Weekend Work: Time to clip the berberis hedge

What to do

Where berberis is grown freely as a shrub, it does not need regular pruning, though old evergreen specimens can be rejuvenated by cutting out some of the old stems at ground level. This will persuade the thing to throw some vigorous new shoots. Berberis hedges need clipping to shape at least once a year and now is the right time to be doing the job.

Box hedges and topiary need trimming only once a year. This month or the next is the best time. Topiary needs a careful eye. Most of the best topiary artists use hand shears rather than mechanical trimmers. Holly makes more uncomfortable topiary, but as with box, it should be clipped to shape this month.

Established hedges of beech should be trimmed now. If you do not have a good eye for a straight line, stretch a string along the hedge to give you a guide.

If you have not already done so, thin out the old wood of philadelphus. Do not prune by shearing over the whole shrub. If you do this, you will remove the new wood which will bear next year's flowers. On the other hand, if you do nothing, the shrub will grow unreasonably large.

Bushes of santolina (cotton lavender) get open and leggy with age. As soon as it has finished flowering, cut hard back to encourage new growth from the base. Lavender is loath to sprout from old wood, but santolina does and will look much better next year if you give it harsh treatment now.

What to see

The Chelsea Physic Garden still gives visitors a delicious sense of being in a secret place. You slip in through the door in the high wall that surrounds it and find yourself in an unexpectedly serene (and beautifully tended) space. Every Wednesday through August, the garden is staying open from midday until 10pm. Admission £8. Wine available from the café. For more information call 020 7352 5646 or visit www.chelseaphysicgarden.co.uk