You can tell your walnuts ready to harvest by one clear sign. The green outer hull starts to crack and pull away from the hard shell inside. This split tells you the nut has finished growing on the branch. You may also see the hull turn from bright green to a dull yellow-green or brown color as it loosens up. Most trees drop their ripe nuts to the ground on their own once the hull opens.
I use a simple thumb test on nuts still hanging on the tree to check if they are ripe enough. Press your thumb into the green hull and push down with firm pressure. If the hull dents and stays dented like a ripe peach, that nut is ready to come off the branch. If the hull springs back and feels rock hard, leave it alone for another week or two. I check my trees every few days starting in early September so I never miss the right window.
Your walnut harvest timing lines up with a window from September through October for most varieties. Walnuts ripen from the inside out, with the kernel reaching full size before the hull ever starts to split. If you pull nuts too early, the kernels inside will be small, pale, and shriveled instead of plump and golden. Waiting for that hull split means your kernel has had time to fill with oils and reach peak flavor.
Collect fallen nuts from the ground every single day during your harvest window. Walnuts that sit on damp soil for more than 48 hours can start growing mold on the shell and inside the kernel. You also need to strip the hull off each nut within 24 hours of picking it up. Hulls left on the shell leak tannins that stain the shell dark brown and can give the kernel a bitter off-taste. I wear rubber gloves for this job because walnut hull juice stains your hands black for days.
After you hull your nuts, spread them out in a single layer on wire racks or old window screens to dry. OSU Extension says the best drying temperature sits between 95 to 105°F (35 to 41°C) with good airflow around each nut. You can dry them in a warm shed, garage, or covered porch as long as air moves across the nuts and keeps moisture from building up. Drying takes 2 to 3 weeks depending on your local humidity levels.
Test your nut for dryness by cracking one open and snapping a piece of the kernel in half. A dry kernel snaps clean with a crisp sound and shows no bend or flex. A kernel that bends or feels rubbery still has too much moisture inside and needs more time on the rack. USU Extension notes that dried walnuts store 3 to 6 months at room temperature in an airtight jar. You can also freeze them for up to a full year.
Knowing when to pick walnuts comes down to watching your hulls, testing with your thumb, and collecting fallen nuts every day. Start checking your tree in early September and keep at it through October. Get those hulls off fast, dry your nuts with good airflow, and store them right. You will end up with a pantry full of fresh walnuts that taste far better than anything you can buy in a store.
Read the full article: Growing Walnuts: 7 Key Steps
