Plums are a popular fruit that can be used in a number of different dishes. While they can be grown in small spaces, they do need some room to grow. Each plum tree needs about ten to fifteen square feet of space. This allows the roots to spread out and the tree to get the sunlight it needs. If you are growing multiple plum trees, you will need to space them out, so they have room to grow. In addition, you will need to prune the trees regularly to keep them from getting too big. With proper care, plum trees can produce a bountiful harvest for years.