Q. My spring crop of Swiss chard started out fine, but when the plants got to be full size, about a third of them bolted. What caused some of my chard to go to seed, and how can I prevent future crops from bolting?
—H. Douglas, Overland Park, Kansas
A. The leafy vegetable known in the United States as Swiss chard is a productive, easy-to-grow crop worthy of a spot in the garden. Also called leaf beet or sea kale beet, Swiss chard originated in the Mediterranean region, not Switzerland, and its closest relations are beets and spinach rather than the artichoke-like cardoon from which the word chard derives.
Like most leafy garden crops, chard prefers cool temperatures, but it tolerates heat better than many greens. Chard will grow in full sun to partial shade and in any soil suitable for vegetable growing. You can start planting chard seed in the garden 1 to 2 weeks before the last frost date in your area, but hold off until after that date if you’re growing a red-stemmed variety, such as ‘Rhubarb’ chard, or a mix with red-stemmed chard in it. According to Cornell University’s online Vegetable Growing Guide, red-leaved chards may bolt if the seeds are exposed to freezing temperatures.
Because chard’s seeds are actually small fruits that contain multiple seeds, seedlings often germinate in clusters. Gradually thin young plants to a final spacing of 8 to 10 inches apart; use the thinnings in salads. Fertilize chard when the plants reach about 6 inches tall, side-dressing with alfalfa meal or watering with fish emulsion. Mulch to maintain even soil moisture during the growing season, and place a row cover over the crop at the first sign of leaf miners tunneling in the broad leaves.
If your chard bolts in the heat of summer, pull out those plants and sow seeds for a fall crop of these leafy greens. Choose a spot in partial shade for starting chard in the summer or provide light shade to help keep young seedlings cool.
Ask Organic Gardening is edited by Deb Martin
Originally published in Organic Gardening magazine, February/March 2014