For gardens, April has been a cruel month

Gardens have been having a very testing spring. Garden watchers may have missed the difficulty of it. Apart from a sudden snowfall, April was almost entirely dry. Worse still, it combined drought with a cold wind and very cold nights. Plants hate this combination. We have had three dry springs in a row in Britain, but this one caps the other two, a downside in a changing climate. Last year’s dry start lasted almost throughout May, but had none of the chill that has taken the joy out of gardening during many recent weekends.

The dry cold has also done serious damage. In France, as in southern England, vineyards have been crippled by sharp early frost. In Chekhov’s famous but enigmatic short story “The Black Monk”, owners of a big fruit farm in Russia hurry to light fires at night to keep off a cruel spring frost that will ruin the trees’ blossom. The episode is integral to the plot, but it strikes modern readers, safe in a city, as a quaint echo of a peasant past. It is no such thing. In claret country, desperate owners of vineyards have resorted to night-time fires as a defence against ruin of their vines’ flowers. Fires at night are still their best hope of countering nature’s cruelty. Despite them, frost, as in Chekhov’s story, has wrecked an entire year’s projected grape crop. We will have to look beyond France for much of this year’s fine wine.

Even in London, magnolias, camellias and wisterias have suffered. Very cold nights turn the flowers on many magnolias and camellias a dirty brown. If a wisteria’s buds are too far advanced, a sharp April frost will wipe out its flowers altogether. In colder parts of the country the buds were not fully formed, but in warmer towns owners of wisterias may be in for a disappointing May.

I have ended up with Concha and AT Johnson, two good blues that are probably safe in most British years in a sheltered yard

Lacking acid soil, I do not have to worry about the safety of camellias or rhododendrons in bud. I rely on two other families for a May display: ceanothus and viburnum. The viburnums are still fine, essential choices in any garden. Some of the finest are Viburnum carlesii and its named varieties, Aurora and Diana being justly favoured. They have exquisitely scented heads of white flower, sometimes tinged with pink, and are impervious to frosty nights. Cold evenings merely accentuate the delicious scent of their flowers.

They grow rather slowly to heights of 5ft or more but can be kept to a tighter shape by pruning as soon as their flowers turn brown in May. They fit, therefore, into a front garden, carlesii and its varieties being the best among several fine contenders. Viburnum burkwoodii will even grow well against a north wall if it has light and air.

The main downside to viburnums is that those in the trade have been grafted on to a coarse rootstock to hurry along their handsome top growth. Usually this root stock throws up stems beside the plant’s main core, but they are readily identified by their rougher leaves, shape and texture. Check for them this weekend and cut them right down to ground level to stop them diverting the plant’s strength from its desirable main stem.

As many of you have found, ceanothus tell a different story. They are well known to Californian readers as California lilacs, blue blossom and so forth, but Britain is not Santa Barbara. They give us vivid masses of blue flower, often deep in tone, and grow gratifyingly fast, just what owners of short-term gardens need. They are the ideal short-cut to a look of maturity.

Unfortunately, most of the best are susceptible to frost and have hated this spring. A wise response is to break the branches on browned evergreen bushes and see if the wood is still green inside. If it is, cut the frosted side-shoots back to this old wood. At worst, on an evergreen variety, try cutting the old wood too down to the shrub’s base. It might shoot again near ground level, though the odds are against it.

I have been looking for ceanothus anyway for a new planting. In my mind’s eye I envisage three evergreen bushes, clipped to about 6ft in height and covered with blue tufts of flower in May. They will be followed by single yellow roses on the excellent shrub rose Golden Wings. I like blue and yellow but the frost has done its best to frustrate the plan: good ceanothus are in short supply after this cold spring.

Among evergreen ceanothus, the hardiest are the tried and tested ones, though not entirely infallible. Look for Ceanothus Delight, which has long bunches of blue flowers in spring, and Ceanothus x veitchianus, which has deep blue flowers in late May. Delight won an Award of Garden Merit from the RHS in 1926, long before anyone talked of global warming. Next best for survival include AT Johnson, which flowers freely in spring and summer, and Southmead, which is usefully compact, small-leaved and bright blue in late May and June. Puget Sound and Italian Skies are lovely against a sunny wall but they will not survive a severe winter, though Londoners may be luckier with them.

Failing to find a good plant of Southmead, I have ended up with Concha and AT Johnson, two good blues that are probably safe in most British years in a sheltered yard, even away from a wall. Among non-evergreen varieties, the choice is a bit wider as they lose their leaves anyway and can be pruned back now to a low point on the bush if it is still showing green life under its bark: do not muddle them with cistus bushes, which hate to be cut far back into old wood.

Gloire de Versailles is still the winner here, a lovely pale blue feature in August and September in a mixed border, but Henri Desfosse runs it close, being more upright with flowers of a strikingly deep indigo. The top stems of each have died in the open in our Oxford garden but both can be pruned this weekend to green stems lower down. They then grow back very quickly and are excellent fillers for any new flower bed that is looking bare in its early years.

Lower down, I rate ceanothus as a flowery ground cover, suppressing weeds. The lower-growing varieties are among the hardiest, the toughest being Blue Mound, a wide-spreading shrub to a height of up to 3ft. A mass of it is excellent when spaced at intervals to cover bare ground down a bank, beside a driveway or on the sunny edge of a shrubbery. It also fares well in Mediterranean climates, making it a good choice for open, weed-prone space in a holiday garden. A darker-flowered alternative, Emily Brown, is even more impressive in flower and well worth buying.

I have never lit a night fire to protect a ceanothus. They come and go in our lives, but are always forgiven and replaced.

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