Korean Chili Pepper

At a glance

Tip for beginners: Start seeds 8 weeks before your last frost on a heat mat, stake every plant at transplant, and in short-season areas count on green peppers as the main harvest, with red ones for drying as the late-season extra

Main challenge: Red peppers for gochugaru need a long, warm season; in short-season or humid areas much of the crop may stay green or develop anthracnose before it can be dried

When to plant

• Start seeds indoors 8 weeks before your last frost.
• Transplant outdoors 2 weeks after your last frost.
• First harvest about 10 weeks after transplanting.

What can go wrong

• Anthracnose. Sunken, round, water-soaked spots on ripening red fruit, later with rings of dark or orange spore masses. Worst in warm, wet weather and spread by splashing water. Remove spotted fruit, water at the base, mulch so fruit stays off the soil, and rotate away from peppers, tomatoes and eggplant for at least two years.
• Peppers still green at frost. The plant set fruit too late for it to ripen red. Usually a sign of a late start or a slow first month in cold soil. Start seeds on time, transplant into warm soil, and in short-season areas plan on green peppers as the main harvest.
• Purple leaf edges and stalled growth. Transplanted into soil that was too cold. The leaves darken or turn purple at the margins and the plant sits still for weeks. It is cold stress rather than a nutrient problem; the plant usually recovers once the soil warms.
• Snapped branches. Tall plants loaded with fruit split at the forks in wind or heavy rain. Stake each plant at transplant and run string along the row as the plants grow.
• Mold on drying peppers. Peppers dried whole in humid air can rot from the inside before they dry. Slit them lengthwise, dry in a dehydrator or a warm, airy spot, and discard any that turn soft or fuzzy inside.

Growing guide

Korean gardeners grow one pepper for two jobs. The same plant gives crisp green peppers through the summer, eaten raw with a dab of ssamjang, and then, if the season runs long enough, red peppers that get dried and ground into gochugaru. That second job is what makes gochu a long-season crop in most of the US. Green peppers can start about 10 weeks after transplanting. A real crop of red ones for drying usually takes several weeks more, and in a short-season garden the plants may still be loaded with green fruit when the first fall frost arrives.

Treat it like any other pepper, only with more patience. Start seeds indoors 8 weeks before your last frost, on a heat mat if you have one; the seed sprouts slowly in cool mix, and a soil temperature near 80°F tends to bring seedlings up in one to two weeks instead of three. Transplant 2 weeks after your last frost, once nights stay above 55°F and the soil feels warm to the hand. Peppers set into cold ground often stall and turn purplish at the leaf edges, and a plant that loses three weeks at the start rarely makes them up at the end. Space plants about 18 inches apart in full sun.

Korean peppers grow taller and more open than most bell peppers, and a branch heavy with fruit can snap in a summer storm. Korean farmers stake each plant and run string along both sides of the row as the plants grow, and that habit works well in a backyard bed too. Many also pinch off the side shoots below the first fork, where the first flower sits, so the plant puts its early growth into the main branches. Water deeply and evenly, mulch once the soil is warm, and go light on nitrogen.

In the US, seed for the milder all-purpose types turns up more often than seed for the hot ones. Kitazawa, now sold through True Leaf Market, carries several Korean hybrids, including Gochujang King for drying and Gochu Vita Green for eating fresh. Cheongyang-type peppers, the small sharp ones used in stews, are much hotter; seed for them sometimes turns up at Korean grocery stores and online Korean seed sellers. The disease to know is anthracnose: sunken, circular spots on ripening red fruit, often with rings of tiny dark or orange specks. It spreads by splashing water in warm, wet weather and can ruin a drying crop. Pick off spotted fruit, keep fruit off the soil, and keep peppers, tomatoes and eggplant out of that bed for at least two years.

For gochugaru, wait until the peppers are fully red on the plant and pick them before they soften. Korean farms traditionally dry them in the sun, which can work in dry Western summers but tends to mold in humid air. A dehydrator at about 125 to 135°F is the more dependable route in most of the country: wipe the peppers, slit them lengthwise so moisture can escape, and dry them until they snap instead of bend. Most cooks remove the stems and most of the seeds before grinding. At the end of the season, pick every full-sized pepper before your first fall frost; green ones keep a week or two in the refrigerator or can go into soy-pickled jangajji.

Harvest and keep