Gardening Jobs for the Month of May 

 

“It was the month of May, the month when the foliage of herbs and trees is most freshly green when buds ripened, and blossoms appear in their fragrance and loveliness” – Thomas Malory 

 

Hello,  

May is the month when the real gardening begins, yes there is lots to do, but remember to take time to stop, to look and to enjoy the beauty found in your garden. 

If you are looking for a few gardening jobs for the month, here are “just a few” things to keep you busy. 

Sow half-hardy annual seeds outdoors. 

Spring flowering clematis, such as Montana’s are pruned after flowering, cutting out overcrowded and dead stems. Cut back remaining stems as much as you need to keep the plant tidy. 

Tidy up Clematis Montana once it has finished flowering. 

Prune spring-flowering shrubs once they have finished flowering. 

Hoe over bare ground to keep the weeds down.  

Depending on the weather, plant out tender vegetables once the frosts have passed. 

Tie in early tomatoes and keep feeding them with liquid feed. 

Clear out spring bedding plants from containers to make way for summer bedding plants. It is well worth removing the compost from last year and replacing with new, for containers John Innes potting compost is best as it has soil and does not dry out as quickly as soil less composts.  

Once this year’s polyanthus and primroses have finished flowering dig them up and divide the plants into smaller sections, replanting them in a shady part of the garden to bloom again next year. 

Water and feed containers regularly, as the weather warms watering can become a daily or even twice daily task. Supplement container plants with balanced liquid feed every 2 - 4 weeks to promote healthy growth. 

Thoroughly inspect plants for pests and diseases - early prevention is much easier than curing an infestation. 

Look out for signs of blackspot on roses. If discovered, treat it with a systemic fungicide, I use Rose Clear Ultra, this seems to work very well. 

Continue to weed beds and borders, this reduces your plants’ competition for water and nutrients. 

Lift and divide overcrowded clumps of daffodils and other spring-flowering bulbs. 

Put straw under strawberries to prevent young fruit rotting. 

Sow sweetcorn in blocks to aid pollination and sow root vegetables. 

Earth up potatoes once growth reaches about 25cm (1”). 

Start planting out summer bedding plants towards the end of this month in warmer parts of the country.  

Prune forsythia after flowering -  If you do not do this every year, they quickly get unmanageable and flower less well. Using sharp loppers and secateurs cut a quarter of the old growth to the base. Also remove diseased, dead, dying, and wispy stems cutting them to the ground. Finally prune stems that have just flowered to two buds above the previous year’s growth. 

Plant out dahlia tubers and cannas after all risk of frost has passed, at the end of the month. 

Continue sowing annuals, such as California poppies, into gaps in borders for colour from August into autumn. 

Tie in climbers. 

Mow established lawns once a week now that the grass is growing well, each time you mow lower the mower blades slightly. Try not to be hasty in lowering the mower blades or the lawn will be scalped. This may lead to the lawn turning yellow and cause bare patches.  

Remove faded spring bedding, such as wallflowers and forget-me-nots once faded and add to your compost bin. 

Harden off tender plants raised indoors but bring them back in at night to protect from late frosts. 

Pinch out the shoot tips of bedding plants and young annuals to encourage bushier growth. 

There is no shortage of seeds to sow in the May Garden, with many now being able to be sown straight into the soil outside, sunflowers, cornflowers, zinnias, nasturtiums, nigella, poppies, and wildflower mixes can all be sown directly into beds, borders, or outdoor containers. 

In trays and pots, you can start growing biennials and perennials, such as foxgloves, wallflowers, delphiniums, lupins, and primroses in the greenhouse or on the windowsill to flower next year and years to come. 

In May there is usually a frost or two still to come. If you have planted tender bedding, such as petunias, heliotrope, fuchsias, or begonias, it is best to cover them on clear nights. Sheets of newspaper, or horticultural fleece, will keep them snug if temperatures dip. 

Feeding now will pay dividends later, but you must use a slow-release fertiliser having potash, to encourage more flowers. Vitax Q4 is excellent, and this general fertiliser can also be applied to roses, herbaceous plants, and fruit. Avoid adding nitrogen-rich plant food: it produces too much leaf. 

