What to do
* As the weather warms up, greenhouses will need more frequent damping down. High humidity helps flagging plants, but also discourages red spider, which is a difficult pest to eradicate once established. Artificial shading, with blinds or a glass wash, may also be necessary on greenhouses in full sun.
* Check for greenfly on roses and other known targets. Ladybirds are now active, so if you must spray, use an insecticide designed for aphids.
* Sow Shirley poppies, love in a mist, eschscholzia, clarkia and cornflower where there are gaps to fill. They will be late into flower, but better than bare soil. Rake the soil carefully first to make a fine tilth and firm the ground with the back of a rake before sowing seed. Cover very lightly with earth. Cats love new seed beds. So do sparrows. If either are likely to invade, cover newly sown seeds with wire netting or twiggy sticks.
* Finish hardening off bedding plants grown inside from seed. Gardeners in the south may already have risked planting out tender bedding. It is a gamble worth taking.
What to see
* Tom Stuart Smith is one of the most brilliant garden designers in Britain; he's already running out of fingers on which to count his Chelsea Gold Medals. A major exhibition of his work opens this week at The Garden Museum, Lambeth Palace Road, London SE1. For more information, visit the website, gardenmuseum.org.ukReuse content