What to do
* Cut back broom when it has finished flowering, shortening flowered shoots to within a couple of inches of the old wood.
* Dead head lilac and cut back Clematis montana if it is threatening to engulf other shrubs.
* Take out some of the old wands of growth on Rubus tridel to encourage fresh growth from the base of the shrub.
* Shear over clumps of aubrieta and arabis to remove dead flower heads. Work over alyssum bushes, cutting out old flower stems.
* Watch out for suckers on roses. They always spring from the base of the shrub and the foliage often looks different from that of the parent plant. Pull them off before they get too dominant. Loosely tie in sappy new growths of climbing roses so they do not get beaten about or snapped by wind. Old stockings or tights are ideal for this kind of job.
* Cut back the foliage of early flowering Iris unguicularis so that sun can warm the rhizomes.
* Sycamore seedlings are springing up faster than dragons' teeth. Remove them before they get too firm a hold.
* Prune out all green shoots on variegated shrubs such as ivies and trees such as the variegated sycamore. Green shoots have more vigour than the variegated ones and can quickly take over the entire plant.
* Pinch out flower buds from shrubs that you grow mainly for their foliage, such as senecio (now brachyglottis) and coleus. Herbs such as chives also benefit from this sort of treatment. Cut back the fading flower heads of spurges such as Euphorbia polychroma.
What to see
Open Gardens this summer celebrates the 30th anniversary of the Society of Garden Designers by providing access to 30 private gardens designed by members of the SDA. 11 of them will be open (2-6) on 26 June, including Mathew Bell's roof garden on the Blue Fin Building, 110 Southwark St, London SE1 0SU. For more information go to www.sgd.org.uk NDSReuse content