Will amaranth come back every year depends on the type and your climate. Most amaranth plants die at the first hard frost in fall. But they often drop seeds that sprout on their own next spring. In warm zones, some types live on as short-lived perennials.
Both grain amaranth and globe amaranth fall into the group of self-seeding flowers. The plants drop hundreds of small seeds each fall. Some of these seeds sprout the next year if the soil is warm and bare. You can get new plants for free with no work at all.
In my own yard, I have watched globe amaranth come back for five years in a row. I leave the spent plants in the bed all winter. New seedlings show up in late May or June when the soil warms up. Some years I get more volunteers than I planted the first time.
Amaranth plants are reseeding annuals in most U.S. zones. This means they live for just one season but leave seeds behind. The parent plant dies but the next year brings fresh seedlings on its own. You only need to plant once if your beds stay undisturbed.
In zones 9 to 11, globe amaranth acts as a tender perennial instead. Plants live for two to four years if frost stays away. They keep blooming each summer with a short rest in winter. Heavy frost will still kill the tops fast even in mild zones.
The full amaranth lifecycle runs about one growing season. Seeds sprout in spring when soil hits 65°F (18°C). Plants grow tall and bloom by midsummer. Flowers fade and form seed heads by fall. Frost kills the plant but seeds stay viable in the soil.
Globe amaranth seeds stay viable for one to two years in your soil. Some may sprout in year one, others wait for year two. This means you can get blooms for a few years from just one round of seeds. Skip the seed packet purchase if your plants self-seed well.
Volunteers sprout when ground temps hit 65°F (18°C) and stay there. This means late May in zone 5 and early April in zone 9. Mark the spots in your bed where you grew plants last year. You can spot the seedlings as they pop up and avoid pulling them by mistake.
Young seedlings look like tiny pairs of green leaves. They grow slow at first, so be patient with them. Within four weeks, they will hit a few inches tall and start to look like the parent plant. Thin them to 8 inches apart for the best blooms.
To boost the odds of return blooms, leave some flowers on the plant in late fall. Skip the deadheading once cool weather hits. Let the heads dry on the stem and drop seeds on their own. This mimics how the plants spread in the wild for thousands of years.
Skip fall mulching on seed beds too. A thick layer of bark or straw can block seeds from soil contact. The seeds need to touch bare soil to sprout next year. Leave a few inches of bare ground around each plant for best results.
When you compare annual vs perennial flowers, amaranth is unique. It acts like a short-term perennial in warm zones. It acts like a reseeding annual in cold zones. Either way, you get fresh plants each year with very little work on your part.
If you want a sure return, save seeds yourself in fall. Cut a few dried heads from the best plants. Rub them between your hands over a paper bag. Store the seeds in a cool, dry spot until spring. This backup plan works even if your bed gets disturbed by mulch or tilling.
Some types reseed better than others in home gardens. QIS and Las Vegas mix lines are top picks for strong reseeding. Hybrid types like some Buddy varieties may not come back true to type. The new plants may look different from the parent if they sprout from hybrid seed.
Plant your amaranth in a permanent bed if you want long-term blooms with no work. Avoid tilling or deep digging in that spot each year. Light hand-weeding in spring keeps the bed clear without harming young seedlings. You can enjoy blooms for many years from one starting batch.
Read the full article: Globe Amaranth: Grow, Dry, and Design
