Cultivation of Rhodohypoxis and x Rhodoxis
On seeing pots of Rhodohypoxis in full flower one of the first questions people ask us, is "Are they hardy?".
As these plants grow mainly in the Drakensburg Mountains of South Africa at altitudes of 1000 - 3000 metres the obvious answer would appear to be 'yes'. However, as we hope to build up a reputation as a nursery which can be trusted, and wanting our customers to return to us in future years we have to add the proviso, 'so long as they do not get too wet in the winter months'. In their place of origin they can have very cold but dry winters where they are often covered in snow. The key word in the last sentence is DRY. They can take it dry and cold but not wet and cold. As well as having dry winters the areas where Rhodohypoxis grow in South Africa also have high summer rainfall, so plants also require plenty of moisture in the summer growing seasons.
Certainly in some parts of this country, in very well drained soils where temperatures do not plummet to well below freezing, then many Rhodohypoxis will quite happily over-winter outside. Their chances of survival can be enhanced by placing a pane of glass, or polythene sheeting over the top of them during their dormant period.
Alternatively, if you have a heavy or poorly drained soil which stays sodden over winter we hope the following container cultivation notes will be of use to you.
Rhodohypoxis can be easily grown in containers where their growing conditions can be more easily controlled. Once again, containerised plants require plenty of moisture in the summer which is reduced as the leaves start to die down in August to October depending on the variety. Plants can then be stored dry, with no heating, under the bench of a glasshouse, in a shed or as we do, in the garage. Remove the dried leaves as they die down. If kept dry, we have found they can withstand temperatures of -12 C, if not more.
Please note: Do NOT leave Rhodohypoxis on top of the bench in a glasshouse during their dormant period as even in winter the sun can raise temperature under glass to a degree where the corms may desiccate.
Repotting is generally carried out in January or February with the first watering given in February, or more usually March, providing temperatures are not too low. Although much of the literature on Rhodohypoxis recommends acidic composts we have not found this to be absolutely essential, although pH of 6 to 6.5 is ideal. The compost should be relatively free draining which we achieve by adding from 25 - 40% coarse grit to the growing media.
It is important that plants are not allowed to dry out once they come into growth. Once the risk of a severe frost is over, plants can be placed outside in an open sunny site.
Regular dead-heading of the spent flowers helps to improve flowering performance.
We find that the plants have quite a hungry root system and for this reason are better if given the occasional supplementary potash-based liquid feed (tomato feed) throughout the growing season, or alternatively add a high potash slow release fertilizer into the compost at potting time. 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 do not dry out as quickly.
Rhodohypoxis are generally trouble free in respect of attack from pests and diseases. We have however heard of several cases where dry corms have been eaten by mice especially in colder weather although we have not (to date) experienced this problem ourselves, possibly this is aided by 'Little Bridgette', a very efficient 'Rodent Control Officer' - the cat! Squirrels have also been reported as being a pest of growing plants. Apparently, Western Flower Thrip can also cause problems in dry summers.
The most common method of propagation is to divide the corm-like roots during their resting period, usually just before re-potting. Alternatively, they can be divided whilst in active growth providing they are kept well watered.
The cultivation methods for x Rhodoxis are exactly the same as for Rhodohypoxis.
We are frequently asked how Rhodohypoxis multiply.
The answer to this is - by sexual means, seed and vegetatively - producing 'off-sets' / 'stolons'.
According to O.M. Hilliard and B.L. Burtt, two botanists that did a lot of field research into south African plants and have written papers on Rhodohypoxis (1975 and 1978) they describe them as not true bulbs (which are modified leaves or thickened leaf bases) nor true corms (condensed, vertical stem). In fact they described them as such -'
Rhodohypoxis are herbs with short swollen, vertical subterranean mucilaginous axis, with fleshy contractile roots as well as other thin ones; subterranean pseudostems up to 5cm long (according to depth of soil) composed of colourless, membranous, tubular, sheathing leaf-bases. A few species of Hypoxis have true corms.
Vegetative propagation is affected by underground stolons, which bear reduced colourless leaves. It seems that the axis of the stolons is relatively short-lived and decays soon after the apical parts send up arial leaves and becomes established as a separate plant.'
Below are photographs of a selection of different root systems found in various types of Rhodohypoxis.
................................................................Young plants just breaking into growth................................'Offsets' beginning to be produced.
The photograph on the left shows two 'offsets' produced from the parent plant. The one on the right shows two young plants entwined with the darker roots being contractile roots.
......................Collection of 'offsets' .....................................................with underground stolons appearing.
The two photographs above show a collection of plants with stolons still attached. The darker 'wrinkled / lined' roots in the left-hand photograph are contractile roots.