Ceanothus 'Trewithen Blue' Tree

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. Ceanothus require a well drained soil and sunny situation that is not exposed to drying winds.

AKA Californian lilac, Ceanothus arboreus 'Trewithen Blue'

• Common name: Californian Lilac tree
• Latin name: Ceanothus 'Trewithen Blue'
• Awards: RHS Award of Garden Merit
• Height and spread in 20 years: 3 x 3 metres
• Seasons of interest: Spring, Summer, Autumn, Winter
• Foliage: Dark green, evergreen leaves
• Flowers: Blue flowers in spring and summer
• Soil: Prefers moist, well-drained sites and all soil types except clay

Planting Advice for Ceanothus Trewithen Blue Trees

Our pot grown Californian Lilac trees can be planted at any time of the year. Choose a sunny position for this species and dig a square hole as deep as the root mass and approximately twice as wide. To help it establish, remove weeds and grass within a metre of the planting hole and sprinkle root grow inside the hole.

Remove the pot, gently loosen the roots and place into the planting hole. Mix 50% of the original soil with 50% compost, fill in the hole and firm around gently. Avoid banking the soil up around the collar of the tree.

We recommend planting single stem Ceanothus trees with a stake and tie. Place the stake at an angle to the tree to avoid penetrating the rootmass and knock in until it is firm. Tie the tree firmly to the stake using a tree tie.

Aftercare of Ceanothus Trewithen Blue Trees

If you’re planting Ceanothus in spring or summer, water well for the first few months. Increase watering if there are extended periods of hot or dry weather. If planting in autumn, you may only need to water a little. Irrigation kits make watering easier.

Once planted, keep the area free of competing weeds and grass for the first couple of growing seasons. If your area is prone to rabbits, use a rabbit guard.

Pruning Advice for Ceanothus Trewithen Blue Trees

Ceanothus trees 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.

Covid-19: We're pleased to announce that we are back up and running in line with government advice. We have a bit of a backlog of orders and are catching up as we write. Please expect a slightly longer lead time of around 2 – 3 weeks (excludes pre-order and mature trees). Thank you for your patience and understanding.

Delivery Costs

1 small tree (most trees under 1.5 metres in height) : £7.95 + vat

1 medium tree (most trees 1.5-2 metres in height) or 2-4 small trees: £9.95 + vat

2+ medium trees or 5+ small trees: £12.95 + vat

1-4 trees delivered by pallet (inc. mature Japanese Maples): £19.95 + vat

The above prices exclude the Scottish Highlands, where delivery starts from £24.95 + vat and is calculated in the checkout process.

Mature and pleached trees or orders too large for pallet: Cost is calculated in the checkout process and varies by postcode rather than quantity (starts from £48 + vat).

Northern Ireland and Non Mainland UK

Our courier charges are not viable for just one or two trees, but if you have a larger requirement then please do speak to us to see if we can find a solution.

Delivery Timescales

All trees are carefully packed by our experienced team and most are delivered within 10 days of placing the order. There's no need to be in to receive your order and you can request where it is left via the checkout.

There is a slightly longer timescale on pleached and mature trees (trees over 2.5m in height) because we group orders together for specialist delivery - we will contact these customers to notify them of the delivery date.

Trees on pre-order are still growing and an estimate of when they will be ready is given on the basket page. Orders will be despatched when all trees are ready.

Gift trees and those required by a specific date can be accommodated with pleasure, although we accept no legal responsibility for late deliveries.

Our nursery is a busy despatch centre, so please make an appointment to collect or view trees.  For collections, despatch charges will be refunded.

The product table at the bottom of the page gives the forms and sizes available for this variety. Please note, photos are a guideline as all plants are unique. Below are definitions of terms:

Supplied Size: Height measured from the top of the pot.

Single Stem / Pruned and shaped: Classic shaped tree with a single stem that has had pruning to help create a beautiful, natural shape.

Top grafted: A height noted next to this form refers to the length of clear stem, which will not grow taller. Only the head of branches will develop. Top grafted trees do not require complicated pruning and are ideal for small spaces.

Feathered: A feathered tree has branches from the bottom of the trunk all the way up. These branches can be removed if a clear stem is required.

Multi Stem: A multi stem tree has two or more stems arising from or near ground level, growing from one root system.

Bush: A plant with many stems low down, rather than one clear stem.

Clump: Several plants in one pot that can give the appearance of a multi stemmed and very bushy tree.

Climber: A plant that is a natural climber and will be delivered usually running up a bamboo cane, ready to position in the garden.

Standard Tree: A more mature tree with an upright clear stem of approximately 1.8m-2.0m (measured from the soil to the lowest branches of the crown). Standards are available in different forms relating to their girth size (circumference of the stem measured 1m above soil level), not height:

Standard  either 6-10cm or 8-10cm girth, approximately 2.5-3.0m in height
Premium Standard  10-12cm girth, approximately 3.0-3.5m in height
Heavy Standard  12-14cm girth, approximately 3.5-4.5m in height
Extra Heavy Standard 14-16cm girth approximately 4.0-6m in height