Lantana is a colorful tropical shrub widely cultivated as an annual in temperate climates due to its sensitivity to cold temperatures. Native to warmer regions, the plant cannot survive freezing conditions; even a light frost can cause significant damage. For gardeners outside of USDA Hardiness Zones 9 and above, overwintering lantana is the only way to ensure its survival and vibrant blooms the following season. Preserving the plant requires careful preparation and adherence to specific environmental conditions, whether aiming for dormancy or active indoor growth.
Pre-Winter Preparation
Preparing lantana for winter begins with timing its transition indoors, which should happen before the first hard frost. This is typically when nighttime temperatures consistently fall below 50°F (10°C). Bringing the plant inside too late risks cold shock and damage. Once indoors, a significant pruning is necessary to manage its size and focus the plant’s energy on root survival rather than foliage maintenance.
Cutting back the plant’s growth by about one-half to two-thirds is recommended to reduce water loss and the chance of disease. Before moving the plant indoors, a thorough inspection for pests is necessary to prevent an indoor infestation. Common outdoor pests like aphids, spider mites, or whiteflies multiply rapidly in the dry, stable environment of a home. Treating the plant with an insecticidal soap or a strong jet of water before moving it eliminates these unwanted guests.
Overwintering In-Ground
Gardeners in milder climates (USDA Zones 8 to 11) may leave lantana in the ground, as the root structure often survives a brief, light frost. In these transitional zones, the plant’s top growth will likely die back completely when temperatures dip below 28°F (-2°C), but the roots remain viable. This method requires severely cutting back the entire plant, leaving only a short stubble of stems about six to twelve inches above the ground.
Following the cutback, a thick, insulating layer of organic mulch must be applied over the root zone. A two- to four-inch layer of straw, shredded leaves, or wood chips stabilizes the soil temperature and provides protection against deep freezes. This covering shields the crown and roots from cold fluctuations, allowing the lantana to enter a period of root-hardy dormancy until spring. This technique is reliable only where winters feature intermittent, light freezes.
Method A: Keeping Lantana Dormant
Allowing lantana to go dormant is the most straightforward overwintering method for most gardeners in cold climates, especially if a bright indoor space is unavailable. Dormancy is induced by placing the potted plant in a cool, dark, and dry location, such as an unheated garage, basement, or cellar. The target temperature range is consistently between 40°F and 55°F (4°C to 13°C). Temperatures below this range risk freezing, and temperatures above it may prevent true dormancy, leading to leggy, weak growth.
In this cool environment, the plant’s metabolic processes slow down significantly, drastically reducing its need for water. The challenge is providing just enough moisture to prevent the root ball from drying out, while avoiding the waterlogging that causes root rot. Watering should be minimal, perhaps once a month, only when the soil feels completely dry several inches down. The plant may shed all its leaves, which is a normal sign of dormancy.
Method B: Growing Lantana Indoors
Gardeners who wish to maintain active growth or possess a bright indoor area can grow lantana as a houseplant throughout the winter. This strategy requires maximum light exposure, ideally a south-facing window or supplemental full-spectrum grow lights for a minimum of six hours daily. Maintaining warmth is also a factor, with temperatures suited to a normal living space, between 60°F and 70°F (15°C to 21°C).
Care requirements shift for an actively growing plant, but watering must still be reduced compared to summer months. The soil should dry slightly between waterings to prevent fungal issues. Pest vigilance is important in the dry indoor air, which favors spider mites and whiteflies, so regular inspection of the leaf undersides is advised. Fertilizing should be stopped or severely limited until new growth begins in early spring.
Spring Reintroduction
The transition back outdoors in spring is a gradual process that must wait until all danger of frost is past and nighttime temperatures consistently remain above 50°F (10°C). Moving the plant directly from an indoor setting to full, harsh outdoor sun and wind will cause severe leaf burn and shock. To prevent this, the lantana must be “hardened off,” a process that reintroduces it to outdoor conditions slowly over seven to fourteen days.
Begin by placing the plant in a sheltered, shady location for a few hours each day, gradually increasing the duration of its outdoor stay. Over the hardening period, move the plant incrementally into brighter light and more exposed areas. Once the lantana is permanently outside, any dead or damaged growth should be pruned away to encourage fresh, vigorous new shoots. Begin a regular watering and fertilization schedule only after established new growth becomes apparent.