When you choose a planter, make sure that it's stable. Some planters are tapered, with the bottom significantly narrower than the top. The shape plus the weight of your growing plant can make tall planters top-heavy. In this case, it's best to balance the weight by adding a heavy filling material at the bottom. If you don't like to make the planter very heavy, such as when you plan to move your planter around a lot, you can also use tie wires to anchor these planters. This way, even when your kids or pet bump into them, the planters will stay in place.