May Gardening

May is an eventful and exciting month in the garden, plants (and us) love the warmer weather and we can see daily changes as spring bulbs fade and herbaceous perennials unfurl from the ground and swiftly grow.   Chopping back some of these herbaceous perennials in late May will make bushier plants that flower more prolifically and later in the season. This pruning method is known as the ‘Chelsea chop’.

The science part of why it works: The plants become more bushy because the central stem of the plant is dominant (ie grows more strongly than) the side stems this is known as Apical Dominance. By removing the apical bud by cutting back the central and top shoots, the side shoots are able to branch out and compete to become the lead growth. Coppicing and pollarding also makes use of this natural response to damage to direct plant growth and produce a desired shape or size. By careful pruning it is possible to create remarkable topiary designs.

How to carry out the Chelsea Chop: Clumps of perennials can literally be chopped back but one third to a half by using either shears or secateurs. If you have several clumps of one plant, try cutting back a few but leaving others, this will prolong the overall flowering time. Another method is to cut back half of the stems at the front of a clump this will extend the flowering time rather than delaying it. In addition the growth that has been cut off can be used for cuttings.

Most Daisies including: Anthemis, Rudbeckia, Aster, Echinacea, and Helenium all respond well to the Chelsea Chop.  As do Sedums, Phlox Paniculata, and Nepeta. It also works on plants that have already flowered such as Pulmonaria, Brunnera, and perennial wallflowers. As long as the plant hasn’t set seed, a new flush of green leaves and hopefully another crop of flowers will soon follow.

Do be careful though, not all herbaceous plants respond to cutting back, and you could loose the flowers for one year. These are mainly plants that only flower once such as Peonies, Iris and Aquilegia, or spire-forming plants. Some plants do not produce side shoots, such as alstroemeria, and these too should not be chopped.

Using this method along with regular feeding and watering ensures beds and borders look tidy throughout the summer.

As well as doing the Chelsea chop, here are a few other jobs to do in May:

1. Earth up potatoes, and promptly plant any still remaining
2. Collect rainwater and investigate ways to recycle water for irrigation
3. Regularly hoe off weeds
4. Open greenhouse vents and doors on warm days
5. Mow lawns weekly
6. Check for nesting birds before clipping hedges
7. Lift and divide overcrowded clumps of daffodils and other spring-flowering bulbs

As a final note, beware of frosts. There is always a last frost in late May that catches us all unaware. Keep vulnerable plants and new shoots protected at night if frost is forecast.

Rachel Sobiechowski BSc (Hons) P&R Garden Supplies, Fengate Drove, Brandon                 01842 814800   www.p-rgardensupplies.co.uk