Composting Potted Plants – Why & How To Reuse Old Potting Soil

If you are looking for ways to recycle and reuse your old potted plants and their potting soil, then composting is the way to go!

Now that the weather is turning cooler, most of your potted or container annual plants from the summer are likely starting to die off. Annual plants are only intended to live for one growing season and then they are done – no matter how much you might wish they could keep on blooming or producing!

Most of the time, container or potted plants die because of either old age or the weather. And, let’s be honest, there’s also the high probability of them dying from neglect or a lack of moisture because life tends to get in the way this time of year. (We can still blame it on old age though – for the plant that is!)

However, seeing the dead plant on your front porch can be rather sad. Not only did you likely spend quite a bit of money on the plants and potting soil, but it just seems like such a waste to toss it all into your trash. Sure you can reuse the container for next year’s plants, but what about the items inside that container?

What can you do with not only the dead plant matter but also the worn-out potting soil? That’s where composting the old potted plants and soil comes into play – with a few simple tips!

The Why & How Of Composting Potted Plants

First The Why

If you have gardened for any amount of time, then you know just how important compost is. It can improve your overall soil structure by adding loads of organic matter to the soil. It can also add power and nutrients to old, tired soil. Compost can even act as a natural mulch to help insulate and protect roots.

You can purchase bags of compost at the store or even in bulk at garden centers. You can also make it yourself. Not only is it easy to do, but you’d be amazed at just how many items you can compost.

I started making compost a few years back. I love how it has allowed me to keep so many materials out of the landfill. Between the compost pile and our chickens, we don’t end up with a ton of trash. Even if you don’t have a home compost pile, many local communities have municipal compost facilities where you can drop off your items. (It may be a small hassle, but it’s still better than adding them to the landfills!)

The Cost Of Potting Soil

It’s no secret that the cost of everything just keeps going up and up – and that includes potting soil. Every hanging basket, potted plant, and growing container on your property is filled with some type of potting soil.

If you are like me and have several different potted plants around, the cost can get super expensive! This is especially the case if you are purchasing potting soil in bags (which is what I usually end up doing). (Product link: Miracle-Gro Potting Soil)

But even making your own potting soil mixture from scratch can start to add up. That’s where recycling your old potting soil can come into play.

By composting both the potted plants and the potting soil, you can recharge the soil and give it new life again. This can save you money in the long run. In addition, it also makes it seem like purchasing it in the first place wasn’t all for nothing.

Why You Can’t Reuse Old Potting Soil “As Is”

While it might be tempting, don’t reuse old potting soil “as is.” After an entire year of growing flowers, vegetables, or whatever you planted, the soil is likely completely void of nutrients.

Even if you add supplemental fertilizers or compost throughout the growing season, the soil itself will struggle to support another year’s worth of growth. After a growing season, the overall structure of the soil becomes dry and hard.

You may have noticed this when you go to water those older potted plants. As you water, it seems to immediately strain out of the bottom with none of it really soaking in. This is usually because the plant is so rootbound or the soil structure is just lacking overall.

If you were to remove this plant from its container, you will likely immediately see what I mean. Instead of the soil gradually spilling out in loose pieces like it was when you added it, it keeps the same shape as the container. (Kind of like how packed brown sugar comes out of a measuring cup.)

Using the soil as is next season will only result in struggling plants. Not only will the plants not be able to grow and thrive, but they will also be much more susceptible to pests and diseases.

So, instead of using it as is, you can add it to your compost bin and recycle and recharge it. By the time the next growing season rolls around, your old, depleted potting soil will be turned into amazing, nutrient-packed compost that can be used in conjunction with potting soil or added to your entire garden!

Composting Old Potted Plants – The How

This step might seem pretty self-explanatory (just dump the potted plants into the pile, right?). However, there are actually a couple of things to keep in mind before adding old potted plants to your home compost pile.

The first is to not add any plants that are diseased or currently have pest issues. Home compost piles typically cannot heat up high enough to kill off any pathogens or pests that might be lurking on the old potted plant. When you add those plant materials to your compost, you are setting up the entire pile for trouble!

In those cases, the best bet is to dump the old potting soil and plant material in a place far away from your garden or current compost pile. Another option would be to burn the materials.

Next, you want to make sure to remove any seed heads that might be present on your potted plants. For example, if you were growing sunflowers in containers, remove the flower heads before adding the rest of the plant and the soil to your compost pile.

Just like how your home compost pile can’t get hot enough to kill off pathogens, it also can’t get warm enough to kill off seeds. Once you go to use the compost next season, you are essentially “planting” seeds anywhere you use the finished compost.

Chopping It All Up

The next tip is to chop up the old dead potted plant and its roots into pieces. As with anything you add to home compost piles, the smaller the pieces the quicker the materials will break down and decompose.

The same goes for composting old potted plants. Most container plants will be rootbound by the end of the growing season. That root mass will hold its shape and take forever to decompose if it isn’t broken up a bit first. The plant itself might also have long, scraggly stems and leaves that need to be broken up into pieces.

Use a sharp gardening knife or shovel to help tackle this task. I typically use my hand trowel and it worked fine for my smaller potted plants.

Turn The Pile Often

In order to get the pile to decompose and break down the old potted plants and potting soil quickly, you need to turn the pile frequently. Ideally, you want to turn the pile at least once a week.

Now, does that happen with my home compost pile? Not really! I use a two-bin system where I have finished compost on one side. So I am not really in a huge rush to get the new materials to break down before spring.

However, if you hope to have any chance of using it quickly, turn it often. With proper turning and following the other tips that are in my “Making Compost The Easy Way” article, you can have finished compost to use all around your property next year.

By composting your old potted plants and the potting soil, you are keeping as many items out of landfills as possible while powering future plants and improving your soil at the same time!

Until next time, thanks for stopping by!
– Chelsea

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