These evergreen or deciduous shrubs or 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.
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.
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Some low growing varieties make useful ground cover plants.and others are suited to container culture.
Pests & Diseases;
They can be susceptible to honey fungus and scale insect attacks.
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.
Note; Do not cut into older wood as the stumps may not regrow.
Pruning;
If found necessary; the flowering period will determine the best time to do it.
Similarly; Desired plant shape can affect the method of pruning.
Timing;
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)
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.
Training;
The aim in the first couple of years is to develop the general shape and size of each shrub.
Do this by shortening all stems by up to 60% or 70% in successive years until the desired shape is achieved then follow the general pruning advice above.
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.
Established plants;
After flowering; Prune out flowered stems by about 50%.
Weaker sideshoots can be pruned a little bit harder; cut 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.
Note; Overgrown evergreen shrubs do not respond well to heavy renovation, so it might be better to consider replacing them!.
Cultivation;
Week 9; 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.
Week 13; 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; for Deciduous varieties;and Week 28; for evergreen varieties;
Take 75mm (3") heel cuttings using firm lateral shoots, inserting them into a compost of equal parts( by volume) peat & river sand, and root at 16°C (60°F).
Note;Some success can be had from taking semi-ripe cuttings from evergreens and softwood or tip cuttings from deciduous plants.
Pot on rooted cuttings into 75mm (3") pots of potting compost and over-winter in a cold frame or cool greenhouse.
Week 18; They require no regular pruning other that required to keep them tidy and within limits.
This is particularly so with deciduous varieties.
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
Week 20; Pot up cuttings (taken the previous season) into 125-150mm (5"-6") and grow on until planting out time in September (Week 35)
Week 35; Plant out in good, fertile well drained garden soil in an open sunny position, or against a south or west facing wall.(avoid frost pockets)
Note;Deciduous varieties can stand more exposure to the elements as 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.
Note;If unable to plant out purchased plants at this time, then plant out any time between now and March if weather & 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
