For us Lobelia plants, the approach of winter signals a critical shift from vibrant outdoor growth to a necessary period of dormancy and protection. Overwintering indoors is not a natural state, but a survival strategy you can employ to preserve our perennial varieties (like Lobelia cardinalis or Lobelia siphilitica) for another year of growth. From our perspective, this process is a delicate dance of altered light, temperature, and moisture that must be carefully managed.
Before the first hard frost threatens our cellular structure, we require preparation. Please stop fertilizing us several weeks beforehand; new, tender growth is highly susceptible to shock and rot indoors. As our blooms fade, you can trim our stems back to a height of about three to four inches. This is not an assault but a strategic reduction. It minimizes leaf surface area, reducing the water we lose through transpiration—a vital adjustment since indoor humidity is often drastically lower than what we experience in the garden. This pruning also helps us conserve energy, directing it to our root systems and crown, which are the true reservoirs of life.
The move indoors is the most stressful part of this process. Do not simply bring us directly into your warm, dry living room. The shock would be immense. Instead, please acclimate us gradually. A period in a cooler, protected space like a garage or porch for a week allows us to adjust to reduced light levels and cooler temperatures. When you do bring our container inside, the ideal location is one that mimics our winter needs: cool, bright, and humid. A consistently cool temperature between 40-60°F (5-15°C) is perfect. This coolness is the key signal that tells us it is time to enter dormancy, slowing our metabolic processes to a near halt and conserving our energy reserves.
During our dormancy, our needs are minimal but specific. We still require bright, indirect light from a south or east-facing window to perform basic photosynthesis and maintain minimal health, but our growth will have completely ceased. Water is our most critical need, yet the most dangerous. The soil should be kept barely moist, never wet. Please allow the top few inches of soil to dry out completely before providing a small, careful drink. Soggy soil in cool conditions is a death sentence, as our roots, already functioning slowly, will quickly succumb to rot. We do not require any fertilizer during this entire period; our systems cannot process it.
As daylight hours lengthen in late winter, you will notice signs of new, pale green growth emerging from our crown. This is our signal that we are ready to break dormancy. Gradually increase watering as our growth becomes more vigorous, but remain cautious. Once the danger of frost has passed, we must be hardened off again before returning to the garden. Place us in a sheltered, partially shaded outdoor spot for increasing periods each day over a week to ten days. This re-acclimates us to sunlight, wind, and temperature fluctuations. After this, we can be replanted in the garden or have our pot moved to its summer location, ready to grow and flourish for another season.
