When to pick English walnuts depends on a few different factors, but mainly their appearance. How they look may differ depending on the amount of water they receive throughout the growing season, making it more difficult to determine when they are mature. If you know the time frame when English walnuts usually mature, it gives you a base to start with; from there, look at a few different indicators as general guidelines for when to pick these nuts.
English walnuts, when hydrated, start to burst open their hulls when mature. When the nuts are ready, you will notice all the nuts on the tree have opened their hulls. If the walnuts haven't fallen to the ground yet, you can shake the tree limbs to dislodge the nuts for harvesting.
Lack of Water
English walnuts still mature even when not properly hydrated, but their hulls do not usually burst open. This makes it more difficult to identify when they are ready to pick. Wait until the tissue between the kernel and inner lining becomes brown. When mature, the hull usually becomes loose. Pick a few nuts and inspect the kernel for these signs to determine if the nuts on the tree are ready for picking.
English walnuts are usually ready to pick in late August through September. This type of walnut may continue to mature throughout October and as late as November. Start checking the nuts to see if the inner tissue has changed colour or the hull is loose around late August.
Warnings & Suggestions
Picking walnuts after they have had too much time to mature results in dark-coloured kernels and mould, which spoils the nut. After picking, hull the walnuts and allow them to air dry for two weeks before storing or eating. Store shelled walnuts in a refrigerator or freezer for up to a year. Walnuts in the shell last for several months when kept in a cool, dry place.