Ceanothus: the hardiest varieties
Discover our hardiest varieties for cold resistance.
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The ceanothus is an attractive bush that we love to plant in our gardens. Many varieties are derived from species native to California or Mexico and have a hardiness limited to -7 °C or -10 °C. The species with evergreen foliage are the least hardy. In any case, the essential condition for your bush to withstand the cold is to provide it with the recommended growing conditions. For ceanothus, this means ensuring well-drained soil and planting them sheltered from cold winds in a sunny position. Deciduous species can tolerate brief frosts down to -15 °C on average. They prefer cool soil and can tolerate a bit of lime in the soil.
Discover our hardiest Ceanothus, suitable for planting in various regions of France, except in the Mediterranean zone, which is too dry, and in continental and mountainous climates, which are too cold. In such cases, you might consider pot planting, which you can winter to get through the cold season.
Ceanothus delilianus 'Gloire de Versailles'
The Ceanothus ‘Gloire de Versailles’ is among the most cold-resistant. With deciduous foliage, it tolerates short frosts down to -15 °C, classified in USDA zone 7b. It showcases large, airy panicles of celestial blue flowers in summer and early autumn on a bushy, vigorous shrub that reaches 1.5 m in all directions at maturity. This horticultural hybrid was developed in France in 1830, resulting from the cross-breeding of a very hardy American species, Ceanothus americanus, and a much more tender Mexican species, Ceanothus caeruleus. It requires well-drained soil, preferably non-calcareous, remaining cool in summer.
Plant it in a free-standing hedge or in a border, where its long, slightly fragrant flowering, with its charming blue hue, enhances that of roses, accompanied by Cotinus with purple foliage and Lilac, creating a gradient of soft colours.
Ceanothus delilianus ‘Gloire de Versailles’
Ceanothus pallidus 'Marie Blue'
If this Ceanothus pallidus ‘Marie Blue’ withstands occasional frosts of -15 °C, once mature, young plants should be protected in case of forecasted cold. Plant it in a sheltered, sunny location. Like the Ceanothus ‘Gloire de Versailles’, it is not suited to the Mediterranean climate, which is too dry. It thrives in well-drained, fertile soil, without excess moisture. It tolerates slightly calcareous soil. As for its ornamental qualities: it produces a very abundant sky-blue flowering from July to September, on a small bushy plant, 1.5 m high and 1 m wide. Its soft green, deciduous leaves may persist if the climate is mild. They are borne on purple-red branches. Developed in 2003 by Minier nurseries, it is a result of cross-breeding between Ceanothus delilianus (the species of our dear ‘Gloire de Versailles’) and Ceanothus ovatus.
Plant it alongside a pink-flowering ceanothus that enjoys the same growing conditions, together with a Viburnum and a Mock Orange, for example, within a shrub border.
Ceanothus pallidus ‘Marie Blue’
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Ceanothus pallidus 'Marie Simon'
Featuring a rarer soft pink flowering among Ceanothus, the Ceanothus pallidus ‘Marie Simon’ boasts a bushy, rounded habit on a small bush reaching 1.75 m in height and 1.50 m in width. It delivers a long flowering period from July to September, with fluffy pink panicles borne on fine, well-ramified purple stems. The flowers open in salmon pink and transition to flesh pink. More suited to cooler climates than its Californian relatives, it is from the same species as ‘Marie Blue’: it enjoys the same growing conditions and similarly withstands adverse weather. Protect young plants; an established adult in well-drained soil can tolerate temperatures down to -15 °C, classified in zone 7b.
Plant it in a romantic setting with Lilacs and Deutzias for a harmonious pink display.
Ceanothus pallidus ‘Marie Simon’
Ceanothus pallidus 'Marie Rose'
The Ceanothus pallidus ‘Marie Rose’ is another variety with pink flowers, more compact than ‘Marie Simon’. It is an improvement in terms of floribundity. It develops a bushy clump 1.5 m high and 1 m wide. It flowers for the first time in June and July, then again in September and October. Its upright, purple stems bear flowers like pale pink clouds, measuring 7 to 10 cm long. These are followed by dark red fruit. If you remove these fruits, the second flowering occurs. This hybrid, created by Minier nurseries in 2006, continues the search for plants that are less sensitive to cold. It offers the same cold resistance as the other two varieties in the ‘Marie’ series. If you cut back its clump in winter, you further improve its hardiness. In a not too harsh climate, it can retain its foliage in winter.
In a small bed, plant it with summer-flowering perennials such as achilleas or gauras. Its small size also allows you to enjoy a ceanothus in a pot on your terrace.
Ceanothus pallidus ‘Marie Rose’
Ceanothus impressus 'Cool Blue'
While evergreen ceanothus are more sensitive to cold, this Ceanothus impressus ‘Cool Blue’ is one of the few evergreen specimens that withstands cold quite well. It is a hybrid derived from Ceanothus impressus, a species native to California, hence the name California Lilac sometimes used to describe it. This beautiful variegated ceanothus tolerates frosts of around -12 °C to -15 °C once mature. Care should also be taken with young plants, providing this bush with its preferred growing conditions. It tolerates dry soils and, like others, requires well-draining soil and a sheltered position. It features elegant foliage well-variegated with cream white, with small leaves full of light. Its bright light blue flowers appear abundantly in spring, in April and May. It forms an upright bush 2 m tall and 1.5 m wide.
This blue ceanothus can be planted in a dry garden as well as in fresh, well-drained soil. It makes a lovely specimen when planted alone.
Ceanothus impressus ‘Cool Blue’
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