One of the biggest blocks to people planting walnuts is the lack of reliable descriptions of cultivars commonly available in the UK. Almost all descriptions of individual cultivars are copies of copies often, of a translation from another language.
I’ve put together a summery of some of these common cultivars with the common descriptions (amalgamated from various sources) and then a brief summary from our experiences. Note that we are in a very cold part of the UK that is fairly dry and is prone to spring frosts, we rarely escape April frosts and mid May frosts are not unknown.
This is not an exhaustive list, we have another 40 cultivars not on it and there are hundreds more worldwide, these are the ones often seen for sale in the UK. Our trees are very young but we see orchards all over the UK so have some experience from other micro-climates.