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May in your garden

Helen Penrose checks off the key jobs coming up in your garden

May priorities

Make the maincrop sowings that can’t be put off any longer: potatoes, onions, peas, carrots and beetroot.

Make at least one sowing of your favourite salad crops; it’s all too easy to think that April sowings will cover it and be left with nothing to harvest by mid-July.

Thin, weed, water, and provide support for the sowings you’ve already made.

Pot bound plug? Don’t let your seedlings get pot-bound. As soon as they reach transplantable size, plant them out – or, if the weather suggests that that isn’t a good idea, pot them on.
PICTURE: Mike Clark

May is a busy month, and one when anything seems possible – but don’t forget that it is still spring, even if the warmer days make it feel like summer. It’s too early to plant out tender crops in most gardens. You can get caught out by a late frost right up to the end of the month, and cold winds and heavy rain can do almost as much damage.

The good news is that there’s still time to make successful main season sowings. If April got away from you, don’t panic; make your main sowings and plant your potatoes and onions in the early days of May, and you’ll still get a good crop, albeit a slightly later one.

Plan crop rotation

Ornamentals

Plant out hardy annuals raised in trays, and sow more seed among the transplants to provide follow-on colour.

Only plant out tender annuals once you are sure that there will be no further frosts; June is safer unless you have a very sheltered southerly garden. Ignore those tempting displays of tender bedding plants in the garden centres until you are sure you can safely put them in the garden. Whether home-grown or bought-in, harden off tender plants by putting the trays outside on fine days for a week or so before planting them out.

Thin direct-sown and self-sown seedlings; you’ll get a much better display if you are ruthless.

Sow seed of hardy perennials in a nursery bed.

Spring-flowering perennials can be lifted and divided as necessary this month.

Stake tall perennials now, before they need it, and tie in climbers as they grow.

Put supports in place for sweet peas and other annual climbers.

Pots & Patios

Anything in a pot or container will need regular watering, particularly if it is windy. Other than that, save the watering (and the water) for later in the year.

Keep tender plants in pots

You can safely put out tubs and hanging baskets containing tender plants in the second half of May, since with containers there is always the option of a strategic retreat back under cover. PICTURE: Dave Bevan

Lawns

Mow your lawn little and often. The cuttings are invaluable as a mulch around your vegetable crops, but if you have more cuttings than you need they might as well stay on the lawn from now on; they will feed the grass and help it to retain water.

Don’t mow areas of lawn where bulbs are growing until six weeks after the flowers have finished.

If you are planning to lay or sow a new lawn this year, do it now or wait until autumn, particularly if you live in a drought-prone area.

Vegetables

Sowing & planting

Hardy crops can be sown straight into the garden this month. However, if you can cope with the extra work of starting the seeds in pots or trays, they will get off to a stronger start, and you’ll avoid losses to slugs. It also means that you can plant out ahead of schedule if the year turns out to be mild, or pot on your seedlings and keep them under cover if the spring is unexpectedly cold.

Maincrop potatoes should be planted as soon as possible. If you don’t get round to it until the second half of May, you will do better with a quick-cropping ‘early’ variety.

Any remaining onion sets should go in at the beginning of May.

Sow maincrop carrots in the first half of the month. After mid-May, you will do better with an early, short-season variety. Cover your crop with fleece from the outset to thwart carrot fly.

ake successional sowings of salad crops, sowing a short row every two or three weeks.

Sow main-season crops like beetroot, kohlrabi, spinach, chard and turnips.

Broad beans can still be sown in May to give you a late summer crop.

Sow your maincrop peas – or make a second sowing to extend your harvest.

Sow French and runner beans in deep pots under cover – or sow them straight into the garden, ten days or so before the last likely frost date for your area. This should mean that by the time they germinate they will be out of danger. Slugs can graze off emerging beans before you even see them, so if your garden is slug-infested, sow in pots.

Kale and calabrese can still be sown at the beginning of May.

It’s time to sow winter cabbages and winter caulis – and don’t forget about sprouting broccoli; with last year’s crop just having finished it’s difficult to believe that it needs to be sown already, but it does.

Sow sweetcorn and cucurbits (courgettes, marrows, summer and winter squashes, pumpkins and outdoor cucumbers) in individual pots under cover. Alternatively, wait until mid-May in the south or the end of May in the north and sow these crops straight into their cropping positions under jamjar or plastic bottle cloches.

For more advice, see this issue, available to buy online!