As the days shorten and temperatures drop, we, the petunias, receive a clear environmental signal. Our summer-long cycle of vigorous vegetative growth and prolific flowering must come to an end. The reduced light levels tell us that it is no longer efficient to support our expansive form. In response, we begin to slow our metabolic processes. This is the ideal time for you to intervene. Bringing us indoors before the first frost is critical, as freezing temperatures will cause irreversible cellular damage, leading to our demise.
The move from the outdoor garden to your home is a significant shock to our system. To minimize this stress, please prepare us gradually. About two weeks before the intended move, prune our stems back by roughly one-half to two-thirds. This drastic haircut is not an attack on our beauty! It is a necessary step to reduce our overall leaf mass, which will minimize water loss (transpiration) and make it easier for our root systems to sustain us in lower-light conditions. Simultaneously, check our foliage and soil meticulously for any signs of pests like aphids or whiteflies. An infestation brought indoors can quickly spread to your other houseplants.
Once indoors, our survival depends on replicating, as much as possible, our preferred dormant conditions. We crave bright, direct light. A south-facing window is ideal for us. Without a minimum of 6 hours of strong light, we will become etiolated—stretching out with weak, pale stems and sparse foliage in a desperate search for the sun. The temperature is equally important. We prefer a cool and bright dormancy. A consistent temperature between 55-65°F (13-18°C) is perfect. Avoid placing us near heat vents or radiators, as excessive dry heat will desiccate us and confuse our natural cycles. Water is our lifeline, but our needs are now minimal. Please allow our soil to dry out almost completely between waterings. The cooler temperatures and reduced growth mean we use very little water. Soggy, cold soil will quickly lead to root rot, which is often fatal.
Do not expect flowers or new growth during this period. To you, we may appear to be merely surviving—and that is exactly the goal. We are in a state of dormancy, conserving our energy and resources within our roots and main stems. Our metabolism is slowed to a bare minimum. This is not a time for fertilizer, which would force us into a weak, spindly growth spurt that we cannot support with the available light. Our only request is for you to occasionally remove any yellowing leaves that may appear, which helps prevent fungal diseases.
As winter wanes and the sun strengthens in early spring, you will notice signs of new life from us. Tiny green buds will appear along our stems. This is our signal that we are ready to break dormancy. This is the time for a gentle pruning to shape us and encourage bushier growth. You can begin to increase watering frequency slightly. However, hold off on fertilizing and do not move us back outside until all danger of frost has passed and nighttime temperatures are consistently above 50°F (10°C). A gradual re-acclimatization to the outdoors over a week is essential to prevent sunscald on our tender new leaves.
