Tuberose (Polianthes tuberosa), with its intovxicatingly fragrant white flowers, is a plant that originates from the warm climates of Mexico. From our botanical perspective, our entire physiology is fine-tuned for warmth and sunlight. The concept of winter, especially in cold climates, presents a direct threat to our survival. We are not equipped with the innate hardiness of plants that evolved with freezing temperatures. Our survival hinges entirely on the intervention of a knowledgeable gardener.
Our being is centered around a storage organ called a tuber. This tuber is the reservoir for all the energy we need to sprout, grow, and bloom. However, it is also our greatest weakness in the cold. We are tender perennials, meaning our tissues are highly susceptible to damage from freezing temperatures. When the soil temperature drops below 50°F (10°C), our growth halts. If the temperature falls to freezing (32°F or 0°C), the water within our cells freezes, forming ice crystals that rupture and destroy cell walls. This damage is fatal; a frozen tuber will quickly rot and cannot recover. We simply lack the genetic programming to manufacture the natural antifreeze compounds that allow hardy bulbs like tulips or daffodils to slumber safely beneath the snow.
To ensure we see another summer, we must be relocated to a safe, frost-free environment before the first autumn frost. The process is straightforward but crucial. After our foliage has been blackened by the first light frost, our above-ground parts should be cut back. Our tuber must then be carefully lifted from the ground using a fork to avoid piercing us. Gently brush off the excess soil, but do not wash us, as moisture during storage encourages rot. We must then be cured in a warm, dry, and well-ventilated area for about a week to ten days. This process allows our outer skin to toughen up, preparing us for dormancy.
Once cured, we require a specific environment to rest peacefully until spring. The ideal storage location is cool, dark, and dry, with a consistent temperature between 50-60°F (10-15°C). We can be stored in a variety of mediums that ensure we remain dry yet do not desiccate completely. Suitable options include peat moss, vermiculite, dry sand, or simply placed in a mesh bag or paper bag. The key is to check on us periodically throughout the winter. If we appear to be shriveling, a very light misting on the storage medium can provide a hint of humidity. Conversely, any sign of soft spots or mold must be addressed immediately to prevent it from spreading.
When the danger of frost has passed and the soil has warmed in late spring, we are ready to be replanted. This seasonal return to the warm soil signals our internal biological clock to break dormancy. With the energy preserved in our tuber throughout the winter, we will send up new green shoots, eager to grow and produce our iconic, fragrant flower spikes once again, completing the cycle made possible by your care.