Vegetables will also respond to enriched soil. The easiest soil enhancer is well-rotted garden compost, so it is worth making your own if you are able to. You can also use well-rotted manure, although spreading it in early spring can be backbreaking. However, you can also buy bagged manure from garden centres. The best way to incorporate organic matter into a vegetable bed is to put some at the base of the planting hole. Squashes and courgettes benefit hugely from sitting above organic material because it aerates and warms the soil. 

In the middle of May, around the time of the Chelsea Flower Show, you can do the ‘Chelsea Chop’: Cutting the stems of flowering herbaceous perennials such as sedums and asters will keep plants smaller and encourage more flowers. This should not be done on flowers which flower only once, or flowers which are intended to be tall and striking. 

Keep an eye on slugs, especially when it has been raining. Indeed, during a rain shower is the perfect time to get outside and find them. 

Weeding: Five minutes here and there (rather than a whole afternoon) with a hand or long hoe saves fingers and backs. 

As well as weeds you will also find self-seeding plants taking off in May. Thin out gluts of self-seeders such as poppies and fennel leaving the strongest where you want them to flower, remembering that its best to keep them from flowering too close to the edges of beds. 

In the flower border any frost-damaged leaves should be pruned back to the next healthy bud or side shoot. Frost damaged plants often recover so do not pull them up but wait until summer, giving them time to regrow. If there is no sign by mid-summer, you can pull them up. 

Time to get rid of any brown or faded material in the borders. Certain plants have already finished flowering and they can be tidied. Deadhead all, or most, aquilegias, because these self-seed far too enthusiastically. 

Start hardening off seedlings of beans, tomatoes and other plants sown indoors or under glass. Allow a couple of weeks for the process gradually acclimatizing the plants. French beans can be particularly delicate so take care not to expose them suddenly to intense winds or rain or scorching midday sun. 

Make a bean wigwam using canes or hazel stems to make a support for growing beans. Either tie the tops together to form a wigwam or else arrange the supports in long Xs that cross either halfway up or close to the top. Sow a couple of beans to each cane and a few at the ends of the row as replacements for any that do not come up. Beans are greedy plants so they will enjoy being grown above a trench filled with rotted manure or kitchen compost (even part rotted will do). Cover the trench with soil and then plant the beans. Once the beans are up, make sure that the slugs cannot get to the growing tips because they will destroy the plant. 

Thin out vegetable seedlings already planted allowing space for individual plants to flourish, wash and use thinning of lettuces and beet tops in salads. 

Check strawberry flowers for frost damage in colder areas, net them against birds and lay down straw under the plants to protect them from rain. 

Liquid feed young plants regularly to keep them growing strongly 

Look after your finished spring bulbs for next year. Once they have gone over, resist the temptation to cut back the foliage. Instead, let it die and break down on its own and add liquid fertilizer all around the clumps. This will give you an even better display next spring. 

Harden off half-hardy plants by leaving them outside during the day and bringing them back under cover at night for 7 to 10 days before planting outdoors. 

Continue dividing herbaceous border perennials to improve vigour and create new plants. 

Divide established clumps of hostas as they come into growth. 

Towards the end of the month, keep an eye out for powdery mildew on flowering shrubs and flowers, like rhododendrons.

Treat with fungicide to prevent further spread. 

Lift forget-me-nots to prevent heavy self-seeding and reduce spreading. 

Prune penstemons now - cutting all the old shoots back to the base, providing there is new growth at the bottom of the plant. If there are no new shoots at the base, cut just above the lowest set of leaves. 

Lightly cut back & tidy up late-flowering honeysuckle. Leave any big pruning jobs until winter. 

Take cuttings of tender perennials, such as fuchsia and pelargoniums (tender geraniums). The new shoots of hardy perennials can also be used for cuttings. 

Take softwood cuttings of shrubby herbs.  

Tie in rambling and climbing roses. Laying the stems horizontally will help to produce more flowers. 

Tie in sweet pea plants with sweet pea support rings to encourage them to climb. 

Cut back flowered shoots of choisya to promote a second flush of flowers in autumn. 

Trim lavender plants, cutting off old flower heads and a little of the current year's growth. 

 

 

As always, I wish you happy gardening  

Rog 

The writer, Rog Leppard, is a professional gardener and gardening writer with his own gardening business, English Cottage Chic Gardening, based in East Wellow, Hampshire.