I have an 8-year old (or so) chinese chestnut (at least that's what I was told it was when I got it for free from Friends of Trees) in my backyard and this year got a few (five pounds or so) nuts. Does anyone know if this variety requires two for pollination? there is another chestnut about a block and a half away, which might be close enough if they are bee pollinated, but probably not if wind pollinated...is that a correct assumption? Could I increase nut production by grafting a branch from that (or another nearby tree) onto mine, and if so what would be the best grafting method...I tried to do several three-flap grafts last year from three different trees I'd noticed around the city, but none of the grafts took, but that was my first attempt at grafting. What is the best time to collect scion wood/do the grafting here in the Pacific Northwest (Portland)