Certain words are going to strike fear into the minds of any serious gardener, and convolvulus and oxalis are near the top of the list. Justifiably so, as members of these genera can certainly cause any amount of grief to the gardener with their expansionary territorial ambitions.
But the picture is not quite so straightforward as that, as both also have many species that are very attractive.
At our current garden, we are spared the tribulations of convolvulus [if you suffer from it, my recommendation is to move] but we have several unwelcome oxalis species that ply their trade in our garden beds and lawns. Among those is the native creeping oxalis, O. exilis, which creeps its way through lawns and can infest pots. It is very hard to kill, as it can withstand most common lawn weedkiller. The best results are probably obtained from Hydrocotyle Killer.
Other pest species grow from little brown bulbs which had an enormous number of bulblets attached to them – you pull up the bulb and think all is well, but discover they sprout again the following year. It is simply an ongoing battle that you must plug away at. Dig up and burn any bulbs you find, try to make sure the plants do not flower and thus seed, and never get so disheartened that you give all altogether. It is a battle of attrition you cannot win, but one you must partake in anyway.
With that long preamble, it is not time to talk about some of the prettiest small flowering bulbs you will ever find – the delightful Oxalis species.
Some of these are a bit fussy and need a bit of delicate care, but they are certainly well worth the effort. To start with there is the magical O. massoniana. This is one of a multitude of bulbs that hail from South Africa, a very low-growing plant that is best grown in a large container, preferably terracotta. That preference has nothing to do with cultural needs, but because the colour of terracotta sets off the wonderful orange flowers to perfection.
Only growing a centimetre or so high, this lovely autumn/winter flowering plant has subdued orange flowers, each with a golden centre, carried over bright green foliage. We have a lovely bowl of these in a collection of pots on a north-facing wall. I think they are among the prettiest of all bulbs. I have heard of others who have tried it in the garden, but most agree that it is easier in pots.
We also grow a number of forms of the species O. purpurea, a quite variable species. I think the type is a green foliaged plant with shiny pink flowers. This is quite hardy but not too expansionary, although I think I would be a little chary about planting it in a warm sandy site, as I discovered a patch of it growing in a lawn at Cook’s Gardens in Wanganui.
There is a purple foliaged version of this plant, which looks fabulous even when it is not in flower, but even better when it is. Again, we have this growing in a large container but it has not increased wildly. Perhaps the best of these variations is a pure white flowered variety, with a golden centre. Again, pots are probably best for this variety.
Another South African species with a variety of forms is the taller growing O. hirta. This has grown up to 25cm high, the usual green trifoliate leaves, and masses of flowers. The usual form has magenta blooms, but there are pink, salmon and cherry-coloured cultivars, all of which are easy to grow.
If you are looking for a different white flowered bulb you could do worse that the barbers’ pole oxalis, O. versicolor. As the common name suggests, the beauty has very attractive buds, pure white but each petal edges with red, so the effect is that of an old-fashioned barber’s pole. The white flowers are somewhat plain, but the buds are well worth growing on their own.
The first oxalis I ever internationally grew with the bright yellow species O. lobata. This has sunshine-bright flowers twice a year if the conditions are right, one of which will be in m id-winter. The repeat flowering is dependent on the plant receiving enough extra water.
There is a double flowering form of a similar species – O. compressa ’Flore Pleno’. This sends up clusters of very double flowers from tiny bulbs, each spike reaching about 10cm. again, this is great for growing in a container.
For something completely different, you should try O. palmifrons, which has succulent leaves, each dissected into upwards of twenty pieces, giving the effect of a dwarf-growing, ground-hugging palm tree. This is definitely one for container growning in a warm spot.
