More about Walnut trees
The combination of healthy unsaturated fats, high levels of antioxidants, and rich vitamin content has increased interest in growing nuts in the garden or home orchard. Somewhat surprisingly the humble Walnut is turning out to be perhaps the healthiest of all nuts, thanks to its super-abundance of antioxidants.
Walnuts are essentially large trees, and over the course of several decades will slowly grow to a height of between 6m-12m (20ft - 40ft) depending on the variety. Most of our Walnut trees are grafted on to rootstocks of a related species (the Eastern Black Walnut) which encourages earlier fruiting - even so they grow at a leisurely pace and regular nut production is unlikely to start before 4-8 years. However like most slow-growing trees, Walnuts are long-lived. Growing Walnut trees is therefore a long-term undertaking, but a worthwhile one.
Some Walnut varieties are self-fertile, with both male catkins and female flowers occurring on the same tree. In this respect Walnuts are similar to Hazelnuts rather than Almonds (which are more closely related to plums). The potential for self-fertility arises when the timing of both the flowers and catkins co-incides. Self-sterile Walnut varieties are those where the flowers and catkins do not overlap. Again, as with Hazelnuts, it is often a good idea to plant two Walnuts of different but compatible varieties if you have the space. Walnuts have an advantage over other nuts in that the pollination process occurs in late spring so is less affected by the poor early spring weather which often occurs in the UK.
Walnuts are relatively untroubled by diseases, but pruning is best avoided.