Sharon Farnham at Headford Garden Design, Taunton, Somerset; expert in garden design and landscaping
Sharon Farnham at Headford Garden Design, Taunton, Somerset; expert in garden design and landscaping

Sharon Farnham at Headford Garden Design, Taunton, Somerset; expert in garden design and landscaping

Headford Garden Design, Taunton, Somerset; consultation, garden designs, project management, landscaping.

The nicest thing about the rain is that it always stops. Eventually. - Eeyore

Let's talk about weeding

February 2019

Iris chrysographes

Dark flowers

An unseasonably warm February has given me the chance to get ahead on all the spring jobs that I usually start in March. I have had three blissful uninterrupted days or pruning, weeding and tidying. I even managed to sand down and repaint the crazy blue pergola which had a bit of a bashing from pidgeons' feet last year - the horizontal beams provide a perfect perching spot for flirting and generally hanging about. If you are considering painting any of your garden structures with outdoor paint, do consider the maintenance tasks - my wood work lasted only 2 seasons before looking shabby-chic distressed, but not in a good way. Now, it looks fabulous and crazy again, and the intense blue will set off the flowers of the climbing soft yellow Rosa banksii when it blooms in a few weeks time.

The pleasure of this early start to the year was enhanced many-fold because all my efforts have been accompanied by the intoxicating perfume of one small Daphne odora shrub, growing in a sheltered position behind the greenhouse. I have always felt that the Daphne is rather wasted, being tucked away in a not-very-visible corner. But this year itís come up trumps, scenting the whole garden, finding me wherever I am, and even inside the greenhouse. Glorious! If thereís one plant I wouldnít be without, itís Daphne odora.

Shall we talk about weeding? I know you donít want to, but hereís the thing. Most years, I canít weed until March, because my horrible claggy clay soil wonít allow it. Today I attacked the Evil Enemy, hairy bittercress (Cardamine hirsuta), before it has got around to flowering. New gardeners please pay attention! Hairy bittercress is an annual weed with fine lacy leaves, in fact it is rather attractive and lulls you into a false sense of security. So if you are busy and have time for just one task this week, I urgently advise an organised assault on the Evil One. This unassuming little plant with tiny white flowers produces thousands of seeds. Thatís why you must get it before the white flowers appear, and on no account add it to your compost.

There was once a time when I thought it was acceptable to use glyphosate weedkiller occasionally against the worse weed infestations - now I find myself thinking there is hardly any justification for doing so. It is useless against annual weeds like hairy bittercress which spread by seed (see above). Faced with a large area of weedy soil, I have found cardboard packaging to be really effective. Last year I created a new border, intending to have it planted and mulched by early summer. The very dry weather meant that I never got around to planting anything, so I covered the patch in a thiick layer of cardboard, weighted down with a few bricks. Nine months later, it has just about disintegrated and the soil below is as clean as a whistle - no grass, no bittercress, (OK, an occasional dandelion). Itís ready for planting and mulching any day soon.

With even the worse cases of perennial weeds like brambles, bindweed, couch and ground elder, I am reticent to recommend weedkiller. The environmental concerns of herbicides building up in the soil are paramount, but also, it doesnít really work. Most of the really tough weeds are difficult to treat, so that high doses and repeated applications are needed to have any permanent effect. The slightest bit of spray drift onto surrounding grass or plants will kill them. In practical terms there is no good substitute for digging them out (and yes, it may take a few attempts) - or long term mulching under a light-excluding material such as cardboard or landscape membrane. For infestations amongst established shrubs and plants, there may be no choice but to dig up and destroy everything so that the whole bed can be treated.

Penstemon 'Midnight' Salvia nemerosa 'Caradonna' Echinacea 'Tom Soup'

You could add an orange Crocosmia, but I never actually recommend it, as it can take over. All of these plants flower over a long period.

Plant profiles

Penstemon 'Midnight'

A semi-evergreen perennial, with tubular to bell-shaped deep purple-blue flowers flushed violet with a white throat produced throughout summer. This hard-working plant has the added appeal of dark purple stems to 70cm high, forming an upright clump.

Iris 'Superstition'

A bearded iris with sultry, purple-black flowers from April to May and greyish green, sword-like leaves. It looks stunning planted in drifts in a well-drained, sunny border, to harmonise with other blue and purple flowers, or to provide a dramatic accent among paler flowers.
Bearded Irises must be planted shallowly with the upper part of the rhizome showing on the surface of the soil. After planting, trim back the top third of the leaves to prevent wind-rock. In exposed areas stake with bamboo canes in early spring. Remove the stems after flowering from the base as this will concentrate the plant's energy into producing new rhizomes. Divide and replant rhizomes about every three years.

Iris chrysographes

This a serious Man Plant - dramatic, indigo-violet, almost black flowers appear in May and June above strap-like grey-green leaves. A clump-forming, beardless iris, related to the moisture-loving Siberian iris, makes a striking feature in a sunny, moist area of the garden, or beside water.

Salvia nemorosa 'Caradonna'

Many of the darkest flowered Salvias, like 'Amistad', are a little on the tender side, so I haven't recommended them as reliable garden plants. 'Caradonna' is a perennial cultivar with upright racemes of violet- purple flowers through the summer above narrow, rough, grey-green leaves. Not really a very dark flower, but it helps to lift the summer border to another level when mixed with the darker plants listed above.

Geranium phaeum

The species G. phaeum is an erect, clump-forming perennial with lobed leaves often with brownish markings, and flat, outward-facing delicate dusky purple flowers in late spring and early summer. A gentle plant for shaded areas. There are some good cultivars worth finding - 'Lily Lovell' has larger flowers, and 'Samobor' has lobed leaves bearing a striking deep brownish-purple zone, and slightly nodding maroon flowers.

Clematis 'Romantika' (clematis group 3)

How about a climber to complete the set. This has very deep purple flowers with contrasting pale yellow stamens. The blooms are produced from July to September and it looks particularly attractive when planted against a light background or growing through shrubs with light green foliage.
Prune back in early spring to a pair of strong buds about 20cm above ground level. Position in full sun or partial shade, in fertile, well-drained, neutral soil.