Whatton House Garden: The Chelsea Chop and Hampton Hack
Pruning is normally associated with woody plants such as renovating shrubs or removing the lower branches from a tree. But there are also some pruning tasks to be done in the herbaceous border to keep it looking at its best. The more time devoted to these pruning techniques the better the overall performance will be. In some cases, pruning perennials can save time in other ways such as reducing the need to stake tall stems and reducing the amount of self-seeding which results in less weeding.
One of the most well know pruning techniques for herbaceous perennials is the Chelsea Chop. It is normally done around the time of the Chelsea Flower Show. It can achieve two things. Firstly, it is used for height control by making the plant shorter and bushier. This does however mean smaller but more numerous flowers. By making the plants more compact the need to use plant supports is greatly reduced. The other result of the Chelsea Chop is delayed flowering by one-three weeks depending on the species. So, if half the plants of a given species are cut back it is possible to extend the display by another week or two. A summer flowering phlox such as P. maculata ‘Alpha’ can be cut back by half when in bud in early June. It may now flower at 18in/45cm rather than at 2.5ft/ 76cm and about two weeks later than usual. Balloon flower (Platycodon grandiflorus) tends to flop but pruning it back by half in early June can produce plants 1-2ft (30-60cm) shorter than normal and with a 2–3-week delay in flowering. You can cut a whole plant back by half its height, every other stem, or just the back half. If you have a group or drift of a given species, it is often easier to cut back individual plants to extend the flowering season.
Perhaps not so well know is the Hampton Hack. This is used to freshen up spring and early summer flowering perennials. It should result in a new flush of foliage and often a second round of flowers. It is often done at the time of Hampton Court Flower Show (early to mid-July). Plants can look tired after flowering and often benefit from being cut back. It is usually best to cut down to the start of new growth developing at the base of the plant, or the basal foliage. If cutting back to the ground, do not cut level with the soil; leave about 2 in. of stem, just in case new buds are present slightly above ground.
The Geranium endressii ‘Wargrave Pink’ is a case in point at Whatton House. Sprawling, straggly stems tend to develop after the initial flowering. After being cut back the plants usually fill in with fresh mounds of foliage within two weeks. Sporadic rebloom often occurs as well. Astantia major can look tatty in a dry summer with yellowing foliage, so it often looks better cut back to new growth. Otherwise cutting back flowering stems maybe enough to smarten the plant up. Deadheading can prolong flowering into September and prevent excessive self-seeding. Some people have success with cutting back oriental poppies after flowering to encourage new but smaller growth that remains to the fill the space through the summer.
The above techniques combined help to keep the garden looking fresh through the summer and keep the flowers coming. Sharpen your secateurs and get pruning!
William Stanger of Four Winds Horticulture is a local Garden Consultant and international writer. He is advising Whatton House on the garden’s regeneration. He has worked at various gardens in the U.K and New Zealand including The Savill Garden and Dunedin Botanic Garden. He has a M.A. in Historic Designed Landscapes and a BSc Hons in Green Space Management.