Growing fruit trees from the pits or seeds of the fruit isn't very difficult. Most fruits, including plums that you purchase at the grocery store, were produced on hybrid trees--where the root-stock of one variety is grafted to another variety. This means that you may never get fruit from your tree or it may not taste the same as the fruit you ate to produce the seed. The best way to be as sure as you can be to getting a like kind plum is to pick one or two from a tree nearby your home. Your tree may take between 5 to 7 years to produce fruit.
Eat the plums and take out the pits. Wash them off in warm water, removing any leftover flesh and place them on your counter or windowsill to dry.
Fill small plastic flower pots with potting soil. Place a pit into each container 2 inches deep and cover the tops with wire mesh.
Dig holes in your garden or a sunny place in your yard. Place the container in the hole and cover lightly with soil. Leave the container there for the winter. The seed should be protected from squirrels and other rodents by the wire mesh.
Mark the location of each container you've planted. Watch for small sprouts to come up in the spring. When this happens, dig up the containers and transplant the seedlings into larger pots using a three-parts potting soil to one-part compost mix.
Keep the tree in a sunny location outdoors and water when the top of the soil dries out. Bring the tree indoors if there is any threat of frost during the winter and place in a sunny window.
Dig a hole slightly wider than the container and the same depth in a sunny, well draining location the following spring. This will be the plum tree's permanent location so make sure it has room to grow.
Carefully remove the seedling from the container and place in the planting hole along with the soil. Fill in around the tree with potting soil and water to settle the soil around the roots.
Water well to help it get established to its new surroundings and then only when the top of the soil feels dry.
Fertilize with a slow-release fruit tree fertilizer each spring. Follow manufacturer's direction on amount to use per age of the tree.