Contrary to what their exotic appearance might lead one to believe, salvia is one of the easiest plants to grow. But in a genus with such a large number of species, it would be unrealistic to follow a general rule. Southern Mexican salvia is not a tropical plant, but a mountain plant. Few species can be found below 1500 m, except in coastal areas exposed to a strong humid influence.
At high altitudes, they never grow on the northern and eastern slopes, but can be found up to 3000 m on the southern and western slopes of all the volcanic formations surrounding the central plateau.
In our climate, sunny exposure is the rule for almost all species, with modulation according to origin: the optimum is to aim for 100% exposure for tropical, subtropical and desert species to 50% for certain Far Eastern species. It is also important to avoid, as far as possible, the places most exposed to the wind.
The attraction of salvia to humans is that we respond to the same stimuli as the rest of the animal kingdom, to which - whether we like it or not - we belong. However, it is not we who are the target of these generously provided trappings. In order to ensure their survival, the so-called higher living beings need to mix their genes regularly. This is why nature invented sexuality. While this is relatively easy for the animal kingdom, which is endowed with movement, it is much more complicated for plants, which are condemned to immobility. In most cases, this requires the help of a third party - water, wind, insect, bird. While for the first two the intervention of chance is generally sufficient, seduction is necessary for the last two, the most attractive being, as is only natural, served first. The instruments of this seduction are, in order of intervention :
Salvia: A colour that can be seen from afar. It is now generally agreed that the reds and some of the bright blues are aimed at birds (especially hummingbirds, in the case of New World sage) and the other colours at insects.
A salvia plant, which is intended to guide the pollinator efficiently: the lower lip forms an ideal landing strip, often marked with a pair of white lines. This characteristic is often less pronounced in the red species, which the hummingbirds collect in flight: the lower lip is generally less developed and the white line marking is, in this case, absent.
The food of the salvia drips in the form of sweet nectar from the bottom of the funnel-shaped corolla. However, in order to mix its genes effectively, seduction is a necessary, but not sufficient condition.
Among the seductive factors of the salvia flower, the reader will have noticed that we have not mentioned the smell. Unlike many plants that use the scent exhaled by their flowers to attract pollinating insects (often by plagiarising pheromones), sage flowers are odourless (which is only logical, as they are often pollinated by birds, which are generally devoid of a sense of smell).
On the contrary, the odoriferous glands that they share with many members of the Lamiaceae family and which dispense heady odours, are probably a means of cooling by evaporation of volatile essences, unless it is a means of defence against predators: their effectiveness is proven in most cases. Thanks to them, sage is less prone than others to aphid infestations and is spared by goats and other ruminants. However, this protection is not universal: some species of sage are subject to attack by various insects, mites and other pests, despite the powerful smell they give off. Almost all of them are a delight for gastropods, especially when the salvia shoots are young. Finally, instead of being repelled, humans find these scents an additional seductive factor. I confess that I am interested in sage as much to satisfy my sense of smell as my sight.
Some salvias, such as blackcurrant salvia or blackcurrant plant, also have an interesting taste for culinary use.