Tips for Filling Garden Pots with Soil

By Charlie Nardozzi from Vegetable Gardening For Dummies, 2nd Edition

3 of 8 in Series: The Essentials of Container Gardening

When making a container garden, you fill pots with soil, stick in the plants, and add more soil. Here are some tricks to container gardening outdoors that'll help you grow healthy vegetables and ornamentals and save a bit of money, as well.

*Don't fill your pot with soil from your garden — even if your garden has the very best soil on the planet. Garden soil is too heavy and too "dirty" (you know, replete with weed seeds, bugs and their eggs, bacteria — stuff that you don't want in your pots), and it may not drain properly in a pot.

Instead, use potting soil (also called potting mix or container mix). Potting soil is well aerated, sterile, lightweight, and made of a good balance of organic material and mineral particles like peat, sand, or perlite. (Potting soil is actually soilless. That is, it doesn't contain any dirt.)

At your local nursery or garden center, buy a packaged, sterilized, soilless potting mix that's meant for container growing. If you need a large quantity, many nurseries sell potting soil in bulk. You may want to try different brands over time to see which ones are easiest to wet and which ones have the best moisture-holding capacity and drainage. But don't have a personal crisis over which brand of potting soil you buy; caring for your vegetables properly after you plant is more important than choosing the perfect potting soil.
Don't use potting soil to fill the whole pot. If you're growing plants in large containers, you'll be shocked at how much potting soil you need to fill each container. However, you don't have to fill the whole container with soil. Most vegetable roots penetrate only 10 to 12 inches into the soil. Add more than that and you're simply wasting soil.

A trick to use less soil is to put empty plastic soda and milk bottles in the bottom third of the container, and then throw the soil on top. The container will be lighter and easier to move, you'll be recycling to help the environment, and you won't have to buy as much soil.
Avoid using all the same soil each year. Planting in all of the same soil from last year can be bad news for your plants. Soil nutrition is depleted, and the soil likely has unwelcome diseases, fungal spores, and insects in it. Here are a few ways to reuse old potting soil:

Start fresh by replacing the potting soil in your containers each year. Throw the old soil into other parts of your garden.

Use the old soil in the bottom third of your pots and use new soil on top.

Empty out your pots and clean them. Amend the old soil with some new potting mix, and refill the pots.