Fruit Tree Chill Hours & Pollination Planner
Pick a fruit tree and enter your winter chill hours to see whether it suits your climate and how many trees you need for pollination.
Two things decide whether a fruit tree will actually fruit for you, and neither shows up on the label on the day you buy it. One is winter chill: stone and pome fruits need a certain number of cold hours to flower properly. The other is pollination: some trees fruit alone, others need a second tree. This planner checks both for 16 common fruit trees.
Fruit Tree Chill Hours & Pollination Planner
Chill hours are hours below 7°C over winter. The ranges are typical across varieties of each fruit, from low-chill to high-chill. Variety ratings vary, so confirm the chill rating and pollination partners of the variety with your nursery before you buy.
Chill hours its varieties need: —
Fit for your chill hours: —
Choosing a variety: —
Pollination: —
Trees to plant: —
Small-space option: —
Full guide, more detail, and a printable version at https://hollyshomestead.com.au/tools/fruit-tree-chill-hours-pollination-planner.html
How It’s Worked Out
Each fruit has a range of chill hours across its varieties. Low-chill varieties flower and fruit in mild winters, and high-chill ones need a cold one. If your winter chill is above the top of the range, any variety will do. If it is inside the range, you need a variety rated at or below your hours, and a margin of 10 to 20 per cent is sensible because chill varies from year to year. If it is below the bottom of the range, the tree is unlikely to flower properly and fruit.
Pollination is a separate question. Self-fertile trees set fruit alone. Others need pollen from a different variety of the same fruit that flowers at the same time, and kiwifruit needs a male and a female vine. A neighbour’s tree within about 30 metres can sometimes do the job, and a single tree grafted with two varieties covers a small garden. Bees do the carrying, so flowers nearby and no spraying while the tree is in bloom both help.
Finding Your Chill Hours
Chill hours are not on most weather reports. The simplest sources are a local nursery or horticulture advisor, a neighbour who grows the fruit, or hourly temperature records from the nearest weather station, counting hours at or below 7°C from May to August. As a rough picture, frost-free tropical and subtropical coasts get very little, mild coastal areas get a few hundred, and cool highland and inland districts get several hundred to over a thousand. Because the figure moves from winter to winter, choose a variety that is comfortable at your number, not just marginal.