Few things are more important than soil when it comes to gardening. While it’s tempting to buy new potting soil each year, it may be more environmentally and financially beneficial to reuse your soil instead.
But how long does potting soil last? And how do you prepare potting soil for multi-year use?
In this blog post, I’ll go over my approach for evaluating old potting soil and reusing it in containers.
Does Potting Soil Go Bad?
The short answer is yes, potting soil can go bad.
Potting soil is made up of a mixture of soil, compost, and other organic matter, as well as fertilizers and other additives. Over time, these materials can break down and become less effective at supporting plant growth.
Additionally, every time you water your container, a small amount of nutrients will be flushed out. Because of this, potting soil can become compacted and drained of nutrients if not properly cared for.
All of this can be addressed or prevented with the proper know how. So there’s no limit to how many uses you can get out of a particular batch of soil if it’s treated correctly.
However, the biggest issue with reusing potting soil is carrying pests and diseases from previous years over to new, healthy plants.
If you notice mold, infestation, or fungus in a container, the soil is likely beyond saving. The best course of action is to throw out the diseased soil and start with fresh potting soil in the coming year.
How to Prepare and Store Potting Soil
At the end of each year, I begin the process of preparing my soil for next year’s garden. The process usually looks like this:
- Remove plants and debris from containers.
- Store dry potting soil in air tight containers.
- Aerate soil once planting season arrives.
- Mix plant food into the soil right before planting.
I start by removing any and all plants from my containers, regardless of whether or not the plants are already dead or dying. Large root systems should be extracted as well, within reason. Don’t leave enough of the previous plant intact that it may come back! I also remove any weeds or debris that may be present in the soil.
Ideally, you’ll want to store your soil fully dried, in an air tight container that sits in a cool, dry place. I say “ideally” because, like me, you might not have such a space if you live in an apartment. The past couple of years I’ve left my containers outside all winter, uncovered, with the soil in them and it’s turned out perfectly fine. However, be aware that this approach makes it more likely mold and fungus could take root in your soil.
When I’m ready to start planting, I aerate the soil by mixing it up with a shovel. Aerating old soil is very important. It helps improve drainage and brings back some much needed oxygen. A fork or hand tiller also works well for this.
Once the soil is aerated, it’s time to add some nutrients back into the mix. This will help to replenish the nutrients in the soil and improve its overall structure.
I use Garden-tone organic plant food to restore nutrients to my containers, but compost could also be used instead. Make sure whatever compost or fertilizer you’re using gets mixed in really good with the soil! This will add some extra aeration, as well as ensure the plant food is evenly distributed.
And that’s it! Once everything is all mixed up, I start planting.
For me, recycling soil is the same amount of work as hauling fresh bags of potting soil home from the store. And as an added bonus, it helps me save money and reduce landfill waste.
Hopefully by following the steps I outlined above, you can begin reusing the potting soil in your container garden as well!