These plants can get BIG. If not pinching, plant plugs closely together in order to restrict their growth prevent them from getting enormous. If pinching, space them at 12" or more apart, and plan to pinch when the plants are about a foot tall to promote the development of multiple smaller side branches. For staggered summer blooms, consider planting mutliple successions of Amaranthus 3-4 weeks apart. Flea beetles are the primary pest, and might riddle the leaves with holes. But the leaves can easily be removed after harvesting.Liquid fertilizer is recommended while the plants are actively growing. However, applying too much nitrogen when the plants initiate bud will result in lots of vegetation but few flowers.