Gardening jobs this month: May

From Country Living gardening editor Stephanie Donaldson:

Garden care
● Keep young plants growing strongly by liquid feeding regularly.
● Divide overlarge waterlilies and replant in aquatic compost.
● Divide agapanthus.
● Keep tying in sweet peas and use plant rings to prevent them flopping as they grow rapidly.
● Remove suckers from shrubs and fruit trees by cutting them away below ground level. A thick mulch will discourage regrowth.
● Pinch out the growing tips of young plants to encourage bushiness.
● Pinch out lateral shoots on grapevines, two leaves beyond a good flower truss, to keep compact and limit foliage growth.
● Transplant autumn-sown annuals into their flowering positions.
● Take softwood cuttings of favourite herbs.
● Deadhead azaleas and rhododendrons once they have finished flowering.
● Tidy up or cut back Clematis montana once it has finished flowering.
● In hot weather, shade greenhouses and cold frames to prevent plants scorching; water the paths in the greenhouse to cool the air and keep the atmosphere humid.
● Mulch your borders by the middle of the month
● Harden off young plants gradually by putting them outdoors during the day or leaving greenhouse doors and windows open.
● Clear containers for summer displays. Bulbs can be moved to a trench in the garden to allow them to die back naturally before storing.

Insects and pests
● Discourage aphid infestation using a strong jet of water.
● Treat persistent problems with biological controls or organic insecticides.
● Net brassicas to keep off cabbage white butterflies

Fruit and veg
● Sow root vegetables, leaf vegetables and sweetcorn - always sow sweetcorn in blocks rather than rows to assist pollination
● Plant out globe artichokes in rich soil, allowing a metre square for each plant.
● Greenhouse tomatoes are growing rapidly. Tie them in and liquid feed regularly.
● Remove runners from strawberry plants if they are not needed, to keep parent plants growing strongly. Read more on growing strawberries
● Move citrus trees to a sunny sheltered spot outdoors for the summer.

Pruning
● Trim alpine plants such as aubretia and alyssum after flowering to keep them compact.
● Prune standard and topiary bay.

Planting and sowing
● Once all risk of frost has passed, plant out and stake dahlias.
● As the soil warms, start to sow half-hardy annuals outdoors.
● Sow maincrop root vegetables and autumn brassicas. Plant out courgettes and tomatoes.
● Sow morning glories in fibre pots to avoid later root disturbance. Soak seeds before planting.
● Move citrus trees to a sunny sheltered spot outdoors for the summer.
● Harden off young plants gradually by putting them outdoors during the day or leaving greenhouse doors and windows open.
● Clear containers for summer displays. Bulbs can be moved to a trench in the garden to allow them to die back naturally before storing.
● Sow pumpkins and squash seeds directly into prepared beds and cover with fleece until the risk of frost has passed

In the greenhouse
● Position supports and then plant young tomatoes in greenhouse beds or grow bags
● Sow French beans in individual pots ready for planting out next month

From Prima gardening expert Ann-Marie Powell:

● May is a busy month for vegetable sowing, as most vegetable seeds can be sown outdoors. Stagger the sowings so you have crops over a long period.
● Choose strong, healthy bedding plants to add to windowboxes, hanging baskets and containers.
● Prune lavender back hard, but never cut into old wood. Read how to take lavender cuttings
● Sow climbing French beans, courgettes, cucumbers, leeks, runner beans, squash and sweetcorn direct into soil.
● Cut any runners that have sprouted on strawberry plants because they weaken the main plant, and pot them on to form new plants. Read more on growing strawberries
● Sow a little basil, coriander and parsley seed every fortnight to enjoy continual supplies.
● Prune shrubs that have finished flowering, including kerria, forsythia and spirea.
● Prune overgrown Clematis montana before it gets too out of control.
● Thin out hardy annuals as necessary.
● Keep pond weeds in check.
● Give large aquatic plants a feed by pushing slow-release fertiliser tablets into the soil.
● Keep an eye on roses and treat them as soon as you see a pest or disease.