Winter-growers are plants which grow and flower, both in their habitat and in our climate, in the period from autumn till the beginning of spring. In general, winter-growers are more difficult to keep in cultivation than summer-growers. Almost all known winter-growers are native to South Africa and Namibia. Genera with only winter-growing species are Lachenalia, Gethyllis, Haemanthus, Massonia and Veltheimia. Genera with winter-growing species as well as summer-growing species are, e.g., Albuca, Gladiolus, Cyrtanthus and Ornithogalum.
Storage
In general, the temperature during the dormant period for winter-growers is 18-22 ºC, which can be realized in our summers. The plants need protection against direct sunlight and high temperatures(>25 ºC). Direct sunlight and temperatures which are too high can lead to the drying out of the plants and deformation of the main bud, and secondly to the abortion of the main bud.
Growing temperatures
Winter-growers desire a growing temperature of 12-17 ºC and are suited for a cool, unheated, room or slightly heated glass-house.
A special point of attention during the growing and flowering period is the relative humidity in autumn and early winter. Because of the drop in outside temperatures, the relative humidity rises and the air can become saturated with water vapour. When the humidity reaches a 100%, condensation will form. The water drops can fall on the plants and on the soil surface. These water drops encourage the growth of fungi.
When a plant is affected by a fungal disease, it is very difficult to get rid of it completely. It is often advisable to keep the infected plant separate from the other, healthy, plants and to keep it on the dry side for some time. The plant can also be treated with one of the available chemicals. One way of lowering the humidity is by increasing the heating, while simultaneously opening the windows. The duration of this process depends on the size of the room or greenhouse and the extent of the humidity problem. The method is effective, but expensive.
Watering
The plants grow in a period of short days and of a low light intensity. This means in general that plants doesn't need and use a lot of water. Keep this in mind when you water your winter growing bulbs. It is better to grow them 'to dry' than 'to wet'. Futhermore it is better to grow them in a small pot.