Some Like It Warm

You Don’t Need To Live In A Cool Climate To Grow Some Apple Or Stone Fruit Varieties. Here Are Our Low-chill Picks For Coastal, Warm Temperate, Subtropical And Some Tropical Zones

- Jennifer Stackhouse

For many years my mother grew an apple tree in her Sydney garden. She had grafted it as a student at horticulture college and kept it as a memento. It grew but never flowered or fruited, but not because of poor grafting techniques. It didn’t crop as, despite the odd frosty night in winter, the area wasn’t cold enough for apples to flower and fruit. Today, she could plant a low-chill apple variety such as ‘Anna’ and reap a crop each year.

Let me explain. Many of the most popular fruits that are produced on deciduous plants, such as apples, cherries and currants, need a cold winter climate to stimulate fruit production. The amount of cold is quite specific. Fruiting plants that need chilling accumulate hours of chilling beneath 7°C while they are dormant through winter before they break dormancy. The amount of chill hours (also called chill units) varies from species to species and variety to variety, from 100 to more than 1000. Lack of the correct amount of chilling means plants fail to flower properly and therefore do not form fruit.

Chilling hours act as a way to prevent deciduous plants flowering while there’s still cold weather around in cold climates. Controlling the start of flowering protects them from cold damage and also means that pollinators such as honeybees are more likely to be out and about when the flowers are in bloom and in need of pollination.