Top jobs for May

By Tony Jepson MCI Hort FdSC
•
20 Jan, 2022

Maintenance

Mow regularly

Maintain a 3in gutter around the lawn edge. This will prevent grass from creeping into the border.

Prune out any frost damage on evergreen shrubs.

If not already done so (and depending on local climate) Cut back tender shrubs such as Penstemon and Fuchsia after the danger of frost has past.

Trim evergreen hedges to keep them neat. Evergreens such as Viburnum tinus can also still be trimmed this month. (check for nesting birds first).

Prune spring-flowering shrubs such as Berberis, Choisya and Ribes after they have finished flowering.

Prune overcrowded or dead stems of Clematis montana once it has finished flowering – don’t worry it will take even hard pruning very well.

Late spring is a good time to coppice or pollard (cut back hard) Eucalyptus.

Tie in climbing and rambling roses as near to horizontal as possible to restrict sap flow and result in more flowers.

Remove any reverted green shoots on variegated (leaves with two colours) evergreens, to prevent them reverting to a single colour.

Put supports in place now for tall herbaceous plants or those with heavy blooms before they are too tall.

Plant out cannas and dahlias when danger of frost is past.

May is a good time to divide herbaceous perennials that you want to propagate or that are getting too big. Dividing will also help the plant to produce new growth. Bamboos can be divided in the same way.

Divide hostas as they come into growth.

Cut back clumps of spring-flowering perennials such as Pulmonaria and Doronicum to encourage fresh foliage. This will keep the plants size in check and flower better next year.

Divide primroses after flowering and plant them in a nursery bed until they are ready for planting out again in the autumn.

Remove faded wallflowers and spring bedding from beds and pots to make space for summer planting.

Check pot plants for signs of being root bound.

Deadhead tulips and daffodils but allow the foliage of daffodils and other spring-flowering bulbs to die down naturally rather than tying in knots.

Hoe regularly between rows on hot days to make sure the weeds dry up and die.

Mulching around the base of your plants will help them to retain moisture around the roots.

Keep pots and hanging baskets well watered using collected rainwater wherever possible.

Planting

Plant out summer bedding at the end of the month.

Propagation

Take softwood cuttings of deciduous shrubs such as Forsythia, Fuchsia and Hydrangea.

Take softwood cuttings of tender perennials to propagate your favourites.

Treatments

Apply a high nitrogen summer lawn fertiliser to encourage a healthy-looking lawn. If moss is a problem, choose a combined fertiliser and mosskiller when feeding the lawn. A selective lawn weedkiller will kill the weeds but not the grass.

Apply a liquid fertiliser to spring bulbs after they have flowered will help prevent daffodil blindness and encourage a good display next year.

Landscaping

Sowing new lawns or over-seeding dead patches can still be carried out in early May while the ground is moist.

Apply shade paint to the outside of the glass or similar measures to prevent temperatures soaring in your greenhouse on sunny days.

Use a pressure washer to remove algae from paths. An algae killer may help. Organic options are available.

- Remove dirt and algae from walls, paving and patios.

Repair pergolas, arbours and arches as necessary.

If the weather is dry you can treat fences, sheds etc with wood preservative and stain.

Collect rainwater for irrigation.

Pond care

Divide and plant waterlilies if not done last month.

Thin out, cut back or divide excessive new growth on aquatic plants.

Clean out pond filters

Plant any new aquatic plants you fancy this month.

Fish will need feeding - a little and often is best.

Continue to remove blanket weed.

Thanks as usual to The Gardeners Guild for use of their tips this month.