The use of a pre-emergent weed killer may be tempting, but in the small garden situation, an organic mulch is far safer and more beneficial to the garden as a whole.
As the winter in Mediterranean climates is also the rainy season, weeds can germinate and cover wider areas so rampantly, that the gardener is usually interested in preventing weeds or at least keeping them down before they spread, develop, and really start to cause problems.
While one should be reluctant to use herbicides at the best of times, there are two kinds that are especially worth avoiding altogether.
Chemical weed killers or herbicides should be used as sparingly as possible in gardens as a whole, but especially in private ones. Excessive use of them is bad for the ecological balance in the garden itself, as much wild life is deterred from establishing itself, and in the wider sense, is a serious form of pollution.
There are uglier weeds than Wood Sorrel, (Oxalis) but not many as difficult to treat. Within a bed of ground cover plants for example, it can be disastrous.
Oxalis, commonly known as Wood Sorrel, is hardly one of the ugliest of weeds. On the contrary, many species are favored perennials in garden beds, with their delicate, clover-like leaves, and attractive blooms. Yet one species of Wood Sorrel, Oxalis pes-caprae, can be in certain circumstances, one of the most annoying and difficult weeds to eradicate.