Jobs to do in the garden in May

Tips and advice from Sheena Marsh on making the most of your outdoor space this month

With all the freshness of spring and the promise of summer to come, many gardeners regard May as one of the best months in the garden. Make the most of May’s warmer weather to start getting ready for the summer months. Just taking a leisurely stroll through a garden can lift the spirits. It’s a great time of year to visit some of the many gardens that will be opening up to the public to glean ideas and inspiration.

Between visiting flower shows and other people’s gardens, there’s plenty to do in your own. You can now begin harvesting the first delicious early vegetables, planted out earlier in the year. To guarantee a regular succession of young vegetables throughout the summer months, sow seeds at weekly intervals so you don’t get a glut all at once. Although it’s a bit of a chore, hoe in between plants and vegetables as the weeds start to spurt in the warmer weather. Keeping on top of the weeds at this time of year will pay off in the long term. 

Plant summer bedding

A wide variety of summer bedding plants are now available to buy from nurseries and garden centres. However, if late frosts are forecast, those tempting tender geraniums and other non-hardy annuals are best left to plant out until about the middle of the month. Containers can be planted up with summer bedding plants from about the middle of May. It’s worth removing the old compost if it has been in your container since last year. The new compost will give your plants a better start. Add water retaining granules and slow release fertiliser to keep the container fed all summer.

Remember containers dry out very quickly so if you’re planning to keep a dazzling display going for the whole summer – keep watering or set up and irrigation system.

Trim evergreen hedges

Lightly trim formal evergreen hedges, such as box, even if it hasn’t grown very much yet. Box doesn’t take kindly to being cut back hard, so the sooner its trimmed the better it keeps its shape. Although it takes more time, this job is best done with hand shears, as opposed to a mechanical cutter, for a better finish. You can also take cuttings from any shoots about 8cm (3 inches) long. Trim each cutting just below a leaf joint, pot into cuttings compost, cover with clear polythene and leave to root in a shady corner of the garden. In a few weeks they should have rooted so you can pot them up to plant in another part of the garden.


Prune spring flowering shrubs once they have finished flowering. Examples are things like Kerria Japonica, Forsythia, and Spirea. Also, if you have one, prune the glorious Clematis Montana after it has flowered. This beauty is a very fast-growing climber that can easily get out of hand unless pruned hard every year. It’s a good choice of plant if you have an ugly wall or fence that you want to cover quickly. Finish planting new shrubs if you possibly can this month, before it gets too dry.

Continue to deadhead spring flowering bulbs that have gone over, this allows the bulb to store up more energy to produce flowers next year. You must leave the foliage intact for at least 6 weeks after flowering, but simply snap off the flower heads with your fingers or a pair of secateurs. Use a general organic fertiliser around the base of the bulbs to encourage the development of new flowers for next year.

Lawn care

Feed and weed lawns during this month and be sure to mow them regularly from now on. Mowing is the best way to ensure you have a good lawn. Once a week is about right. Don’t apply weed killer either just before mowing or just after as the weeds need to be actively growing when they are treated.

Treat weeds such as dandelions in your lawn with a selective weed killer. This is the best month to do this as the weeds are now actively growing. We use a product called ‘Verdone,’ which is a liquid weed killer and the most economical way of treating large areas of lawn. Follow the manufacturer's instructions and only treat the areas that are affected. It will not damage your grass if used according to the instructions. Finish sowing or laying new lawns this month before the weather becomes too warm and dry. The best time to sow new a new lawn from seed is spring and autumn while the ground is still generally warm and moist.

Start pruning trained plums and cherries particularly if you are growing them against a wall or fence as espaliers or fan-trained trees.

Sheena’s plant of the month

Clematis macropetala ‘Markham’s Pink’

Really spectacular, double, candyfloss-pink, early spring flowers with creamy-yellow centres, are followed by silvery, seed heads, which are retained throughout the summer. This clematis looks lovely scrambling through a strong tree or shrub. Ideal for a north-facing site, it's also known as the downy clematis since the new shoots are covered with down. I think this is one of the best early flowering Clematis and there’s usually a spot for it to fit in most gardens.

Sheena Marsh is the founder and a director of Oxford Garden Design. For over fifteen years she has worked closely with hundreds of individual garden owners to produce practical landscape plans that result in gorgeous gardens.

For more information on the gardens that Sheena and her team have designed in and around the Cotswolds - and to get in touch - simply visit

Images: Oxford Garden Design