Weekend Work: Dig out the watering can

What to do

Watering is now a priority. Clay ground may already have cracked into craters, despite what seemed like plenty of rain in May. Hydrangeas flag badly when water is short; it has also been difficult to get young brassica plants established. Water them in their holes like leeks before stamping the ground round their stems.

The most efficient way to water single important plants is through a pot or length of drainpipe sunk into the ground close to the main stem of the plant. This way, you deliver straight to the roots and less water is lost through evaporation.

A plastic funnel delivers water well to shallow troughs and alpine pans. The water, which seeps through the bottom of the funnel, is taken up more slowly and comprehensively than if you splash over the whole surface with a watering can.

Bearded iris should be split up and replanted now. Break up old rhizomes, discard the pieces with no leaves and replant the new sections, cutting down each fan of leaves to about 15cm. Plant shallowly so the top of the rhizome is above the ground and can be baked by the sun.

Regular dead heading is important if annuals are to continue to make a show through August. Argyranthemums and osteospermums also respond well to regular winnowing. Trace the stems back to their base or to the point where they have a fresh bud before cutting.

Mildew can be an unsightly summer nightmare. Blue scabious seem particularly prone. Acanthus also looks bad. You can drench plants with fungicide. Or cut them down, water them and wait for new growth.

What to see

This weekend is wildflower time at the Garden Museum in Lambeth (see Cleve West, page 55). Tom Stuart Smith's favourite nursery will be there, selling trays of plug plants for attracting bumblebees or butterflies, greening up a roof or coping with dry chalk. Today and tomorrow (10.30am-5pm) at the Garden Museum, Lambeth Palace Road, London SE1, admission £6. Call 020-7401 8865 or visit garden museum.org.uk.