How to grow Amaranth

Where to plant

Amaranth is a warm season annual that grows best at about 70 to 85°F (21 to 29°C) and tolerates heat up to about 110°F (43°C). Temperatures below about 40°F (4°C) injure it and frost kills it. Grow it in full sun in well drained, reasonably fertile soil. It copes with a wide pH range, from about 4.3 to 8, but grows best between 5.5 and 7.

Sow it after the last frost once the soil has warmed. In Florida, UF/IFAS gives the earliest planting as May in North Florida, April in Central Florida and December to February in South Florida, and it then grows through the summer. Across the rest of the country, sow from May to early summer, once the soil is warm. In wet summers, a raised bed keeps the roots out of standing water.

Choosing a variety

Vegetable amaranths, mainly Amaranthus tricolor and related species, are grown for leaves. They come in green, red and variegated forms, such as Red Garnet and Tiger Stripe, and Green Callaloo is a Caribbean favorite. Tampala is a variety UF/IFAS notes as suited to the southern US. Grain amaranths (A. caudatus, A. cruentus and A. hypochondriacus) are taller, with large plumes of seed, and their young leaves can be eaten as well.

How to plant

1. Wait until after the last frost and until the soil reaches about 70°F (21°C). Seed sown in soil colder than about 50°F (10°C) germinates slowly or not at all.
2. Sow the tiny seed about one eighth to one quarter of an inch (3 to 6 mm) deep, about an inch apart in rows 12 to 18 inches (30 to 45 cm) apart, or scatter it over a bed.
3. Keep the soil moist. Seedlings appear in about a week in warm soil.
4. Thin to about 6 inches (15 cm) apart for greens, and eat the thinnings as microgreens. Grain types need more room.
5. If you transplant, do it while the seedlings are small. Late transplanting can make them flower early.

Watering and feeding

Amaranth is moderately drought tolerant, but a severe shortage of water makes it flower early and cuts the leaf yield. Water evenly to keep the soil moderately moist, especially while the plants are young, and do not let water stand around the roots, which brings on rot.

Go easy on fertilizer. UF/IFAS notes that feeding has not been shown to raise yields much, and too much nitrogen gives pale leaves and can build up nitrate in them. Compost dug in before sowing is enough for most garden soils.

Pruning and care through the year

• Grain types can reach 5 feet or more and may need staking in windy spots.
• Pinch out flower buds on greens types to keep leaves coming. Once plants flower, the leaves become fewer and tougher.
• Space plants well and keep water off the leaves to reduce wet rot, the main disease in humid summers.
• Pull plants before they drop seed if you do not want seedlings everywhere next year.

Harvesting

Vegetable amaranth greens are ready from about 3 to 6 weeks after sowing. Either pull whole young plants in one go, or cut the leaves and tender tips and let the plant regrow for another cut about two weeks later. Young leaves are the most tender; older ones turn coarse. The leaves wilt fast, so pick in the cool of the morning and refrigerate them straight away.

Grain amaranth is ready about three months after sowing, when the seed heads are dry and the seed falls out when you rub the head. Cut the heads, dry them further on a sheet, rub out the seed and winnow off the chaff.

Growing in pots

Greens types grow well in a pot at least 10 inches (25 cm) wide and deep with a good potting mix. Keep it in full sun and water often in hot weather, since a pot that dries out makes the plants flower early.

Using it

Young leaves taste mild, like spinach, and can be eaten raw in salads or cooked in stir fries, soups and stews such as callaloo. The leaves contain oxalates and nitrates, which cooking reduces, so cook them if you eat a lot. Grain amaranth seed can be cooked like a porridge, popped in a dry pan like tiny popcorn, or ground into flour.