During its primary growth period, which typically follows its bloom and extends through spring and summer, the amaryllis plant is focused on photosynthesis and energy storage. For optimal leaf and root development, a consistent temperature range of 68°F to 75°F (20°C to 24°C) is ideal. At this warmth, metabolic processes are highly efficient. The plant can readily absorb water and nutrients through its roots, converting sunlight into energy to produce long, sturdy, strap-like leaves. These leaves are the powerhouses that recharge the bulb, storing energy for the next flowering cycle. Temperatures significantly below this range will slow growth to a crawl, while excessive heat (constantly above 80°F/27°C) can cause stress, leading to wilted, weak foliage and potentially hindering the bulb's ability to store energy effectively.
To trigger the magnificent bloom for which it is famous, the amaryllis bulb requires a period of cooler dormancy, followed by specific thermal cues. After its summer growth, the bulb must enter a rest period. This is initiated by withholding water and placing the dormant bulb in a cool, dark environment with temperatures between 50°F and 55°F (10°C to 13°C) for a minimum of 8 to 10 weeks. This cool period is non-negotiable; it is a physiological requirement that allows the bulb to reset and develop the flower bud within. Once the rest period is complete and a new flower stalk begins to emerge, the plant should be moved to a warmer location. For the actual flowering stage, slightly cooler room temperatures of 65°F to 70°F (18°C to 21°C) are perfect. This moderate warmth encourages a strong, upright stalk and prolongs the life of the individual blossoms, allowing you to enjoy them for several weeks. Excessively warm rooms will cause the stalk to grow rapidly, often becoming leggy and prone to toppling, and will significantly shorten the bloom time.
Dormancy is not a sign of a sick plant but a critical part of the amaryllis's natural life cycle, mandated by its evolutionary background. This phase is essential for long-term vitality and ensuring re-blooming. The temperature during this period is arguably the most important factor for future success. The bulb must be stored in a cool, dry, and dark place, such as a basement or a cool closet, where temperatures are reliably maintained between 50°F and 55°F (10°C to 13°C). This sustained cool temperature prevents the bulb from breaking dormancy prematurely and depleting its energy reserves. It also ensures the proper physiological development of the embryonic flower bud inside the bulb. Storing a dormant bulb at regular room temperatures will prevent it from getting the rest it needs, leading to a failure to bloom the following season, or producing only leaves without flowers.
