Having blue flowers in the garden is rather uncommon. One of the advantages of the Ceanothus soap bush is that it comes in a range of blue hues from pastel blue to deep indigo.
Depending on the variety, soap bushes spread their blooming in an infinity of hues.
The often intense blue soap bushes revel in the spring sun, and hold on to their leaves for us over the winter, too.
Since they grow very fast, soap bushes tend to have lush, dense stems. They are very easy to grow in temperate climates and show an excellent resistance to air pollution. Once they’ve set their root system up, drought is tolerated quite well, too, although having some moisture in the air helps.
Soap bushes come in a variety of shapes: some sprawl along the ground, others sit quite upright and even form tree-like silhouettes. This wide range makes the plant very appealing to creative gardeners who can let their imagination run wild.
Dressing up a pergola, fence or wall produces best results with taller varieties that you’ll tether to a lattice in a very sunny spot. When attached to a support structure, soap bushes can grow up to twice the height of normal bushes. Spreading, sprawling soap bushes are often used as ground cover on mounds of dirt and on rocky ground.
Soap bushes come in very different shapes, and the shape decides the job the plant can do. Here is how each habit described above is best put to use.
| Habit | Best use | Where it works |
|---|---|---|
| Compact, tight-growing | Pot and container growing | Balcony, in a box at least 16 inches (40 cm) deep |
| Spreading, sprawling | Ground cover | Mounds of dirt, rocky ground, staircase and balcony edges |
| Tall varieties | Dressing a vertical surface | Pergola, fence or wall, tethered to a lattice in full sun |
| Upright to tree-like | Free-standing specimen in a shrub bed | Open ground, with room left around it to spread |
Whichever shape you pick, letting the shrub grow its own way is what preserves its natural elegance.
Each soap bush carries its own shade of blue on its own frame, so the shape of the shrub matters as much as the colour. The table below sets the most widely sold varieties side by side.
| Variety | Shade of blue | Flowering period | Best use |
|---|---|---|---|
| ‘Trewithen Blue’ | Mid blue, scented | Spring | Tall screen, mild gardens |
| ‘Autumnal Blue’ | Sky blue | Summer into autumn | Late colour, wall training |
| ‘Concha’ | Deep indigo, red buds | Late spring | Free-standing specimen |
| ‘Gloire de Versailles’ | Powder blue | Summer into autumn | Mixed border, colder gardens |
| ‘Skylark’ | Deep blue | Late spring to early summer | Small garden, container |
For a balcony, select a variety known to be suited to growing in pots. Your soap bush will amaze you and if you pair it with other easy shrubs like Russian sage, althea, Mexican orange tree, rosemary, Portugal laurel, lavender and bulbs and perennials.
As much as possible, let the soap bush run its course as it grows to preserve its natural elegance: crawling types can dress a staircase or balcony edge quite well, and will dribble down tall earth mounds with ease. Match your soap bushes with shrubs that bear light-colored leaves, such as the katsura tree. Finish the arrangement off with a few bulbs or yellow-blooming perennials.
