TIPS ON HOW TO CULTIVATE WINTER GROWING SOUTH AFRICAN BULBS.
The two main requirements for successfully growing these bulbs or corms are -
1. Excellent drainage and
2. A dry rest period during summer dormancy.
If you have not grown Winter Growing South African bulbs before we have made a few suggestions below on how to do so based on our own experiences. No doubt other people have different methods but the way we describe is successful for us in the South of England and other people we have spoken to living in other parts of the country use similar methods. The best thing to do, is have a go and find out what is best for you but here are a few tips to start you on your way. However, be warned. .... it's addictive !
Potting can begin in August. However, do not start watering until the weather cools down; usually in September or October. Pot all bulbs by the end of October.
Watering - Winter growing South African bulbs require a dry summer rest; if they do not get this they will sometimes fail to produce growth in the autumn. Watering may be started in September and continues through the winter until the foliage starts to go yellow and die, usually in April / May. Watering in mid winter should be done with caution and it is advisable to wait until the pot is light in weight when lifted, or there is a slight limpness in the leaves indicating that water is required. During the main spring flowering season, watering needs to be more copious. Once the bulbs are in active growth they can be given a weak liquid feed, high in potash, such as a tomato feed, once a fortnight. Feeding will help to produce strong growth of the bulbs and induce flowering.
Discontinue feeding after flowering. The leaves of plants will soon begin to yellow. This signals the on-set of dormancy. Reduce watering and let foliage die back. Discontinue watering when leaves have withered. Do NOT water during summer dormancy. Once the compost has dried completely store in a dry location. However, there is always an exception (or two !) to the rule and a few will tolerate some summer water; e.g.Chasmanthe species, some Freesias, Gladiolus tristis and most Watsonias to name just a few.
Light - During the winter they will need as much light as possible but it may be necessary to apply some shading towards the end of March to prevent scorching of the leaves and to keep them in growth for as long as possible to produce larger bulbs for the following season.
Protection / Temperature - In the main, the hardiness of winter growing South African bulbs in Britain has not been tested, therefore it is advisable to grow your bulbs in a frost-free greenhouse, ideally with a minimum temperature for some subjects of 3C. Greenhouses should be ventilated whenever the outside temperatures allow.
Composts - Generally the compost should be neutral to slightly acid and free-draining. An example is 1 part John Innes No.2 compost, 1 part ericaceous compost and 2 parts coarse grit or Perlite. Re-potting annually is recommended as after 12 months the compost will begin to lose its structure and consequently its drainage capacity, plus food reserves
Pest and Diseases - Keep an eye out for aphids and squash between fingers, treat with soft-soap, chemical or biological control as soon as identified as they can transfer viral infections. Fungal and bacterial rots may occur to the bulb / roots and are commonly a result of incorrect watering, perhaps in combination with unsuitable composts.
Most importantly .......... ENJOY !