The Morello cherry (Prunus cerasus) is a fruit that is similar to the sweet cherry, but has a fruit body which is more sour, and so is useful primarily for culinary purposes.
The tree is slightly smaller than the sweet cherry, growing up to 27 feet tall, and has twiggy branches, whilst the crimson to black fruit is borne on shorter stalks and tends to be more darkly coloured. Cultivated sour cherries were selected from wild specimens of Prunus cerasus and P. acida from around the Caspian and Black Seas, and were known to the Greekss in 300 BC. They were also extremely popular with the Romans, who introduced them into Britain long before the 1st century AD.
The art of their cultivation was lost during the Dark Ages, although they were re-introduced to England in the 16th century by Henry VIII of France. They became a popular crop amongst Kentish growers, and by 1640 over two dozen named varieties were recorded. Massachusetts colonists planted the first sour cherry, Kentish Red, when they arrived in the Americas.
Before the Second World War there were more than fifty varieties of Morello and sour cherry in cultivation in England, however today few are grown commercially, and despite the continuation of named varieties such as Kentish Red, Amarelles, Griottes and Flemish, only the generic Morello is offered by most nurseries. This is a late flowering variety, thus misses more frosts than its sweet counterpart and is therefore a more reliable cropper. The Morello cherry ripens in mid to late summer, towards the end of August in Southern England. It is self fertile, and would be a good pollenizer for other varieties were it not so late flowering in the season.
Morello cherries require similar cultivation conditions to pears, that is, they prefer a rich, well drained moist soil, although they demand more nitrogen and water than sweet cherries. Trees will do badly if waterlogged, but have greater tolerance of poor drainage than sweet varieties. As with sweet cherries, Morellos are traditionally cultivated by budding onto strong growing rootstocks which produce trees too large for most gardens, although newer dwarfing rootstocks such as Colt and Gisella are now available. During spring flowers should be protected, and trees weeded, mulched and sprayed with seaweed solution. This is also the time when any required pruning should be carried out (nb. Prunus varieties should not be pruned during the dormant winter months). Morello's fruit on younger wood than sweet varieties, thus can be pruned harder. They are usually grown as standards, but can be fan trained, cropping well even on cold walls, or grown as low bushes.
Morellos suffer fewer pests and diseases than sweet varieties, although they are prone to heavy fruit losses from birds. In summer fruit should be protected with netting. When harvesting fruit this should be cut from the tree rather than risking damage by pulling the stalks. Morello cherries freeze well and retain their flavour superbly.
