Carpenterias in full flower are stunning evergreen shrubs for growing up against a wall or freestanding in a sunny border. Nevertheless, because they are usually rare and scarce in cultivation, slightly difficult to propagate and generally not understood as plants there is something of a question mark about growing them in the UK.
Carpenteria are a genus of only ones species which grows in scrub and pine forest in California. They are related to philadelphus and, in reality, they are just as easy to grow in the UK as mock oranges despite where they originate from.
These plants have handsome leaves and pure white flowers which are 2-3in in diameter in terminal clusters of three or seven flowers together. The stamens at the centre of the flower are a conspicuous yellow and flowers appear in June and July. In Cornwall the first usually appear in May and we have sometimes had them on the stand at Chelsea.
Although you might perhaps doubt it to look at them as young plants carpenteria are frost hardy. They may defoliate slightly in severe cold but will survive.
They grow best in full sun in not too dry soil with adequate shelter from cold, dry and strong winds. At Burncoose our stock plant has thrived for years by the mist house.
No pruning is necessary although, if they are grown up a wall, some tying-in may be necessary to get the shrub established. The plants can grow 6-12ft high in such situations but rather less in borders. The largest plants we have seen are in Suffolk!
Carpenteria will readily grow from seed but these can be variable with some producing rather small leaves and flowers. Greenwood or semi-ripe cuttings in summer with bottom heat can be successful although they are often not that quick to root.
We have a detailed how to collect, store and plant seeds if you are interested in knowing more.
This is certainly a plant which is well worth including in your garden!