Rhodohypoxis and x Rhodoxis
Mr & Mrs C Birchall, Tale Valley Nursery, Devon, share the secrets of their success with their National Collection
Rhodohypoxis come from South Africa and Lesotho with their main centre of distribution being the Drakensberg Mountains where they grow at altitudes from 1500 to 3400 meters. There are 6 species, one of which (R. baurii) has three varieties. Two of the species, R. rubella and R. incompta are not in cultivation. In addition to this athere are approximately 150 cultivars. x Rhodoxis is a naturally occurring hybrid between Rhodohypoxis and the white flowered Hypoxis parvula and has about 20 cultivars. Unfortunately many of the cultivars of the two genera seem to be indistinct, particularly those introduced in recent years with no cross reference being made with existing plants.
Care of the plants
Successful cultivation outside generally depends on the soil type and the rainfall in the area (very dry summers and wet winters can cause problems). Rhodohypoxis require reasonably dry conditions during the winter and plenty of water in the summer, and grown this way are choice plants for the raised alpine bed, rock garden or cold frame. These conditions are often best provided by protecting them with a pane of glass or polythene sheeting during the winter months and ensuring plenty of moisture during the summer.
Alternatively they can be grown very easily in pots. If kept dry they can withstand temperatures to about -15c. They require plenty of moisture in the spring and summer which is reduced as the leaves start to die down in August to October. Plants can then be stored in an area such as a cold frame with no heating or, as we do, in an unheated garage. the leaves are best remobved as they die down to prevent fungal diseases. Re-potting is generally carried out in January to February and the first water given in March providing temperatures are not too low. Watering should be gradually increased as the shoots begin to emerge. It is essential that plants are not allowed to dry out once they have come into growth.
Acidic composts are generally recommended although we have found these not to be essential. The compost should be free draining which we achieve by adding up to 50% grit as this is lighter in weight and therefore easier for transportation purposes. other sources suggest the addtion of well rotted leaf-mould, John Innes compost, silver sand, coarse sand or moist sphagnum moss.
The plants generally have quite a hungry root system and for this reason are better if given the occasional potash based fertiliser (such as a tomato feed), throughout the growing season. We also find that they are best re-potted every year.
We tend to grow our plants in terracotta pots mainly for display purposes around the garden; they also grow equally well in plastic pots which are easier to maintain in the summer as they do not dry out as quickly.
Their main flowering flush is from May to June but this can be prolonged by regular dead-heading which also improves the flowering performance. Flowering can be delayed by disbudding the plants.
The cultivation requirements of x Rhodoxis are identifal to that of Rhodohypoxis.
Propagation by seed
Sow in spring, barely covering the seeds. Give plenty of light. Germination occurs in approximately 8 weeks. This method will produce flowering plants in two years which may show considerable and interesting variation. Flowers are pollinated either naturally by small insects or artificially by using a small artist's paintbrush. unfortunately swelling of the capsule can occur even when there is no seed within.
Divide during the resting period. Alternatively separating the corm-lik roots or dividing established clumps whilst in active growth has been found to be successful with most speices and cultivars, providing they are kept well watered.
Pests and diseases
Rhodohypoxis are generally trouble free. Mice are particularly fond of the dormant corms especially in colder weather though we have not encountered this problem ourselves, possibly this is because we have a very efficient Rodent Control Officer - the cat! Western flower thrip can cause problems in dry summers.