- PROVIDING support for herbaceous perennials and climbers is a key operation in our mixed borders. Staking should start when the new growth has just started - ideally when it is 6- 8in (15cm-20cm) tall. Where possible, we use birch pea-sticks harvested this year.
- For large plants, use coppice stems at least 0.8in (2cm) in diameter. Make three or four holes around the plant with a metal bar, then push the stems in and firm the soil around them. Weave the pliable branches to form a cone-shaped support structure.
- Summer-flowering shrubs such as buddleja and hydrangea can now be pruned.
- Buddleja davidii (butterfly bush) should be pruned to a woody framework 6in-12in (15cm-30cm) high. Cut back to leave two or three pairs of buds.
- Prune last year's flowering branches of mop-head and lacecap hydrangeas and Hydrangea macrophylla, because these flower on last season's wood. Trim to a pair of fat buds.
- Hydrangea paniculata flowers in late summer on this season's growth. It can be cut back annually to a woody framework as low as 1ft (30cm).
- Dead-head pieris so they do not become biennial-flowering.
Cucumbers and melons
- Cucumbers and melons are often overlooked as plants for the vegetable garden. They need the warmth of a greenhouse or conservatory to start with, but should fruit well after being planted out in May.
- Using multi-purpose compost, sow two seeds into the centre of a 4in (9cm) pot, ensuring that they are covered by .5in (10mm). Water in and place in a heated propagator at 20C.
- The seedlings will germinate within a week. Thin to the strongest in each pot, and grow them in a warm greenhouse until ready for planting out.
- Sweet peas are one of the RHS's long-term trials. Young plants sown in January and kept in cold frames are now ready for planting out. But seeds can also be sown now, and these should provide blooms in summer.
- To improve germination, carefully nick each seed with a penknife, removing a small piece of seed-coat opposite its eye. Do not soak the seeds, since they rot easily. Sow in sweet-pea tubes using a multi-purpose compost. Keep them at about 15C until they germinate, and plant them out in May.
- Naturalised bulbs in grass do not need much attention, but do dead-head them. This helps keep the bulbs healthy.
- Regular removal of faded blooms extends the season and improves the vigour of the bulbs. After flowering, pinch through the stems just below the seed-head.
- Early-flowering bulbs such as narcissus need to be left unmown until at least six weeks after they flower, or until the foliage is turning yellow. Otherwise, the bulb will not have stored enough energy to flower well again next year.
- With thanks to the team at RHS Wisley (01483 224234; www.rhs.org.uk/wisley).