The successful overwintering of the African lily is a critical aspect of its cultivation, particularly in climates that experience freezing winter temperatures. As a native of Southern Africa, its tolerance to cold varies significantly between different types and cultivars. A proper overwintering strategy ensures the plant’s survival through the dormant period and is fundamental for its vigorous return and prolific flowering in the following season. The approach to winter care depends heavily on whether the variety is deciduous or evergreen, and whether it is grown in a container or directly in the garden.
The primary goal of overwintering is to protect the plant’s fleshy rhizomes from freezing, which can cause irreparable damage and lead to the death of the plant. For deciduous varieties, which are generally hardier, the focus is on insulating the root zone from the most severe cold. For the more tender evergreen varieties, which retain their foliage, protection from frost is essential not only for the roots but also for the leaves. This often necessitates moving the plants to a protected location, such as a greenhouse, conservatory, or unheated garage.
Preparation for overwintering begins in the late summer and autumn, long before the first frost is expected. This involves adjusting the plant’s care regimen to encourage it to enter a state of dormancy naturally. Ceasing all fertilization by the end of summer is the first crucial step, as this prevents the growth of new, tender foliage that would be highly susceptible to frost damage. Gradually reducing the frequency of watering as the weather cools also signals to the plant that it is time to slow down and prepare for its winter rest.
The specific actions taken for overwintering will be determined by the local climate. In very mild regions where frosts are rare and light, both deciduous and evergreen varieties may be able to survive outdoors with minimal protection. However, in most temperate climates, a more proactive approach is required. Understanding the hardiness of your specific cultivar and the typical severity of your local winters will allow you to formulate the most effective strategy to ensure your African lily survives and thrives year after year.
Deciduous versus evergreen varieties
Understanding the fundamental difference between deciduous and evergreen African lilies is the key to determining the correct overwintering strategy. Deciduous varieties are native to the winter rainfall regions of South Africa and are adapted to a cool, wet dormant period. They naturally die back completely in the autumn, losing all their foliage, and remain dormant as bare rhizomes underground until spring. This characteristic generally makes them hardier than their evergreen counterparts, with some cultivars able to withstand temperatures down to approximately -10°C (14°F) or even lower if planted in well-drained soil and given a protective mulch.
Evergreen varieties, on the other hand, originate from the summer rainfall regions of South Africa, where winters are typically mild and dry. As their name suggests, they retain their leaves throughout the year, although their growth slows dramatically during the winter. Because they maintain their foliage, they are much more susceptible to frost damage, which can harm the leaves and, in severe cases, the crown of the plant. Evergreen types are generally considered tender and will require frost protection in any climate where temperatures regularly drop below freezing. They are ideally suited to container cultivation, which allows them to be easily moved to a protected location for the winter.
The preparation for winter differs slightly for each type. For deciduous plants in the garden, it is important to allow the leaves to yellow and wither naturally. This process allows the plant to draw all the energy from the foliage back down into the rhizomes for storage. Once the leaves have completely died back, they can be cleared away to maintain a tidy appearance and reduce the risk of pests and diseases overwintering in the debris. This tidying up should be done just before applying a winter mulch.
For evergreen varieties, the goal is to keep the foliage as healthy as possible through the winter, as these leaves will form the basis of the next season’s growth. Before moving potted evergreen plants to their winter quarters, it is a good practice to inspect them for any pests, such as mealybugs, and treat them accordingly. Removing any yellowing or dead leaves will help to improve air circulation and reduce the risk of fungal diseases like botrytis developing in the cool, damp conditions of their winter storage area.
Overwintering in the garden
Overwintering African lilies directly in the garden is a viable option primarily for the hardier, deciduous varieties and is only recommended in regions where winter temperatures do not consistently drop to extreme lows. The single most important factor for successful in-ground overwintering is excellent soil drainage. Plants left in heavy, waterlogged soil are far more likely to succumb to root rot during the cold, wet winter months than they are to the cold itself. Therefore, ensure the planting site is well-drained or amend the soil thoroughly before planting.
Once the foliage of the deciduous plants has completely died back in late autumn, and after the first light frost, it is time to apply a protective winter mulch. The purpose of the mulch is to insulate the soil and the rhizomes beneath from the coldest temperatures and from the damaging effects of repeated freezing and thawing cycles. A thick layer, around 10-15 centimeters deep, of a dry, airy material should be applied over the crown of the plant. Suitable materials include straw, bracken fern, bark chips, or even a pile of dry leaves.
This protective mulch should be left in place throughout the coldest part of the winter. It acts like a blanket, keeping the ground temperature more stable and preventing the frost from penetrating deep into the root zone. It is important to use a material that does not become overly compacted and waterlogged, as this could trap too much moisture around the crown and lead to rot. The mulch helps to create a drier and more insulated microclimate for the dormant rhizomes.
In early spring, as the threat of severe frost recedes and the soil begins to warm, the winter mulch should be carefully removed. This allows the sunlight to reach and warm the soil, which will encourage the plant to break its dormancy and send up new shoots. Leaving the mulch in place for too long can delay the emergence of new growth and can provide a hiding place for slugs and snails, which will readily feast on the tender new shoots.
Overwintering in containers
Container cultivation is the recommended method for growing African lilies in climates with cold winters, and it is essential for the tender evergreen varieties. The portability of pots allows the plants to be moved to a protected, frost-free location for the duration of the winter. The preparation for this move begins in the autumn with the gradual reduction of watering to help initiate dormancy. Before bringing the plants indoors, it is a good time to tidy them up by removing any dead or yellowing leaves.
The ideal winter storage location for a potted African lily is a place that is cool, bright, and frost-free. An unheated greenhouse, a conservatory, a well-lit porch, or even a cool windowsill in a spare room can be suitable. For evergreen varieties, it is important that the location provides enough light for the leaves to survive, so a dark shed or garage is not ideal unless it has a window. The temperature should ideally remain above freezing but cool enough to keep the plant in a dormant or semi-dormant state, typically in the range of 5-10°C (41-50°F).
Watering during the winter storage period must be drastically reduced. The aim is simply to prevent the rhizomes from completely drying out. For evergreen varieties, a small amount of water every three to four weeks is usually sufficient to keep the leaves hydrated. For deciduous varieties that have been stored in their pots, the soil should be kept almost entirely dry, with only a splash of water given once every month or two. Overwatering is the greatest danger during this period, so always err on the a side of caution.
As spring approaches and the days begin to lengthen, the plants can be gradually reacclimatized to warmer conditions. Watering can be slowly increased to encourage the start of new growth. Once the risk of all frost has passed, the containers can be moved back outdoors. It is important to do this gradually, hardening the plants off over a week or two by placing them outside for a few hours each day, to prevent the shock of a sudden change in temperature and light intensity.
