Key features
AwardsRHS Award of Garden Merit
Final size3 x 3 metres in 20 years
FoliageGreen leaves year-round (evergreen)
FlowersBlue flowers in summer
PositionFull sun
SoilRequires well-draining soil
Description
Ceanothus ‘Trewithen Blue’ is a fantastic evergreen tree with profuse, rich blue summer flowers emerging in clusters from April through to June. Ceanothus, also known as Californian Lilac, are very popular with bees and butterflies due to the mass of flowers that cover them. The evergreen oval foliage provides a dark-green foil for neighbouring plants in summer and substance to the garden in winter.
It can be grown as a a small tree reaching up to 3 metres in height or as a climbing shrub. We offer both single stem and multi stem Ceanothus trees, but they can also be grown as a climbing shrub by training them against a wall if you wish. If you’re looking for a patio version, see Ceanothus thyrsiflorus repens.
Ceanothus ‘Trewithen Blue’ is great for year round interest, with its profuse blue flowers and evergreen foliage. Originating from California, Ceanothus require a well drained soil and sunny situation that is not exposed to drying winds.
AKA Californian Lilac, Ceanothus arboreus ‘Trewithen Blue’
Planting Steps
1Preparation
- Pot-grown plants can be planted at any time of year, whereas bare roots need to be planted between November and March.
- Clear weeds and grass within a metre of the planting hole.
- Dig a hole as deep as the root mass and twice as wide.
- To help your plant establish more effectively, sprinkle Rootgrow in the hole.
2Planting
- Gently loosen the roots and place into the planting hole.
- Ensure the top of the plant’s compost is flush with the level of the surrounding soil and the graft union or collar of the tree is above ground level.
- Mix 50% of the original soil with 50% compost.
- Fill in the hole, firming the soil gently.
3Last Steps
- Water generously around the base of the plant.
- If you are planting either a single stem tree or mature standard tree, we recommend adding a staking kit and rabbit guard.
Aftercare Advice
Ceanothus require a good watering regime for a couple of years whilst they establish. Water well and regularly through spring and summer, increasing in hot or dry weather. If planting in autumn, you may only need to water a little. It is advisable to keep the area free of competing weeds and grass during this period.
Ceanothus do not require a lot of pruning. Simply remove any dead, diseased or awkwardly placed branches from the tree as and when you see them.
For more detailed advice and video guides, please visit our Help & Advice section.
