May gardening tips

A Late-May Border

27th April – 3rd  May is National Gardening Week

There is nothing more rewarding to most gardeners than to see healthy, vigorous plants in their garden. BUT there are some plants that thrive too well and start to ‘take over’.  In my garden, primroses have been a joy, but when they are seeding into the vegetable plot and into the lawn, they become weeds; similarly, Japanese anemones, the yellow flowered, variegated Lamium galeobdolon and even Camassia quamash can take over and squash less vigorous plants.  I even have Dutch irises and tulips which are proliferating to an embarrassing extent.  These all love a light, well-drained soil.

There is a perfect answer. Share and swap with other gardeners who may be populating a new garden or have less success.  Unfortunately, until the current pandemic has been resolved and social distancing relaxed, we cannot hold plant swaps at the trading shed on Saturdays.

Here are some jobs for you to consider in your splendid isolation!

Kitchen garden

  • Earth up potatoes when the foliage reaches 23cm/9in to prevent green tubers or, if frost is expected, cover smaller sprouts with soil for protection.
  • Sow carrots, radishes, beetroot, lettuce and spring onions for successional harvesting.
  • Harden off courgettes and squashes that were started under glass and protect with cloches or fleece if cold nights are forecast
  • Start to harvest asparagus spears
  • Direct sow French beans and sweet corn.

Ornamental garden

  • Prune overgrown Camellia to young side shoots which will flower next year.
  • Prune Forsythia and Philadelphus as flowering finishes
  • Remove a third of old wood on Spiraea to open up the bush
  • Dead head Rhododendron to make room for new growth
  • Plant out Dahlias and Cannas
  • Dead head spring bulbs but LEAVE THE LEAVES to feed the bulbs until they die back. If daffodils did not flower well, lift and divide the clumps.
  • Take soft wood cuttings of Fuchsia, Anthemis, pelargonium and verbena.
  • Support tall and heavy-headed perennials with pea sticks or special supports
  • At the end of May, do the ‘Chelsea chop’ on late flowering herbaceous plants like sedum (Hylotelephium) that tend to flop outwards. The flowers may be later but they will be sturdier. Other suitable plants are Chrysanthemum, Helenium, Helianthus, Monarda, Phlox, Rudbeckia and VeronicastrumDo not chop lupins, irises, paeonies, acanthus or


Places to visit this month

Most gardens will have cancelled opening, but some RHS partner gardens have posted video tours via facebook.