|Meyer lemon (Citrus × meyeri) plants survive|
Piedmont winters better indoors.
NC Extension Master Gardener
As temperatures cool and frost approaches, it is time to bring houseplants indoors for winter. Most houseplants are of tropical origin and can suffer damage at temperatures well above freezing. Many houseplants can sustain damage at temperatures below 45°F, while some can be damaged when temperatures fall below 50°F. This is a good rule to follow: Whenever nighttime temperatures begin to fall below 50°F, it is time to bring your houseplants indoors.
Most houseplants perform best if they are allowed to gradually acclimate to their new indoor environment. Otherwise they are likely to lose lots of leaves within a few days of being moved indoors. While this is usually not life threatening, it does set the plants back by a few weeks. Avoid excessive leaf loss by making the change less traumatic. If outdoor plants have been in a high light environment, place them in a similar environment indoors: near south-facing windows or under plant lights on a timer. Be sure to clean windows to allow maximum light penetration.
Prior to bringing plants indoors, inspect leaves and stems for insects and diseases and treat appropriately. Soaking the pots in lukewarm water for about 15 minutes can force some insects out of the soil. This is also a good time to re-pot, if necessary. To determine what size container is needed, measure the height of the plant and divide by two. This should be the diameter of the pot used for the plant.
To keep plants healthy during winter, do not overwater. Allow the surface of the potting soil to become dry to the touch between waterings. Most houseplants require very little to no fertilizer over winter because this is a time of reduced growth. Giving plants just the bare essentials over winter is the best approach.