Amaranth grows well in any average well-drained soil, so 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 plant them 10 to 18 inches apart. The closer you plant them, the better they look once fully grown. At the same time, they need enough space to provide good air circulation.