What to do in the garden in May

May is one of the most delightful months in the garden. Days grow warmer and longer, and summer is on the horizon. At this time of year, foliage and flowers are fresh and colours are particularly vivid. 

Trees and shrubs

May is the ideal time to take softwood cuttings from shrubs such as hydrangea, philadelphus and forsythia. You can also propagate these plants by layering, encouraging roots to form on shoots which are still attached to the parent plant.

Use soft twine to tie climbing and rambling roses to supports. Tying branches along the horizontal reduces the flow of sap, thereby encouraging more side shoots to grow, which will bear more flowers. 

Once shrubs such as berberis, ribes and choisya have finished flowering, it’s a good time to prune them. 

Fruit trees will benefit from a light feed as fruit begins to develop.

Perennials, biennials and annuals

From the middle of May, provided unexpectedly cold weather has not been forecast, you can start to plant out tender bedding plants. If in doubt, wait until the end of the month to plant out, just to make sure that young plants are not damaged by late frosts. Fill hanging baskets and containers with a selection of plants for a welcome splash of colour by your front door and on your patio or decking.

Don’t forget to add fragrance to your garden, particularly around your seating areas, with plants such as honeysuckle, lilies and stocks. Watch out for the dreaded lily beetle, a bright red creature which will wreak havoc with your lily plants, given the chance. The scarlet beetles are easy to spot and remove by hand, but you will need to check your plants thoroughly and frequently to keep the pests at bay. 

It’s time to put in supports for sweet peas and other annuals. Annuals tend to grow taller in rich garden soil than they would in the wild, so many of them will require support. Hazel twigs make an ideal choice, as they are very flexible, and they also blend in well with surrounding plants. 

Vegetables and fruit

There are still lots of jobs to be done in the fruit and vegetable garden at this time of year. Many are quickly done, but will make all the difference to your crops. Earth up potatoes as the stems start to emerge above the soil. Put in a framework to support peas and beans. You may also choose to protect peas with netting to prevent the pea moth from laying its eggs on the plants. Ridge up asparagus and keep it well watered. Remember not to cut any asparagus at all in its first year, as this will allow the plant to build up reserves for future years. Your patience will be rewarded with more generous crops once you are able to cut a proper harvest in the third season. 

Harden off celery seedlings and plant them in prepared trenches. Thin out carrot seedlings and if you made very early sowings, you may even find some carrots ready to harvest now. Brush the soil away from the top of the carrot and if the diameter is at least ¾ inch, the carrot should be ready to harvest. 

There’s still time to sow vegetables such as beans, beetroot, cabbages, carrots, cauliflowers, courgettes, cucumbers, pumpkins, spinach and turnips. Soaking beans in water for several hours before planting them straight into the soil can help to speed up germination. 

With so many tender seedlings growing, it’s essential to tackle slugs and snails before they wipe out several months of gardening work overnight. Natural methods of slug control are better for the environment and safer if you have pets. Sprinkle sharp materials such as grit, conifer needles or egg shells around tender plants to deter slugs. Egg shells offer the extra benefit of adding nutrients to your soil. Another option is to use beer traps, which you can make out of a plastic plant saucer or buy ready-made from garden centres. Copper tape positioned around the rim of patio containers can deter slugs from destroying tender plants inside. If all else fails, you may need to resort to chemical slug pellets. 

Lawn care

By now you should be mowing your lawn once a week, and possibly more often if the weather conditions are encouraging rapid growth. Regular mowing is the best way to keep your lawn healthy. If the grass is too long when you mow, you risk damaging it, leaving earth pockets where weeds and moss can take root. It’s also important to make sure you position your mower blades at the right height to avoid scraping the earth and creating bare patches. 

Small uneven patches in your lawn can easily be addressed by sprinkling a small amount of sifted soil into dips or grooves. Avoid using too much soil as it’s important not to smother the grass. If weeds are becoming a problem in your lawn, May is a good time to use a weedkiller treatment. 

Other bits and bobs

If you are growing lots of soft fruit, you will need to protect it from birds. You can use netting supported by poles, but a more permanent solution is to install a fruit cage. Whether you choose to buy or make one, the important thing is to allow plenty of space inside. Bear in mind that you will need to access the fruit canes and bushes frequently to harvest the fruit, so you need the top of the cage to be suitably high.

As the weather is often drier in May, it’s a good time to get on with some hard landscaping projects. If you enjoy outdoor entertaining in the summer, you might want to add some permanent seating features and perhaps a brick barbecue. Brick barbecues are simple to construct and save you the trouble of having to move a mobile barbecue in and out of storage. Even someone with no experience of bricklaying can tackle a small project like this in as little as a day. 

Planning ahead

It may seem strange to be thinking ahead to autumn when summer hasn’t quite begun, but taking the time to sow seeds now will ensure you have a good selection of vegetables for the winter. When you tuck into your leeks, sprouts and swede at the end of the year, you’ll be glad you made the effort to plan ahead in May. If you need more seeds for your winter crops, order them now so you have plenty of time to sow them. Alternatively, if you find yourself short of time, you might prefer to order plug plants, which will be delivered at the right time for planting out.