What to do with potting soil in winter

What can you do with the dirt in your pots after your flowers have died?

Good news! You have a few options for what to do with old potting soil.

Let’s assume, for a sec, that your plants were healthy at the end of the season.

If yes…

Here are 4 things to do with old potting soil:

1) You can put the soil in a sealable container. Store it for next season.

An old garbage can works well because the lid creates a good seal and the wheels make it easier to move.

But any type of storage container that you can seal should work.

The nutritional value is gone from the soil, so you wouldn’t want to use it on its own next season. But next year, it’s possible to mix it together with fresh ingredients — like new potting soil or “compost.” (Compost is a mix of organic materials used to improve soil.)

This approach allows you to re-use some of your old potting soil.

Why use a sealable container?

It helps keep insects from laying their eggs and/or overwintering in your soil. (Yep, it happens.)

It keeps pathogens out — aka, things that could make your plants sick next year.

And it’s just an easy way to store it.

2) You may be able to take used potting soil to a yard waste drop-off program.

Many cities offer “leaf and yard waste drop-off” programs in the fall.

They’re a great way to dispose of the materials from your flowerpots, like your dead flowers and old soils. And the materials you drop off will be used to create compost, which is good for our soils and plants.

The companies that do commercial composting have machines that can heat the soil and leaf material to very hot temperatures, so the compost can be safely used next year.

To see if your city offers this type of program:

• Look on your city’s website OR check nearby cities. Some cities only make these programs available to their own residents. But other towns make their leaf and yard-waste drop off services available to anyone.
• Search for words like, “Leaf drop-off,” or, “Yard-waste drop-off.” Often times, these programs aren’t advertised as composting programs.
• Read up on what’s allowed for yard waste. Dead flowers are usually allowed, but make sure they’ll take your used potting soil too. I usually take the potting soil with me and ask when I get there. (I’ve never had an issue, but I imagine it can vary by city.)
• Follow the instructions for the drop-off. For example, you may be asked to put your yard waste in brown composting bags. They look like tall paper bags. You often can find them at local hardware stores. Or, the instructions may say you can bring your yard waste in any type of container. They’re just going to have you dump it out — as was the case in the photo above.

3) You can add the old soil (and flowers) to your own compost pile.

Home composting is a topic for another time. But just know it’s another thing you can do!

4) You can mix old potting soil into your flower garden beds or spread it lightly across the top.

The dirt from your flowerpots isn’t adding anything beneficial from a nutritional perspective. Over the summer, all the good stuff left the soil with each watering.

But we have such tricky soils in the Rocky Mountain region — like clay and sand. The potting soil may help improve the structure of your soil in the ground.

That can lead to better water drainage for your plants, so they have happier roots.

And hey, it beats putting the soil in a landfill.

Here are a few tips:

• It’s easiest to mix old potting soil into areas that don’t have plants.
• But you also can spread a thin layer of potting soil on the ground near plants. Keep it away from the “crowns” of your plants. (The crown is where a plant’s stem comes up from the ground. It’s where the stem and roots connect to each other.)
• If you’re going to mix the old soil into the ground near existing plants like perennials (the plants that return each year), be careful where you dig. You don’t want to disturb their roots.

What if your flowers had disease issues at the end of the season?

Then, put ALL the contents from that flowerpot in the trash — including the potting soil.

Disease can carry over from one year to the next in both the soil AND on the flowerpots themselves.

It’s possible to accidentally spread last season’s issues to next season’s flowers.

You also may want to sterilize your flowerpots, so you can keep next season’s flowers from getting sick.

Are you the extra-thorough type?

It’s also possible to sterilize your old potting soil to reduce insect and disease issues. The University of California Extension has helpful tips on how to heat up your potting soil to the right temperature. (Scroll to page 5 of their PDF.)

Full disclosure, I’ve never done this.

But it’s worth considering if you had disease issues that could carry over to next season’s flowers, and you want to reuse your soil.

Cheers to you for exploring what to do with old potting soil and finding ways to use it in a productive way!

Related tips that may interest you:

• Is it better to empty your flowerpots in the spring or fall?
• What to do BEFORE you empty your flowerpots
• Flowerpot clean-up tips: Helpful steps to take
• What to do with outdoor pots in the winter, so they last for many seasons

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