Swiss Chard

What it is. Swiss chard (Beta vulgaris var. cicla) is a leafy green from the same species as beet, but it does not grow a swollen root. It is also called silverbeet and perpetual spinach. Its leaves are large and ruffled, with stalks in white, pink, gold, orange, or red depending on the variety. Because the stalks are so colorful, it also works in flower beds and containers as an ornamental edible.

Life cycle. Extension guides describe it as a biennial that is usually grown as an annual. Gardening experts profile lists both annual and biennial types within the leaf beet group.

When and how to sow. Sow seed directly in the garden in early spring or late summer. Gardening experts advise sowing once the soil reaches 40 °F (4 °C). Each seed is actually a small cluster with several embryos, so you will need to thin seedlings unless you buy monogerm seed.

Depth and germination. Plant seed about ½ inch (1.3 cm) deep and cover it with fine soil. Maryland also suggests 1 inch (2.5 cm) in sandy soil, and Wisconsin advises planting an inch deep. Seedlings emerge in 7 to 14 days, with the best germination at 55 to 75 °F (13 to 24 °C). Gardening experts report a wider range of 40 to 100 °F (5 to 38 °C), with the best at 86 °F (30 °C). Temperatures above 80 °F (27 °C) reduce germination.

Thinning and spacing. Thin seedlings to about 4 inches (10 cm) apart when they are about 2 inches (5 cm) tall. Other guides give wider final spacing: about 6 inches (15 cm) apart in rows 12 inches (30 cm) apart, or 8 to 12 inches (20 to 30 cm) apart for larger plants. Gardening experts suggest 4 to 6 inches (10 to 15 cm) apart for larger leaves.

Starting indoors. Seeds can be started indoors 5 to 6 weeks before transplanting. Transplants with 4 to 6 mature leaves usually take 5 to 6 weeks to grow. Gardening experts suggest transplanting about four weeks after starting seeds indoors.

Light and soil. Swiss chard grows in full sun to partial shade. Maryland says it grows best with 6 to 8 hours of direct sun and tolerates partial shade of 4 to 6 hours. It prefers fertile, well-drained soil rich in organic matter, with a pH of 6.0 to 8.0.

Containers. It grows well in containers, doing best in a pot at least 2 quarts (about 1.9 L) and 8 inches (20 cm) deep.

Watering. Keep the soil evenly moist and water deeply and regularly during dry spells. Gardening experts suggest 1 to 2 inches (2.5 to 5 cm) of water per week. Mulch helps conserve moisture and reduce weeds.

Feeding and weeds. Chard needs a high supply of nutrients from soil organic matter or fertilizer. Gardening experts suggest ¼ cup of 21-0-0 nitrogen fertilizer per 10 feet of row, placed beside the plants 4 weeks after transplanting or thinning. Swiss chard does not compete well with weeds, so pull young weeds by hand and keep plants closely spaced.

Pests and disease. Gardening experts list no significant problems for this plant group. Maryland lists bolting, Cercospora leaf spot, leafminer, and root knot nematodes. Root knot nematodes cause swollen galls on the roots. Wisconsin mentions aphids and leafminers, and says to remove any plants that bolt and any leaves with mines. Gardening experts add slugs and flea beetles, which can damage seedlings.

Harvesting. Pick the outer leaves first so the inner leaves keep growing. Gardening experts suggest harvesting outer leaves when they are 4 to 12 inches (10 to 30 cm) long. Baby leaves can be picked in roughly 30 days and mature leaves in about 60. Leaves smaller than 4 inches (10 cm) can be eaten raw in salads, while larger leaves are chopped and sautéed. To rejuvenate a plant, snip leaves about 2 inches (5 cm) above the crowns, and harvesting can continue until frost.

Storage. Chard is very perishable. Store it in the refrigerator in a vented mesh or plastic bag, in cold, humid conditions near 32 °F (0 °C) and 95% relative humidity. Gardening experts and Wisconsin both say it keeps for about 1 to 2 weeks in the refrigerator. Wisconsin notes it can also be frozen, dried, or canned.

Safety. Gardening experts list Swiss chard as non-toxic for cats and dogs. These are pet ratings only; the profile gives no toxicity rating for people. Maryland notes that all parts of the chard plant contain oxalic acid, which is not a toxicity rating for people or pets.