Up against the wall

The dry spring is particularly dry for plants on or against walls. I spent part of Easter checking my wall-plants’ condition and marking their progress out of 10. They might as well have been trying to translate ancient Greek. They scored very low marks indeed. How can they be improved?

It would help if I still enjoyed going up ladders. The bigger climbing roses are tangled in disorder round the highest wires that I fixed into the house walls. One has broken all bounds and a length of the guttering and has started to head for the chimneys. As it is a rose called Mrs Honey Dyson and is not even in the Plantfinder I dare not simply reduce it by two-thirds. It may be one of the few specimens left in cultivation since I was given it in 1975. In late June I will forgive Honey everything as she covers herself in peach-white flowers, turning the roof into a carpet of roses. She ought to be brought back onto general release as she is such a magnificent rambler.

Elsewhere the honeysuckles have been hit already by aphids. The warm spring brought the bugs out in force, so I have just sprayed the leaves with Provado to see them off. From the honeysuckles some of the aphids then transferred to the flowers of the excellent deep red Tulip Couleur Cardinal. If the tulips are looking stressed this week it is worth checking for aphids and spraying them too. It is amazing how many of these bugs proliferate on a single stem.

Now that hosing is forbidden I have been watering and feeding all clematis from individual cans. They respond so well to early feeding, maintained throughout the growing season at fortnightly intervals. I use diluted Phostrogen and notice how dry the ground around these climbers has become. My old favourites remain the blue-purple The President, white Henryi and the excellent sky-blue Perle d’Azur with a darker centre. Against walls they did not have the benefit of the early morning dew in March’s dry spell, so they need attention now. The spring flowerers have been magnificent nonetheless. The white-flowered Clematis armandii has leathery big leaves that can look untidy but its flowers are beautifully almond-scented and have been prolific after a mild winter. It is such a popular clematis for the low walls that separate town gardens but it is actually a climber with almost as much vigour as Mrs Honey Dyson. It belongs on the high wall of a house where it will show remarkable strength. I have admired it up on other people’s chimneys while it flowers magnificently down the entire roof.

Suppose I had to start again and choose wall plants for each wall of a house. Much would depend on the shelter of the wall and its height but in mild London or Cornish conditions it would be hard to resist mimosa facing south or west. In most of rural Britain it would be dead by mid-December. White-flowered Solanum jasminoides album is marginally more reliable because it will usually sprout from the root after a winter as hard as 2010-11. Old plants have begun to scramble back again after their decimation and I look forward to the mass of late summer flowers, sometimes lasting into a modern December. It is a magnificent choice for a sunny wall in London, whereas sky-blue plumbago is an ignorant one, with little chance of lasting two winters.

I assume you would plant a wisteria if you really had enough south or west facing room for one. One of the quickest to flower is floribunda Issai but the flowers lack the magnificence of a deeper violet variety. Myself I have had years of pleasure from the yellow-flowered Clematis Bill MacKenzie when facing south. No winter kills it and as its dead growth should be cut right down to only two foot or so in spring it is never a bother at too great a height. It is usually recommended for shadier sites but in fact it is even better in hot sun.

West walls are excellent for climbing roses but I am glad of advice from the great breeder David Austin whose varieties now dominate so many garden centres. He and his nurserymen point out that many of the recent David Austin roses are especially good if trained against walls. Facing west I would recommend them, draped with a late summer clematis, probably one of the viticellas that flower so freely and need to be cut back each spring too. They are usefully out of sight when the roses first flower. If there was room on the wall I would include a white-flowering jasmine even though the biggest flowers are on the lovely far-eastern varieties, which are not hardy in Britain. Jasminum officinale Grandiflorum is still the best white but it is a vigorous climber, well able to reach 20ft. If there is less height I would use a shrubby Viburnum burkwoodii for spring scent instead. These easy white-flowered shrubs take very well to a tightly pruned life against a west or east wall but are often forgotten for the purpose.

Facing east, there would have to be honeysuckles, especially the spectacular Lonicera brownii Dropmore Scarlet. It has no scent but the tubular flowers are a superb scarlet from July onwards and are unmissable. Among roses the dark red Etoile de Hollande is excellent facing east or even north, although it grows to quite a height. So is the beautiful pink Mme Gregoire Staechlin, another tall grower. Many of the best clematis will thrive here too, especially the later-flowering ones, which can be cut near to the ground early in the year and thus avoid damage from cold east wind. On lower walls the spring-flowering “japonicas”, listed as chaenomeles, are the neat answer. They can be pruned hard after flowering and kept as well-spaced specimens. They are near their best this weekend and tough enough for any British winter.

North walls are considered to be the problematic ones but the aspect is less significant than the access to light. In dark shade few plants will make any impact, but if a north sunless wall is open to air and light there are actually many options. My favourites are the pyracanthas, which too many gardeners still ignore. In late autumn the berries are so spectacular and nowadays the recent Saphyr series has much greater resistance to the deadly fire-blight. The beauty of a pyracantha is that it can be clipped into any pattern you choose and can even be shaped into an evergreen edging round windows. Several roses will flower well enough, especially the vigorous climbing form of the small-flowered pink Cécile Brunner. Again, white-flowered Viburnum burkwoodii will distinguish itself so long as there is light available. One of the least known options is the scentless but large-flowered yellow honeysuckle Lonicera tragophylla, a lovely variety that prefers a shaded aspect. In case of doubt, always head for the vigorous scented Lonicera japonica Halliana, which will cover anything, including a dustbin. It is the one whose flowers change from cream to biscuit-yellow but are exceptionally sweet-scented. Its saving grace is often missed. It can be cut back in winter to a stem no more than a foot high and it will then race away all over again but not become a total menace.

Having gone round the four walls of a house I could go round again with so many other options. Looking at my failing myrtles I begin to think that mine too need a fresh start.

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