Gardener's diary - May gardening

Early support of tall growing plants means the developing growth will hide the canes and is easier than trying to attach supports when your border is in full flower.

Many perennials can now be sown outdoors. These include Delphinium, Lupinus (lupin) and Chrysanthemum maximum (Shasta daisy).

Delphinium cuttings taken in March are now ready for planting.

Mulching should be completed if it was not done earlier.

Any remaining hardy annuals can now be sown. Annuals sown last month should be ready for thinning out.

Prepare a small area to sow biennial seeds that will flower next year. Use a top-dressing of bone-meal, rake the surface and sow seeds in drills 12mm (1/2 inch) deep and 20cm (8 inches) apart.

The last week in May is a good time to plant once the danger of frost is gone and plants are hardened off.

Ensure the ground is weed free and apply a balanced fertilizer and a generous mulch of well rotted manure or leaf mould.

After a period of wet weather is the best time to plant evergreens such as Ilex (Holly).

Tie in new growth and prune any growth which is growing inwards or outwards. Prune Clematis Montana only if the plant is too vigorous. Cut back hard immediately after flowering to encourage new growth.

Keep the area around young trees weed free and ensure that you water regularly during dry spells, making sure the water reaches the roots. Mulching helps retain moisture and suppress weeds and feeding is beneficial to encourage growth.

Complete planting this month, watering the ground well the day before and mixing in peat to retain the moisture.

Temporary windbreaks can protect plants on an exposed site.

Maintain established hedges with regular pruning of extruding branches.

Water from time to time during hot, dry weather using rain water if possible as the lime in tap water may cause yellowing of foliage. Mulch with peat or leaf mould.

Collect ripe seeds from early flowering bulbs and sow them immediately. Tulips may need to be moved to make space for summer bedding. Lift and heel in on a spare piece of ground. When foliage dies down, lift and store the plants until the autumn.

Shading would be provided in alpine houses from this month onwards. Be careful with watering and ventilation to prevent disease.

This is a good time for propagation, collecting seeds and taking cuttings.

Rock garden plants are now at their peak. Keep weeds under control and keep a check for aphids. Water when the top 2.5cm (1 inch) of soil is dry, to encourage the roots to grow downwards. Seed collecting and sowing can be done now as well as propagation from cuttings from new growth.

Lower the blade on the lawn mower and start to mow more frequently. Irrigate the lawn frequently and thoroughly, to a depth of at least 15cm (6 inches).

Apply a light dressing of nitrogenous fertilizer towards the end of the month, mixing it with sandy soil to reduce scorching of the grass from the sun. Apply during cool, damp weather if possible.

Sowing of new lawns can be done early in the month.