Common name: Californian Lilac
These evergreen or deciduous shrubs /small trees grow to around 3metres (10ft) in height with a similar spread.
Panicles of small pale blue flowers appear in late May early June on evergreens varieties and August to September on deciduous varieties.
Shrub in Flower
Close up of Flower
Both types are drought and lime tolerant but plants can suffer from chlorosis (yellowing of the leaves)on shallow, chalky soils due to nutrient deficiency, and or if the soil is too wet.
Some low growing varieties make useful ground cover plants.and others are suited to container culture
Pests and Diseases:
They can be susceptible to honey fungus and scale insect attacks.
If found necessary the flowering period will in most cases, determine the best time to prune.
Spring / Early summer flowering shrubs:
Cut back any long spindly shoots that have finshed flowering by 30%-50% of their length.
Later in the summer some shrubs may need a little light trimming to enhance the shape.
Late summer-flowering shrubs:
These can be a bit more tricky to prune due to spring flowers appearing on shoots that grew the previous summer, and summer flowers that grew on the current year's growth.
Trim the previous season’s growth by one-third to a half in spring.(circa week 18)
Pruning Evergreen varieties:
Routine pruning is not essential, in fact it is often considered best not to prune at all.
Pinching our / pruning the soft tips on young plants with secateurs is generally all that is required.
Do not cut into older wood as the stumps may not regrow.
Pruning Deciduous shrubs:
These bear flowers on new shoots during the summer months .
Any routine pruning is usually carried out annually in early spring (circa week 18)
This encourages the shrubs to generate many new shoots,resulting in potentially more flowers.
The aim in the first couple of years is to develop the general shape and size of each shrub.
Do this by shortening all the stems by up to 60% or 70%.
Close up of panicle
In the second year secondary shoots of previous season’s growth should be cut back to 100-200mm from the main branch/s
All cuts should be made at an outward facing bud.
In successive years until the desired shape is achieved, follow the general pruning advice above.in successive years until the desired shape is achieved then follow the general pruning advice above.
Pruning Established plants:
After flowering, prune out flowered stems by about 50%.
Weaker sideshoots can be pruned a little bit harder by cutting back to about 2-3 buds from the main stem.
Thin out congested or unproductive growth from the centre of the shrub as deemed necessary.
Overgrown evergreen shrubs do not respond well to heavy renovation, so it might be better to consider replacing them.
Sow seed in trays of seed compost and germinate at a temperature of 16°-18°C (60°-64°F).
Dousing the seeds in boiling water for a few seconds can aid the germination process.
Germination should take three to four weeks.
When seedlings are large enough to handle prick them out into 70mm(3") pots of potting compost and grow on in a coldframe until planting out time.
Circa Week 13:
Take 75mm (3") heel cuttings of deciduous varieties using firm lateral shoots, inserting them into a compost of equal parts( by volume) peat and river sand, and root at 16°C (60°F).
Wait until Week 28 to take heel cuttings from evergreen varieties.
Note: Some success can sometmes be had by taking semi-hardwood cuttings from evergreens and softwood or tip cuttings from deciduous plants.
When rooted pot on cuttings into 75mm (3") pots of potting compost and over-winter in a cold frame or cool greenhouse.
Evergreen varieties may require frost damaged stems cutting back to healthy wood.
Apply 60g per square metre (2oz per square yard) of balanced fertiliser after pruning to encourage new growth.
Pot up cuttings (taken the previous season) into 125-150mm (5"-6") and grow on until planting out time in September (Week 35)
Plant out seedlings/cuttings in good, fertile well drained garden soil in an open sunny position, or against a south or west facing wall.
If such an area is unavailable you can consider planting them out in containers.
This will allow you to place them in a more desired area in summer, then move them to a more protected area for the winter months.
Deciduous varieties can stand more exposure to the elements than their evergreen counterparts.
Do not plant in exposed situations and frost pockets as the plants can be affected by winds and frost, similarly, avoid planting in wet soils
The root system can be damaged by excess moisture levels, leading to poor growth and dieback.
If unable to plant out purchased plants at this time, then plant out any time between now and March if weather and ground conditions allow.
Circa week 40:
Offer the plants some winter protection by applying a 75mm (3") mulch of organic matter.
Ensure that the mulch does not come in contact with the stem of the plant/s.