I am looking to transplant some flowers into a large pot. Would it be a bad idea to put something in the bottom of the pot to fill it up a bit, some mulch, rocks, a plastic bucket, or something? Or should we just get a lot of extra dirt? There are holes in the bottom, so drainage should not be a problem, but we would like to make the pot a little lighter in case we need to move it, and so we don’t have to buy and move as much dirt. The flowers are about 6-10″ tall, the pot is 2′ round by about 20″ deep.
The Gardener’s Answer
Hello, Roy in Colorado: Unless you are planting a larger tree or evergreen in a container, there is no reason to fill your container solely with potting soil. It can make the container even heavier than it already is and purchasing quality container mix can get expensive. So, yes, you can fill part of the container, one-third to one-fourth, with a different material that you might already have lying around. Mulch is a good choice since it is lighter, less expensive, and still allows for good drainage. Plastic bottles or even commercial nursery containers can be used to fill up space. The most important thing to remember is that the soil needs to be able to drain properly; blocking the drainage holes with large rocks should be avoided. As a general rule, annuals do not have extensive root systems. Since we change them out seasonally, they only need a limited amount of soil to grow in. If this is a planting that you intend on keeping in there for several years, it is a good idea to fill the entire container with potting soil.