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Can I keep my used potting soil for spring, or should I throw it out? Here's what you need to know

Potting soil in pot
(Image credit: Shutterstock)

Your yard changes throughout the year with each season bringing its own challenges, and some of the gardening jobs you do to suit the changes in weather can become costly. But, one of the most expensive jobs is using potting soil to grow your container plants.

It's an expensive investment, but a necessity if you're eager for your potted plants to thrive. And when the cold weather rolls around and you're carrying out the winter garden chores to get your yard ready for spring, like disposing of old plants, you may be wondering what to do with the potting soil you've already used and have left behind.

Can I use potting soil two years in a row?

Preparing soil

(Image credit: Shutterstock)

It's pretty unlikely you'll be able to use the same potting soil two years in a row — and that's because it'll have used up all its nutrients to help your plants grow in around six months.

Potting soil is extremely advantageous to your container plants because of the nutrients it feeds to the plants, promoting growth and good health. But, once the plant has absorbed all the nutrients, there's none left to spare, meaning if you reused the potting soil, your next plant wouldn't be getting any of the benefits.

Not only would it lack nutrients, but it'd also be so full of roots from the previous plant that there wouldn't even be that much soil left to share when you sift through it all.

But, there is something you can do if you want to save just a little bit of money. And, before you say it, it's not to use the ground soil from your yard. We'd advise against that, because it's too dense for container plants to take root, and one of the big mistakes you can make when repotting a plant.

How can I reuse it?

Repotting houseplant

(Image credit: Shutterstock)

Try the 50/50 method

As discussed, potting soil isn't as nutrient-dense after it's already supported the growth of another plant. But, that doesn't mean it's all unusable. As long as the soil has been home to a healthy plant, it can be sifted through to eliminate all previous root and plant mass and mixed in alongside fresh potting soil, creating a 50/50 mix.

Note: If trying this technique, it's very important to not reuse any potting soil, no matter how tempting, if there has been any dead or diseased plants housed inside.

Bulk buy your potting soil

It's an inevitability that you'll need to buy more potting soil, since you can't reuse it all, or even any of it. So, if you know you're going to need potting soil, you should try bulk buying it to save money for the seasons ahead.

Like most things, buying them in bulk, if you've got the storage space, will save you money in the long run and will often cost you less to begin with. But watch out for extra delivery costs if you can't go and pick it up yourself.

Miracle-Gro Potting Mix
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For $17, you can pick up not one but two 16 qt. bags of potting mix ready to support your container plants, including flowers, vegetables, annuals, perennials and shrubs. It'll feed them for up to six months and with potting mix to spare, you can keep your plants thriving for even longer. Each bag is able to fill a 12-inch container, but check out our final reusing method to make it last even longer.

Fill the pot with recycling

It can certainly feel like a waste when you fill your entire container with potting soil, but your plants only need about 12 inches of soil to take root. Instead, you can fill up the lower part of your container with recycled containers like old cans and milk cartons.

Be sure to use a stretch of landscaping fabric over the top of the recycling though, otherwise you'll waste the potting soil that drops down into the cracks. As mentioned, be sure to leave at least 12 inches for soil above the recycling so that it can spread its roots effectively.


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Grace Dean

Grace is a freelance journalist working across homes, lifestyle, gaming and entertainment. You'll find her writing for Tom's Guide, TechRadar, Space.com, and other sites. If she's not rearranging her furniture, decluttering her home, or relaxing in front of the latest streaming series, she'll be typing fervently about any of her much-loved hobbies and interests. To aid her writing, she loves to head down internet rabbit holes for an unprecedented amount of time.

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