Weekend Work: Dampen down the greenhouse

What to do

As the weather begins to heat up, greenhouses need dampening down. High humidity discourages red spider which is a difficult pest to eradicate once it is established. Artificial shading, such as Coolglass, may also be necessary on greenhouses in full sun.

Cordon fruit trees, like espaliers and fans, have a habit of throwing out shoots where you do not want them. Pinch out any that are pointing towards the wall or that are too close together.

Check for greenfly on roses and other known resting places. Ladybirds are now active, so if you spray, use one specifically designed for aphids.

Sow Shirley poppies, morning glory, love-in-a- mist, night-scented stock, eschscholzia, clarkia and cornflower outside where they are to flower. Rake the soil carefully to make a fine tilth and firm it with the back of a rake before sowing. 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.

What to see

The Chelsea Flower Show opens this week in the 11-acre grounds of the Royal Hospital, Chelsea, but entrance is by ticket only. The first two days of the show (Tue and Wed) are reserved for RHS members. Public tickets for Thur and Fri cost £43 (8am-8pm), £24 (3.30-8pm) or £18.50 (5.30-8pm); on Sat the show closes at 5.30pm and all-day tickets cost £43. The big sell-off of show plants starts at 4pm on Sat. To book, call 0844 209 1668 or go to the website, rhs.org.uk/flowershows