[Sandra]

How do I know when the nuts on our walnut tree are ready to harvest? It's about three years since we planted the tree and this is the first year it has fruited (if that's the correct thing to say about a nut tree). There are only about ten nuts, so every one will be precious...just hope I haven't missed the moment!

[David Bracey]

When ripe the nuts will start to fall.  Leaves also start to fall at the same time. This is probably too late however its the best I can do. 

Walnuts are grown professionally in the Iszere and I think parts of the Dordogne regions of France where autumns are dry.  Tobacco is also grown in the same areas.  Rain in the autumn causes the nuts (kernels) to turn brown , with a disease, and they loose some of their value.  Manufacturers demand a "white" nut.

[John J]

Here in Cyprus Walnuts are mostly grown at higher altitudes (500-1400m) especially in stream valleys as they prefer a more fertile, moister soil. They tend to ripen around Sep/Oct under these conditions. They are also picked when green and immature for making into a syrupy sweet, the whole thing being boiled in water, that is changed daily, for several days as the start of the process, a lengthy, messy business.

[Alisdair]

That's true in the southern Peloponnese, too, John, where the best nuts come from several hundred metres up, and I suspect is pretty general in the extreme south of Europe, and in the eastern Mediterranean.
The commercial plantations that David mentions in France are at lower altitudes, and extend into the south of the Charente. There are several in the area of our house in SW France. Our own nuts there are never ripe at the time of our usual visit in September, so we sometimes pick a couple of kilos green, bringing them back to UK to pickle - but invariably, faced with all that tedious messy process mentioned by John, we leave them in an outhouse until we have to throw them out!
As David says, the nuts do fall when ripe, but are ripe still on the tree when the green covering starts to split and blacken.

[JTh]

In Halkidiki the walnuts are gathered in October (mostly growing somewhat higher up), but I believe they wait until the walnuts start to drop on the ground. I have read that you should not pick nuts from the trees, beacuse you risk damaging the branches and reduce future nut production, the branches are very fragile. It's no use picking the nuts before the husks start to soften.

[Alisdair]

I suspect that the warning about damaging branches by picking from the tree applies to commercial picking, or to attempts to knock the nuts off. We have found no risk of damage when we've been hand-picking green (nor indeed when we prune the tree, which we do fairly drastically in early autumn - not the best time).

[David Bracey]

There`s a very easy receipe for pickling green walnuts in a brine mixture.  No messy at all, but I`m not going there!!

[John]

For many years we have had access to walnuts in various properties we have worked in and in London you wouldn't get to see one ripen with the grey squirrels around. In the past when they were ripe they didn't split open in the same way they do in the Med. the same is true of almonds in London. They ripen but the fruit sticks to the stone.
Due to the squirrels and a taste for pickled walnuts we used to pickle them most years and they last for ages. We still have a few even though we haven't done any for several years. It is however very messy though easy. They are also very expensive to buy but cheap to make your own.

[David Bracey]

Sandra walnuts are beginning to fall but it is too early yet.

[Speedy]

I like green walnuts to make an Italian  liquer.

Nocino
Pick nuts at Christmas (Sthn Hemisphere) or june 24-25 in Nthn Hemisphere
24 nuts cut into quarters
10 cloves
1 nutmeg
1 cinnamon quill
rind of 1 lemon

put into a large jar 
and cover with 1litre 50% alcohol (grape spirit or vodka)
leave rest for 30-40 days.

strain and add 250-300gms sugar (to taste)
allow to dissolve and dilute with about 300mls water.

rest it for a week or so
and enjoy neat as a bit of a heart warmer in winter.