth at the expense of tuber production.
As the sturdy, hollow stems grow rapidly, they can become vulnerable to strong winds. Staking or mounding soil around the base of the stems, a practice known as hilling, provides stability and prevents wind-rock, which can loosen the tubers in the ground. Cutting the tall stems back to about 5 feet in mid-to-late summer will encourage the plant to bush out and direct more energy toward the developing tubers underground.
The most important maintenance consideration is managing the plant’s aggressive spread, which occurs through its rapidly multiplying underground tubers and rhizomes. To prevent them from taking over the garden, a physical barrier is highly effective. This can involve planting them in large containers or using a dedicated raised bed with solid sides extending at least 18 inches below the soil line. For in-ground planting, a metal or heavy-duty plastic barrier sunk into the ground can contain the tubers’ lateral growth.
Harvesting, Storing, and Using Tubers
Harvesting should ideally begin in late fall, after the first few hard frosts have caused the tall, sunflower-like stalks to die back. This cold exposure is important because it converts the inulin within the tubers to fructose, which significantly sweetens their flavor. The tubers are typically ready for harvest about 130 to 150 days after planting, when the foliage turns yellow and withers.
To harvest, the dead stems should be cut down to a few inches above the soil line, and a digging fork should be used to gently loosen the soil in a wide circle around the plant base. Care must be taken to avoid puncturing the thin-skinned tubers, which are often clustered tightly around the main stem. It is crucial to collect every tuber piece.
The most effective storage method is to leave the tubers in the ground, harvesting them incrementally as needed throughout the winter. In regions with severe freezing, applying a thick layer of mulch will insulate the soil, allowing for easier digging during cold spells. For short-term indoor storage, unwashed tubers can be placed in a perforated plastic bag with a small amount of damp sand or peat moss and kept in a refrigerator or cool root cellar.