Since midsummer I have been trimming, clipping and deadheading, crucial work in keeping a garden looking good. In this heavenly year for British gardens, there has been plenty to cut back and tidy. Most plants have grown more profusely than ever in the cooler weather. One difference between a garden and a conventional work of art is that gardeners have to keep at it, whereas sculptors can let a final version go. A garden is always a work in progress.
How does a big border progress when it is not in my care or under my supervision? Seven years ago I described the huge double border at the Sir Harold Hillier Gardens near Ampfield in Hampshire, one of the biggest and boldest to have been laid out recently in a space open to the public. On either side of a long central walkway of mown grass two borders run each to a depth of about 20 metres and a length of 250 metres, broken by a central meeting point. The soils vary, as often in a garden.
One of the borders is slightly shaded and the other is in full sun. The backdrop to both is the canopy of green trees and tall shrubs in the surrounding arboretum. Both borders are fronted with paving, one slab wide, to simplify edging and access. They are a major statement on a major axis of this public garden. Planted in 2012, they would have been a disaster if they had gone wrong. They are quite the opposite, a fascinating example to new border planters, whatever the scale of their project.
The two borders took over from others which had lost their impact. In 1964, the great Sir Harold Hillier decided to plant a centenary border to mark the 100th year of Hillier Nurseries, founded by his grandfather and made internationally famous for its range of plants. The border’s surrounding trees and shrubs eventually became a tangle and its planting became dull. In 1977, the whole of the Hillier garden and arboretum passed to Hampshire county council, who have shown admirable commitment ever since. The replanted Centenary Borders are an example.
When I last saw them they were already extremely impressive: have furlough and the passage of time taken the edge off them? In the lockdowns, Fran Clifton, their supervisor, had to oversee the entire garden while the posse of volunteer helpers was much reduced. Some annual cottonweed still needs to be pulled out, but the double border has sailed through the interruption. It is in fine form and is full of ideas for us all.
Among his many distinctions Hillier was a keen fan of cricket. In his honour the designers of the new borders worked with a basic unit of 22 yards, the length of a cricket pitch, in order to unify their plan. Within each section they planted in blocks, not narrow strips, and repeated some of the plantings in order to draw the eye down the entire border’s length. I use the same trick. If seasonal performers are spaced out, a spectator’s eye will jump over others not in flower and move on from one patch of colour to the next down a border’s full length. The two Hillier borders do not mirror one another, but some of their groups are repeated from one side to the other. Last year I admired this effect, a more pronounced one, in the superb long borders at Newby Hall in Yorkshire.
I approve of the Hillier borders’ use of flowering shrubs. They give form and height to a surrounding mass of herbaceous stems and leaves. Clifton rates the deutzia family especially highly for a border, and I agree. Deutzia Strawberry Fields and Iris Alford are two of her favourites, to which I would add the pale pink and white Pride of Rochester, a lovely variety. In later July, the excellent white Deutzia setchuenensis corymbiflora prolongs the season, but is not always hardy in colder gardens: unlike the others it does not need to be pruned after flowering. When it is going over, evergreen Abelia grandiflora maintains the show.
In all but the coldest gardens I really rate this profuse pink-flowered, glossy-leaved shrub for a mixed border. It is about 5ft high and wide. I never prune mine. I do nothing to it at all. In return it flowers for months, looking great with dahlias. In the Hillier border the dahlias are never lifted. Clifton advises cutting their stems down to soil level when the frost blackens them and then putting a mulch of leaf mould or rotted compost on top of the soil to a depth of at least nine inches.
These mini mounds, held in place with wire netting, bring dahlias through weeks as cold as those last winter. They save the bother of lifting the tubers yearly and storing them in a shed, my task in mid November. The mulch, however, has to be deep.
Height is essential in such a long stretch of planting and here, the Hillier borders hit the target. Tall metal frames of iron, like elongated tree-guards, were commissioned from a local craftsman and then planted with a vigorous late-flowering clematis in each one’s centre. The clematises should be fed from spring onwards and will then race up inside the iron cage and conceal it by mid summer. This weekend they are flowering freely, especially those from the viticella group in the family, Minuet and Kaiu being two of the Hillier borders’ stars. If you want to add an extra layer of flowery height to a border, invest in ironwork made locally and follow this clematis trick.
To my delight I found border plants, new to me, to consider for use at home. Phloxes have had a superb year in this cool summer, but we all need to hunt around for the ever-better varieties on the market. They flower longer and resist mildew. In Hampshire I noted the brilliant red Phlox Kirchenfurst (offered by at least 10 suppliers in the RHS Plant Finder) and Phlox arendsii Miss Jill, white with a red central dot (listed by at least seven suppliers). In August, phloxes are improving winners, better and better the further north your garden lies.
Two surprises caught me out. Both are extremely easy to raise from seed (chilternseeds.co.uk is a source of both). Alcea officinalis grows to the useful height of about 5ft and is a wild hollyhock, grey-white in flower and most obliging. I wrote recently about its fellow hollyhocks but never expected to see it looking so good in a major British border.
Also on the shaded side, the so-called Golden Lace, Patrinia scabiosifolia, is an eye catcher, puzzling my unsuspecting eye. About 3ft high, it has masses of small acid yellow flowers which stand out in a long vista. In semi shade, it is a simple plant we have been neglecting.
Three weeks ago, I criticised the expensive installation by city councils of that mound at Marble Arch and the meadow in boxes in central Oxford. One cost £6m, the FT discovered, the other at least £120,000. Hampshire county council has shown far wiser patronage over the past 40 years. It has supported one of the outstanding collections of plants in Britain and delighted thousands of visitors with gardening at its best.