Grown for its intensely dark blue flowers caryopteris x clandonensis 39heavenly blue39 adds colour to fading borders in late summer and autumn this well45known and popular cultivar attracts pollinating insects and is a useful choice for providing late45season nectar in mixed borders cottage gardens and wildlife areas a superb deciduous shrub caryopteris x clandonensis is compact with an appealing rounded habit that remains manageable and neat even in smaller gardens height