Avoiding damage to fruit blossom
The earliest-flowering fruit are usually the apricots, closely followed by peaches and nectarines. Then come plums, red and white currants, blackcurrants, gooseberries, pears and, a fortnight or so later, apples, soon followed by the early summer strawberries.
In temperate climates all these fruits may be damaged by frost should it occur when the blossoms are open. One obvious way of avoiding frost damage to fruit blossom is to avoid growing the earlier fruit at all, concentrating instead on such kinds as raspberries, blackberries, loganberries and other hybrids, and perpetual-fruiting (remontant) strawberries, which flower much later. If you did this, however, you would be greatly limiting the range of your fruit growing.
As the spring advances, the odds against a hard night frost increase, so that in cold gardens and exposed districts it is worth choosing the later-flowering varieties of plums, pears and apples.
The following plums, arranged in order of blossoming time, all flower about a month later than the earliest varieties: Early Transparent Gage, Far-leigh Damson, Kirke’s, Giant Prune, Early Greengage, Teme Cross, Pond’s Seedling and Marjorie’s Seedling.
Late-flowering pears, not reaching full-flower in areas such as the South of England until about the end of mid-spring, include Dr. Jules Guyot, Williams’ Bon Chretien, Improved Fertility, Pitmaston Duchess Catillac, Beurre Superfin Clapp’s Favourite, Glou Mor-ceau, Bristol Cross, Winter Nelis, Doyenne du Cornice and Gorham.
Apples blossoming some three weeks after even these late pears are New Bess Pool, Edward VII °Court Pendu Plat (once known as ‘The Wise Apple’ because it often does not flower until the beginning of early summer), and, some five days later still °Crawley Beauty, fortunately self-fertile.
No varieties of currants or gooseberries are really frost-resistant. They flower early, so that frosts not affecting many tree fruits may wreak havoc among these bush fruits. All cane fruits flower late and usually crop well despite spring frosts.
For frost to cause damage, the flower bud, flower or young fruit must be subject to a low enough temperature for a long enough time. The amount of damage done depends on the stage of growth reached. Generally speaking, the young fruitlet stage is most susceptible and the unopened flower stage the most resistant, with the open blossom stage in between, though there are exceptions to this, such as the cooking apple variety Bromley’s Seedling, which is most susceptible to frost at the unopened flower stage.
There are also, in fact, quite marked differences in frost resistance between different varieties. So another approach to the frost problem is to grow varieties which show more resistance to frost than their relatives.
Among plums, Czar, Warwickshire Drooper, Marjorie’s Seedling and Giant Prune have a reputation for frost resistance, and among pears only Con-ference and°Fertility show signs of this. Overall, pears are more resistant to frost damage than are apples, but they are rather more prone to damage at the fruitlet stage.
Apple varieties said to be less susceptible to frost than others include Worcester Pearmain, James Grieve, Ellison’s Orange, Epicure, Ontario and Wagener.
Peaches, nectarines and apricots are at risk at all stages. Strawberries are also extremely susceptible to frost, because their flowers are so close to the ground, but Huxley is the least susceptible variety.