Friday, 24 February 2012

Cutting back perennials - The case for delay.

The dried stems and seed heads of last year’s perennials are finally getting the chop. Perhaps this may seem scandalously tardy to some, but I would rather leave the drifts of perennials to age, for the most part, gracefully through the winter than spend months looking at drab patches of bare soil waiting for spring bulbs to show.

The Upper Deck in February. Miscanthus 'Yakushima Dwarf' and Monarda 'Scorpion'. 

I leave the skeletal stems as long as I possibly can, until their ragged untidiness gets to me, which is probably way longer than those of the neat school of gardening could tolerate. Through the autumn and winter the shriveled blooms and stems are given new charm as they shimmer when caught by golden winter sunshine and sparkle fleetingly when encrusted by frost. The swathes of straw like stems, fluffy seed heads and delicate framework of umbellifers look fantastically appropriate to the season - it is second glorious bite of the cherry. The plants that provided a colourful pageant through the summer go on to deliver a quite different, muted, but no less splendid display, through the colder months. Wildlife benefit too: the deft gymnastics of a goldfinch swinging on slender stems to get at seed heads is prize enough but insects benefit too I think. 
Some plants seed heads are more attractive than others and the ghosts of some perennials and grasses are more robust. When I plant now I now try to imagine my schemes not only in the summer but how it will look in the autumn and winter too. Plants will stay in best shape in sheltered gardens. In  areas whipped by savage winds or really damp spots toughies like teasels and verbascums have the best of remaining upright.

Achillea 'Walter Funke' in February after frosts and snow.

My favourite plants which stand well:

Telekia speciosa
Perovskia (Russian sage)
Verbena bonariensis
Lunaria annua
Molinia (beautiful until early winter then flops)
Aquilegia (ladies bonnets)
Monarda (bergamot)
Nigella damascena (love-in-the-mist)
Digitalis purpurea (Foxgloves)
Papaver somniferum (opium poppies)
Echinacea pupurea
Dipsacus fullonum (teasels)
Foeniculum  (fennel)

There are practical advantages to leaving the cutting back until late winter. The first is you know where plants are. Pretty basic stuff, but if you are planting bulbs, adding new plants, weeding or applying mulch, it helps. Secondly, the old growth provides a protective tangle over new soft growth as spring approaches. Finally, you get masses of plants for nothing - no work required, no money changes hands. I love this bit, the plants set seed and these are distributed naturally through the beds and tiny plants spring up bolstering planting, replacing those perennials which have a short life. In this way the planting becomes dynamic and interesting, a self generating colony where some types of plant will thrive and others will dwindle. Those most suited to your patch will thrive. At some point you may decide to intervene to redress the balance by removing some seed heads or organise the chaos by moving plants, but allowing nature to take at least some control will reduce your workload and spend. This also saves the environmental costs of buying in plants raised in a nursery - all excellent reasons to leave seed heads alone and weed carefully preserving young seedlings. Thrift and time-saving, brilliant.

How about the downside of cutting back late? Well, if you dally too long plants will start growing apace making cutting back more challenging as you try to snip around the new growth. Seeing the beauty might be a problem for some, choosing plants that have a sturdy framework helps, as does smartening -up a bed by taking out plants as they become too tatty for you to tolerate rather than waiting for one epic session of cutting back.

The task of cutting back large tracts of planting can be back breaking and leave you with an aching hand, from which the secateurs have to be prised . The large Miscanthus like ‘Grosse Fontaine’ can be a real challenge to cut back in any number so now, after a tip from a landscaper, I fell them with a petrol hedge trimmer. There are probably lots of reasons why this is not the best method, but it works.

Having enjoyed some of these plants for seven or eight months the process of cutting them back is just about finished. Once I have cleared the old growth, I weed and spread a layer of mulch. The beds look rather bare but spick and span and ready for spring.  

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