Even kids revel in watching the dormant amaryllis (Hippeastrum spp.) bulb awaken and flower indoors as part of a holiday gift box, buy if you garden in U.S. Department of Agriculture (USDA) hardiness zones 8 and warmer, you can plant amaryllis bulbs outdoors and watch them proliferate into handsome clumps in the perennial border. They also grow nicely in large containers.
Locate a prime location in the garden for the amaryllis. It should receive 5 to 8 hours of sunlight daily, but occasional shade from nearby buildings or trees is great. In subtropical climates with hot summers, bright shade in the early afternoon is necessary. Too much hot sun increases water needs and scalds and prematurely browns foliage. Excessive sun exposure also shortens the life span of the flowers.
Check the soil quality. Amaryllis needs to grow in a well-draining soil that is moist from spring to fall when leaves grow. Where copious summer rainfalls occur, provide an exceptionally well-draining soil with coarse grit incorporated among organic matter. Although tolerant of slightly acidic soils, a soil with a pH of 6.5 to 8.0 is ideal.
Plant the large baseball-sized amaryllis bulbs when dormant or when the strappy leaves begin to yellow and the flower stalk is no longer present. Dig a hole the same size and depth as the entire bulb with a small shovel or garden trowel.
Place some bone meal and compost in the planting hole bottom and mix it together. Also add and mix a little compost into the soil destined to refill the planting hole.
Position the pointed tip of the bulb upwards and cover the bulb with soil, exposing 1 to 2 inches of the bulb's neck and tip. Add soil to the hole as needed, making sure no less than 1 inch of the neck or tip of the bulb remains above the soil surface. In sandy soils plant the bulbs slightly deeper so that the bulb tip is just above the soil line.
Water the bulbs so that the soil comes in contact with the bulb and air pockets are removed. When leaves are present--anytime from spring to fall--water freely so soil is moist but never soggy.
Fertilize the plant with a liquid fertilizer (20-20-20), spraying it on the foliage and the surrounding soil every four weeks across spring to early autumn. Follow product label directions for dosage.
Allow the foliage to grow unharmed. In mid- to late autumn, the leaves naturally wane, turning yellow. In mild winter regions, sometimes the foliage remains. Reduce watering and halt all fertilizing from mid-autumn onwards. In rainy winter regions, place a thick layer of course leaf mulch atop the bulbs to help create a cooler, drier soil environment.
Monitor the planting in late winter and early spring, watching for the first hints of either new leaves or a flower stalk emerging from the bulb tips. Consider keeping the mulch over the bulbs until threat of frost ends in USDA zones 8 and 9.
Resume light watering of the soil around the amaryllis bulbs once leaves or the flower stalk emerges. Do not over water, but keep soil moist. After the flower stalk produces its blossoms and withers, begin the watering and fertilizer regimen again to promote lush foliage. Additional flower stalks may appear in early to midsummer, even while leaves grow and you continue fertilizing.