Jobs For May

Here's a few ideas of what you could be doing this month...

Top Tip - Get climbing

Secure wayward stems of clematis, roses, honeysuckle and other climbing plants to prevent them being snapped in a gust of wind, depriving you of a vertical show of summer flower.

Prune early flowering clematis as the blooms fade - if they have outgrown their space, keep them within bounds by pruning stems just above a leaf joint.

Fill your garden with scent this summer by planting sweet pea seedlings in a sunny spot against a trellis or other supports. If you forgot to sow seeds earlier this year, buy some ready-grown plants.

Bulbs

• Tidy up tulips in beds and pots by snipping off fading heads. Lift out the bulbs in summer, dry on sheets of newspaper and store in a cool, dry place before planting again in autumn.

Beds and borders

• Tidy up worn out hellebores. Cut off flowering stems of stinking hellebore and H.argutifolius at ground level, and dead heading the many varieties of Lenten rose (Helleborus x hybridus).
• Many perennials flop by mid-summer, so make sturdier plants by giving them the Chelsea chop – a technique carried out by nurserymen at the end of the show. Plants, such as rudbeckia, helenium, sedum and solidago, can be cut back by half, resulting in bushier plants that will flower slightly later.
• If you have been extra cautious with exotic or tender plants, now is the time to remove their frost protection. Bananas, tree ferns and palms are now actively growing and fleece or other insulating material will hamper new growth.
• Thin crowded delphiniums, leaving 5-7 shoots on established plants to improve final flowers.

Plants in pots

• Pull up forget-me-nots, wallflowers, violas and other spring bedding plants as flowers fade. Chop them up and add to compost heaps.
• Water plants well in the morning so they have a good supply that will last all day – avoid watering during the day as splashes on foliage can scorch leaves in the sun.
• Mulch the surface of pots with gravel, grit, crushed glass or another decorative material to reduce moisture loss and prevent weeds from growing.
• Move pot-bound shrubs or perennials into larger containers to ensure they grow healthily. Generally, plants need re-potting annually, but check by lifting out of container – if all you can see is a mass of roots, they need a new pot.

Trees and shrubs

• Overgrown or untidy evergreen shrubs? Restore their shape by pruning out any offending branches. Cutting in late spring give plants plenty of time to produce new growth that will ripen before cool weather sets in later in the year.
• For a great display of flower next year, dead head lilacs when the flowers fade. To do this, wait until you see two shoots beneath the spent bloom start to swell, then snip off the flower head just above them with secateurs.
• Lightly prune ribes, pieris and kerria when the flowers fade – cut back lanky shoots and remove any diseased growth.

In the kitchen garden

• Keep rows of raspberry canes tidy by pulling up shoots that are too far away to be tied in easily.
• Sow sweetcorn seeds in pairs, 2.5cm deep and 45cm apart. Water well and after germination, thin each pair to leave the strongest seedling.
• Earth up potatoes once stems are about 22cm tall to prevent developing spuds turning green. Draw up soil, leaving 10cm of growth showing.
• Sow seeds of French beans, cabbage, runner beans, kale, carrots and cauliflowers outside. For summer salads, try radish, salad leaves and spring onions.
• Remove every other fruit on gooseberry plants to ensure those that remain have plenty of space to swell up.
• Keep a close eye out for caterpillar-like, sawfly larvae on gooseberries and currants. Causing rapid and severe defoliation of plants, they can be controlled by spraying with pesticides containing pyrethrum.
• Pinch out tops of broad beans to prevent an infestation of black bean aphid, which is attracted to tender young shoot tips.
• Remove the central flower spike from clumps of rhubarb to ensure the plant continues to produce stems for harvesting.
• Feed tomato plants weekly with a fertiliser high in potash to help the fruit swell. Tie in stems and remove side-shoots as necessary.