Digitalis purpurea
Experimental feature

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Experimental feature

The famous garden designer, Russell Page, described many flower borders as “gaily coloured hay”. Those of us who are happy in our hayfields may wonder, deep down, whether we need to give them firmer shape and structure. One way is to increase the proportion of evergreen shrubs, telling ourselves that green is a colour and that it will all look so good in winter. Another way is to give more emphasis to vertical lines. My preferred way out of the hayfield is upwards, not greenwards. I realise how much the garden misses when the first verticals have finished flowering.

The talented gardener Norah Lindsay was once photographed in her Berkshire garden on a late June evening when the vertical lines of her plantings were at their most marked. I keep her design and its impact in my mind’s eye. Even in a black-and-white print, some of the crucial verticals are identifiable: the verbascums and the excellent Salvia turkestanica with lilac-purple spires of flower and a musty scent which was popularly known in Lindsay’s day as “hot housemaids”. Housemaids are now a vanishing species, but Salvia turkestanica retains its line and charm. It is at its best in mid-July when the foxgloves have run to seed. Track down its seeds from suppliers and sow them at once to give you plants for next year. They are basically biennials, at their best next year but needing early resown replacements for 2016. They set masses of good seed and are extremely easy to raise from one year to the next.

We have just had the month that is most easily filled with verticals. If you missed out on them, you can sow seeds of the best this weekend and expect them to show up next year. Foxgloves germinate so readily and take up so little space. They can be sown directly in lines in open ground and, if watered, will germinate thickly, ready for thinning and transplanting later in the year. Plain white foxgloves show up best when set at intervals around a garden as if they have casually seeded themselves. Apricot-flowered foxgloves are pretty too and selected seed is still available of an Apricot strain from Thompson and Morgan or Suttons Seeds. Cut down the main stems as soon as they have flowered as foxgloves will rapidly set fresh seed and many of the seedlings will not come true to the parent, especially if cross-pollinating insects have been busy during the flowering weeks. When foxgloves are cut back to one basal rosette of leaves in July they take up little space in any border but can still survive strong competition from neighbouring plants. Ifthe plants are too dry, the leaves go a pale shade but still live on. When in flower they give a planting the necessary vertical line – the extra dimension above its head.

Delphinium Larkspur

So do lupins and, again, they can be sown now and still have good prospects for next year. Like foxgloves, they too must be deadheaded at once, and in their case, the deadheading stops them wasting their limited energy. If they do not set seed, they last better the following year. They too die back usefully but they are less tolerant of close competition from surrounding “hay”. Again, a few plants dotted round at intervals make more of a vertical impact on a garden than one traditional clump, so much harder to hide after flowering.

Like The Prince of Wales at Highgrove, I love delphiniums, not least for their strong vertical line. Unlike him, I grow my best ones now from seed, the remarkable Centurion Lilac Blue Bicolour variety, a strong hybrid which Thompson & Morgan’s seedlist has brought to gardeners’ notice. They consider it to be every bit as good as most of the expensive named varieties that are grown only from cuttings. I entirely agree with them.

Verbascum Helen Johnson

Centurion Blue is a lovely lilac-blue with a white central “bee” to each flower and so long as they are promptly deadheaded they last well from one year to the next. They too can be sown this weekend. They are winners and are much cheaper than individual pot-grown named beauties at £7.50 each.

The most spectacular verticals both in Lindsay’s old photograph and in modern reality are tall Verbascums. There are two especially good options. One is Verbascum olympicum, which makes a big grey-leaved rosette and then sends up branching stems of yellow flowers, like tall candelabra, to a height of 5ft or so. The other is Verbascum bombyciferum Arctic Summer, which reaches the same height but has furrier stems and more of a grey-white presence. They too should be sown right now, with seeds available from Chiltern Seeds and many others, if not immediately visible on the racks of your local centre.

Lupinus Masterpiece

In the gravel walkabout garden at Petworth House that I mentioned last week, these verbascums are a major presence. They lift the eye above surrounding cistuses and so forth and give an extra dimension to the design.

So far, so easy, but the problem is how to maintain the vertical line from now until October. The essential asset until later August is the hollyhock. In a formal border, in the back row, hollyhocks’ habit of losing their lower leaves to rust disease is not visible. All that shows is the tall flower spike, the king of verticals so long as it is staked in good time. I am less fond of the basic rose-red forms and much prefer whites, yellows and dark reds.

Digitalis ferruginea (or rusty foxglove) with Buphthalmum salicifolium Sunwheel

A limited combination of single-flowered whites and the dark near-black ones classed as “blackcurrant” is most impressive. In smaller beds I prefer the excellent Alcea rugosa, with smaller pale yellow flowers that are not so top heavy, even on stems up to 6ft high. As a recent introduction from the wild, it is not a hollyhock Lindsay ever knew.

I have not yet cracked vertical September and October. There are tall border plants galore, but only the blue monkshoods or aconitums have a vertical line and then only from fairly short spikes of flower. The not-so-hot pokers, or forms of Kniphofia, are mostly over and there is nothing really vertical about a mixture of Michaelmas daisies and yellow-flowered helianthus. At first, the spectacular upright lines are given by yuccas, but they do not last for ever in flower and the pointed leaves are not to everyone’s taste.

Norah Lindsay and husband Harry at their home in Oxfordshire, 1905

By mid-September the last of my thumpingly unfashionable gladioli are going over, pointed and tall though their flower spikes have been. As a vertical accent among too many hardy geraniums and fading phloxes, well-staked gladioli have definite class. They are not there, however, when the dahlias and asters dominate.

Perhaps the year should go gracefully to its end without the strong lines of early June and July. I miss them, nonetheless, and will continue to watch for candidates. Meanwhile, I am hunting out self-sown seedlings off foxgloves, Salvia turkestanica and verbascums so as to lift them, transplant them and grow them on to be the skyscrapers of 2015.

Photographs: Gap Gardens; Country Life

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