As with all orchard trees, pruning is vital, both to maintain the health of the trees and to keep harvesting practical and cost-effective. Pruning should be undertaken from July to January to remove any crossing branches and low growth to maintain a practical clearance for harvesting, but also to allow for adequate light penetration, both for the fruit and the grassy sward underneath the canopy.
Harvesting fruit is determined by your orchard design, species choice and the final product to be marketed. There are two main harvesting periods, detailed below:
- When harvesting nuts as Wet, this means that the fruit has not had a chance to dry within its shell. Harvesting should be undertaken before the shells harden during the summer months while the husk is still green; it is useful to check with a skewer or knife before starting.
- When harvesting nuts as Dry: This means that the fruit has begun to dry within its shell while still on the tree or ground. Harvesting should be completed in a timely manner. As soon as the fruits fall from the tree or are shaken, you have 24-48 hours to harvest, remove the husk, and clean them, or there is a risk of moisture contamination that will taint the nut kernels. This can lead to a bitter taste in the nut which you want to avoid at all costs.
- Traditional harvesting machinery is a labour-intensive method using a ‘Nut Roller’. Mechanised methods have replaced this method in commercial orchards as they are more cost-effective; tractor-mounted vacuums and self-propelled harvesters are used.
Once harvested and cleaned, the nuts need to be dried and drained to remove most of the moisture content to prevent rotting – generally, around 10-12% moisture content is ideal. A standard commercial unit can expect to dry 1-2 tonnes in 72 hours, depending on the moisture content of the nuts. This is a costly process; Burmington Farm uses a unit that runs off bottled propane gas, so an effective drying method and plan is key. Once dried, the nuts will keep in a suitable storage area for up to a year before being processed and distributed. Depending on the final product required, cracking and de-shelling of the fruit is necessary. Without investing in specialised machinery, this can be a laborious task. Once de-shelled, Walnuts will yield between 4 and 8 grams of kernel, roughly 25-50% of the original weight.