This genus includes 45-50 species of deciduous or evergreen shrubs originating in North America, especially California.
The most cultivated species in the gardens is evergreen, slow growing, with small dark green leaves on the upper side, greyish-green on the lower side and slightly pubescent.
The bark of California lilacs is green in young specimens, with time it turns brown; from spring to early summer it produces small white or blue flowers, gathered in showy panicles.
The California lilac plants are a variety of easy cultivation, both in pots and in the open ground.
These rustic-looking shrubs, which reach about 2 meters in height, prefer bright locations, even exposed to direct sunlight for a few hours; they do not fear the winter cold, but it is advisable to put them at home i ceanothus in a place protected from cold winds also because their root system is rather small and could be ruined by the wind.
They are hardy and resistant plants that manage to withstand well even the changes in temperature, but in case of very harsh climate it is good to place them in a more sheltered corner.
The California lilac has a rustic structure that makes it rather resistant.
From March to October, during the vegetative and flowering period, it is advisable to water abundantly, almost always maintaining the moist soil, checking however that water does not form, harmful to the plant.
In winter, reduce watering without suspending it completely, always checking that there is not an excessive presence of water that could lead to the onset of dangerous and harmful root rot.
At the end of winter it would be advisable to supply the soil where the mature manure is found.
Every 15-20 days, provide fertilizer for flowering plants in the growing season.
California lilac plants prefer loose, well-drained soils rich in organic matter.
It is advisable to prepare an ideal compote by mixing balanced soil with a small amount of sand and perlite, to increase drainage.
They grow more difficult in limestone-rich soils, but they manage to have a good adaptation. When the type of soil is not the right one, they can present iron chlorosis problems, which leads to the yellowing of the leaves. In this case it is possible to intervene by supplying iron supplements.
The multiplication of these plants occurs by semi-woody cutting and is practiced in summer; practice numerous cuttings, since rooting is not always easy.
The new plants should be grown for a couple of years in pot before they can be planted.
The ceanothus can also be sown, but the daughter plants do not always have flowers equal to those of the mother plants, moreover the germination is not easy; in nature, ceanothus seeds germinate more easily after a fire.
California lilac - Ceanothus: Pests and diseases
Being a type of rustic plant, the California lilac is hardly affected by pests and diseases, but, especially if cultivated in calcareous soils, it particularly fears ferric chlorosis, which can be easily avoided by occasionally supplying iron-based fertilizers.