The large, trumpet-shaped flowers commonly sold as Amaryllis are actually members of the genus Hippeastrum. This popular houseplant, native to the tropical and subtropical regions of Central and South America, requires light, but its needs are dynamic, shifting dramatically across its annual growth cycle. Successfully cultivating this bulb to achieve reblooming means managing the light intensity it receives during its active growth period and its subsequent period of rest. The Amaryllis needs sun, though the necessary light varies from bright exposure to complete darkness throughout the year.
The Ideal Light for Active Growth
During the period when the Amaryllis is actively growing—producing its flower stalk or its long, strap-like leaves—it requires abundant light to store energy for the next bloom cycle. The plant thrives in bright, filtered sunlight, which mimics its natural environment of dappled light beneath a tree canopy. A location that receives at least four to six hours of bright light daily is ideal for robust foliage growth after the initial bloom has faded.
Insufficient light results in a weak bulb that lacks the necessary reserves to flower the following year. Too little light also causes etiolation, where the flower stalk or leaves stretch excessively toward the nearest light source, becoming pale and structurally weak. Conversely, placing the Amaryllis in intense, unfiltered direct sun can scorch the foliage, leading to brown or crispy edges.
The best light during the active growing phase is bright, indirect exposure, which provides high light levels without the intense heat of midday sun. After the initial bloom, the primary goal is to maximize the energy the leaves can capture to fatten the bulb. This vegetative growth phase requires the most sustained light exposure, often extending from late winter through early fall.
Managing Light During the Dormancy Phase
To reliably rebloom, the Amaryllis bulb must undergo a necessary period of rest, or dormancy, which typically lasts between eight to twelve weeks. This resting phase is initiated by withholding water and fertilizer, signaling to the plant that its growing season has concluded. Once the foliage naturally begins to yellow and die back, it should be cut away, and the bulb prepared for its dark retreat.
During this 60-to-90-day rest period, the bulb requires total darkness or near-darkness, combined with cool temperatures, ideally around 50 to 55°F. The absence of light is a crucial environmental cue that triggers the internal hormonal changes required for flower bud formation within the bulb. Storing the potted bulb in a dark, cool basement, closet, or unheated garage is the simplest way to meet this requirement.
Exposure to light during dormancy can confuse the bulb, potentially causing it to break its rest prematurely and produce weak, untimely leaf growth instead of preparing a bloom stalk. This cool, dark period ensures the bulb’s internal chemistry is reset, preparing it to break dormancy and send up a flower stalk when it is reintroduced to warmth and moisture.
Choosing the Best Location for Your Amaryllis
Selecting the right spot for an actively growing Amaryllis means strategically utilizing available light based on the season and the plant’s current phase. During the critical energy-storing phase, a south-facing window is often the best choice because it provides the longest duration of bright light throughout the day. However, this intense light may need to be diffused with a sheer curtain to prevent scorching during the hottest summer months.
East-facing windows, which offer bright morning sun, or west-facing windows, which provide intense afternoon light, are also excellent locations for the Amaryllis. Once the flower stalk has emerged, the plant should be rotated by a quarter turn every few days to ensure the stem grows straight and does not lean toward the light source. This simple action prevents the flower stalk from becoming top-heavy and bending under the weight of its large blooms.
Temperature also plays a role in placement. While the bulb needs warm temperatures (70–75°F) to encourage initial growth, moving the plant to a cooler location (around 65°F) once the flower buds show color will prolong the life of the open blooms. The plant should be kept away from cold drafts from exterior doors or excessive heat from radiators, which can stress the plant and shorten its flowering period.