The Amaranthus genus is a complicated one, featuring at least 75 annual and perennial species that easily cross-breed and hybridize. Today, most gardeners are familiar with the species as ornamental plants, and many don't even realize that amaranths are also edible plants that can be grown for their grain-like seeds and edible leaves. In fact, this was once the primary reason amaranth served as a staple in home cottage gardens. Historically, the use of amaranth as an ornamental plant is a relatively recent development.
Edible amaranth is often grown for the plentiful tiny seeds that hang in tassels from the top of the plant after the attractive red flowers fade. The bulk seed is used as a "grain" in porridges or added as a thickener to soups and stews. The seeds are extremely nutritious and protein-packed, with a slightly nutty flavor. You can also use the leaves of amaranth as a leafy vegetable; the taste is similar to spinach and it can be used in the same way as many other leafy vegetables, especially in mixed-green salads.
If consumption is the goal, choose annual amaranth varieties marketed as edibles. Nearly all amaranths are edible, including love-lies-bleeding and even the common road-side weedy forms. But those sold as edible varieties are selected for their good seed production and especially tasty leaves.
Amaranth is native to North America and Central America, and is usually planted from seed as soon as the last frost has passed in the spring. If you are eager for early harvest, you can start the seeds indoors as much as eight weeks earlier. If you want to harvest the plants for seeds, it will take about 12 weeks for the plants to reach full maturity. Leaves can be harvested within a few weeks of outdoor planting.
|Common Names||Amaranth, amaranthus, pigweed|
|Plant Type||Herbaceous annual|
|Mature Size||2–5 ft. tall, 1-2 ft. wide|
|Sun Exposure||Full sun, partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Bloom Time||Summer, fall, early winter|
|Flower Color||Red, burgundy, pink, orange, green|
|Hardiness Zones||2-11 (USDA)|
|Native Area||North America, Central America|
Amaranth grows well in any average well-drained soil, and you should make sure the site you choose has good drainage and air circulation. To ensure continued production, it's a good idea to stagger planting every two to three weeks, beginning a week or two after the last frost date in your region.
While amaranth plants are tall, they aren’t necessarily wide or bushy, so you can get away with planting them 10 to 18 inches apart. The closer you can get them, the better they look once fully grown. At the same time, they need enough space to provide good air circulation.
Amaranth does best in full sun in the northern part of its range, but in warm southern climates, it can benefit from some shade in the afternoon. Generally, aim to give your plant at least six hours of sunlight a day.
Amaranth grows well in average soils and will even grow adequately in poor soils. Only dense clay mixtures are likely to be completely unsuitable for amaranth, though very rich soils may hinder flowering and seed production.
Amaranth plants have average needs for water, requiring no more than 1 inch per week. Take care not to overwater your plant, or you run the risk of root rot or fungal diseases.
Temperature and Humidity
Unlike other leafy green vegetables, amaranth is fairly happy in the heat. Many species are native to the southern U.S. and Mexico, so you can expect them to thrive even when the temperatures are unusually warm.
Amaranth doesn't require any additional feeding. In fact, excessive nitrogen (often found in fertilizers) can cause the plants to become leggy and less suitable for harvesting.
Varieties of amaranth can range from giants topping 8 feet tall, to smaller 1- to 2-foot plants better suited for leaf harvest only. You should cultivate larger plants specifically grown for their seeds if you want the amaranth grain. Some popular varieties include:
- Red-leaf amaranth (Amaranthus tricolor): This varietal has especially nutritious foliage that tastes like slightly tangy spinach. 'Molten Fire' and 'Joseph's Coat' are popular cultivars of this species.
- ‘Burgundy’ (A. hypochondriacus): Stunning purple leaves, red flowers, and white seeds adorn this varietal.
- ‘Hopi Red Dye’ (A. cruentus): An heirloom species, it produces excellent protein-rich black seeds.
Thanks to their plentiful seeds, amaranth plants will readily self-seed in the garden. As they sprout in spring, the volunteers can be thinned out to about 10 to 18 inches apart, or carefully dug up and transplanted elsewhere. It's also possible to collect some of the seeds in the fall and replant them the following spring. Be aware, though, that if the original plants were hybrids, the volunteer seedlings may not "come true" and can look different than the parent plant.
How to Grow Amaranth From Seed
When planting amaranth outdoors, sow seeds about 4 inches apart, barely covering them with soil. Germination generally takes seven to 14 days. As they sprout, thin the plants out to a spacing of 10 to 18 inches.
If starting seeds indoors, you can use a general seed-starting mix and make sure to harden off the seedlings before transplanting them outdoors. The average outdoor temperature needs to reach about 55 degrees Fahrenheit before you can successfully plant the seedlings outdoors.
You can harvest both the leaves and grains from any amaranth, but if your goal is an edible plant, choose a variety specialized for that. Some types of amaranth are marketed as best for seed production, while others are bred for their attractive, tasty leaves. Regardless of your cultivar, amaranth leaves can be harvested at any point. Small leaves are more tender, but the larger leaves boast a fuller flavor. Large size and heat won’t turn amaranth leaves bitter, as often occurs with other leafy greens, so you can harvest at any point throughout the season.
When harvesting the plant's leaves, make sure to leave the crown intact, as well as some leaves around the top, so the plant can continue to grow. Alternately, you can also cut the whole plant off at ground level when it is between 1 and 2 feet tall. It’s possible that it will resprout for another harvest, though you do risk introducing pests to the open stem.
To harvest amaranth grains, let the plant go all the way to flower. Keep an eye on the flowers as they bloom and begin to die back. Before they all turn brown, cut the flowers off and place them in bags, where they will dry. Shake the bag once they are dry, or knock the seeds loose over a cloth. Rinse away the dried seed “chaff” and enjoy your grain harvest. Amaranth is especially good in a porridge that also contains other grains, like millet and quinoa.
Amaranth can fall prey to many of the same pests and diseases that affect other vegetables. Aphids and flea beetles are common; insecticidal soaps are a good remedy for the former, and floating row covers will protect the plants from the latter. Avoid using commercial pesticides with a "wait to pick" or any other type of warning regarding consumption. Many of these types of pesticides are broad-spectrum, designed to eliminate multiple insects, and may contain ingredients that aren't meant to be ingested by humans.
Root rot can also be a problem in wet, dense soil or in periods where rainfalls are frequent and copious. Once root rot occurs, the plant must be removed. Your best defense against the issue is maintaining well-draining soil and not overwatering the plant.