Climatic regions suitable for chestnuts
At Chestnut Brae we often get asked if Sweet Chestnut trees will grow in Perth. Well the answer is yes, they will grow in Perth region, but they are highly unlikely to bear fruit. I have gathered together some information on the growing conditions that chestnuts require.
The chestnut (Castanea sativa mill.) is a medium-sized tree, growing 20–35 m tall and 6 m wide. The tree has thick, oblong-lanceolate leaves and prefers mild summers and cool winters. Chestnut trees originated from Europe and Asia Minor and have a long-standing role in the human diet in Asian and European countries. In Europe, during medieval times, one chestnut tree was said to provide one person with a lifetime of sustenance and one tree was planted for every child born in towns under siege.
The monoecious flowers bloom in November and December and nuts are harvested between March and May. Catkins are bi-sexual with pistillate (female) flowers located at the base of the catkin. The remainder of the catkin is staminate (male) flowers. Pollination (wind) often occurs before pistillate flower receptivity, hence multiple cultivars are recommended. It is possible for each pistillate flower to develop into 1–3 nuts, with the cultivar influencing the quantity, therefore the size of nuts, produced in each pistillate flower. The cotyledon, or edible portion of the chestnut, is encased in the pellicle, a hard shell, protected within an involucre, or spiny bur. (https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0011/586487/chestnut-industry-expansion.pdf)
Chestnuts grow best in areas with cool to cold winters, warm to hot summers, and moderate to high rainfall, preferably with a substantial summer component. Maximum temperatures of 25°C to 30°C are needed to ripen the nuts.
In Australia chestnuts are grown mostly where rainfall is around 750 to 1500 millimetres/year. Such areas usually have some summer rainfall, but irrigation can be used as a supplement (see Irrigation). Rainfalls reported for other countries vary from 800 millimetres/year to 2000 millimetres/year. (Gomes-Laranjo et al. 2012) but may go as low as 500 millimetres/year.
In Australia, chestnut-growing areas are generally 300 to 800 metres above sea level but can be up to 1000 metres.
Some challenges in relation to temperature include:
- Higher temperatures will tend to push nut growing locations to the higher end of the 300 to 1000m current range;
- Higher temperatures may result in suppressing yield.
Deciduous trees need a period of cool temperatures to break dormancy and start spring growth. Inadequate chilling causes poor cropping. There are a number of ways to measure chill units, one of which is the specific number of cumulative hours of temperatures lower than 7.2 °C. For chestnuts the chilling requirement is estimated to be 300 to 400 hours (Stanford University n.d.); this is the equivalent of 2 to 3 weeks of chilling if the exposure to temperatures below 7.2 °C is continuous.
Chestnuts prefer deep well-drained, fertile soils. Chestnuts do not respond well to liming or poor drainage. It is recommended that chestnut plantings are established on slopes to improve the drainage. Preferable sites selected for orchard establishment will have soils that are well drained, highly fertile, have low salinity levels and low clay content. Unfortunately, such descriptions cannot commonly be applied to Australian soils.
So, in a nutshell, if you live in Perth you can enjoy the shade of your beautiful chestnut tree, but if you would like to enjoy fresh chestnuts, come on down to Nannup in April or May and bring your family and you can create a wonderful annual family tradition of picking your own chestnuts at Chestnut Brae.