I want to plant a plum tree in my garden, but I have been told that I cannot just plant one tree, but two. Is this a way of making extra money out of me, or is there a real reason?
Why you need 2 Plum Trees by: Countryfarm Lifestyles
I am sure your nurseryman is very happy that you want to plant a plum tree, because you will need to buy 2 trees, not just 1. However, this is not because he wants to make extra money out of you, but because plum trees are a hybrid.
Being a hybrid means that many plum varieties are self-sterile. In layman's terms they don't pollinate themselves, they need another plum tree in flower at the same time to help the job along.
So make sure that when you do buy your second tree that it will flower at the same time as your first tree. It also needs to produce large amounts of pollen and must be a fruiting variety, not an ornamental variety.