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Wondering how to store potting soil? I’ve tried a lot of different techniques for potting soil storage – everything from proper airtight storage to just leaving it in the garage and hoping for the best. Here’s what has worked well for me.
Potting soil is best stored sealed in its original bag, inside a protective container like a storage tote. Large plastic bins like Sterilite clear tubs and
Read on to find out exactly how I store my potting soil during the growing season and over winter.
Fall is the perfect time to get organized to store your potting soil. Take stock of your current unused potting soil supplies. Are there leftover bags in the garage, by the garden, or in the shed? What about the basement? Get them all together so you can take inventory of your unused potting soil and decide what to do with them.
Here’s exactly what to do in the fall to store potting soil for the winter.
Inspect each bag of potting soil. Take note of which bags have been opened. Recently purchased bags that haven’t been opened are generally the most desirable for storage, as they’re less likely to be contaminated. Some may have a printed expiration date, and others won’t.
Sift through all the open bags and check for insects, bugs, grubs, eggs, and mold. Any leftover potting soil in open bags that looks compromised should be put to use instead of stored. This includes potting soil that’s been exposed to animals, that’s got bugs in it or has visible mold on it. It’s not that this soil is necessarily toxic or anything, but it’s better off going through the compost than being stored for later use as sterile potting soil. Only save potting soil that’s worth saving.
Either make sure the potting soil you’re saving is nice and dry or set it out somewhere dry to allow the moisture to escape. This is key to avoiding mold and mildew issues in storage. Dry soil stores better, like dry pasta or dry cereal. Open the bags to the air for a few days and give them the odd shake or stir to help them dry out.
Store potting mixes in their original bags or containers so you will know the ingredients and manufacture date when you pull it out next season. Write the date on it if it doesn’t show a manufacturer’s date.
The plastic bag that potting soil comes in is wonderful because it has a label, but also because many smaller bags have an airtight seal. The big potting soil bags are often quite thin (and frankly sometimes have holes in them in the store), but the smaller bags are thicker and made to last.
Having an airtight ziplock at the top of the soil bag is great because it means you can just place the potting soil in any old box. If the potting soil isn’t in an airtight bag, you’ve just gotta accept that it won’t keep as long (or find a fancy airtight storage container (…more on that later).
The big thin plastic bags that potting soil is sold in are not really meant for long-term storage. The smaller pouches are better but still can tear (or be opened by kids, dogs, et cetera). Soil stored in its original bags should be put inside a solid container in homes where it might not last in its sealed bag!…(kids, pets…)
So now for the storage tub. Many gardeners use solid-colored Rubbermaid to protect the contents from sunlight. Some people prefer clear containers so they can see what’s in them. Consider your own circumstances and preferences on that one. Either one is going to be better than leaving an open bag of potting soil out in the yard over winter.
Clean and dry the tub (or whichever more aesthetically-pleasing bin you’ve chosen). Remove any dirt/debris and sterilize the tubs to minimize the transfer of unhelpful bacteria, fungi, or viruses. Some gardeners use a weak bleach solution. I just use a disinfecting cleaning wipe. The tub and lid should be allowed to completely dry after cleaning.
For each opened bag you’re saving, coax the air out of the bag and seal the opening with tape. You could use a big ziplock that seals, but I prefer just to tape the top of the bag shut. When all the potting soil is in the storage bin, close it with the lid.
If you have a bunch of different bags and don’t mind them being all mixed together (without labels), it’s also fine just to dump the contents of all the bags straight into an airtight tote. I can’t bring myself to do this because I like keeping them all separate, and I just use regular totes which are not at all airtight. Whatever works for you if you’re ok with the risks of the storage not being airtight.
And label the outside of the tote!
Store the potting soil tub in a nice dry utility area like your basement, garage, or garden shed. I like to store mine in my basement so it’s always on hand (and not frozen when I need it). It’s nice to be prepared for mid-winter seed starting or indoor gardening projects.
If you’ve got some kind of climate-controlled storage area, that would be perfect.
Wherever you store it, try to avoid places where it might get wet (especially places with running water or exposed to the weather). If your basement, shed, et cetera is damp, that’s not a good place to store potting soil either. I suppose this doesn’t matter if you’ve got a super airtight seal. Temperatures aren’t that much of a worry, though a cooler environment would be better.
It’s nice to set up a bit of a permanent solution for potting soil storage. It means less mess, less waste, and fewer issues with contamination in the long run.
It’s worth taking the time to store potting soil correctly because the sterile characteristic is one of the key differences between potting mix and outdoor garden soil. Soil absorbs moisture from the air if it’s not stored in an airtight location. While this isn’t necessarily a bad thing, it does compromise the sterility of the potting soil. If you’re bothering to pay money for sterile potting soil, it’s worth keeping it clean.
It’s nice to have some potting soil stored on hand so you’re not always having to buy a new bag of potting soil. It’s also hard to find potting soil in big box stores during the winter months in some areas. Storing fresh potting mix shouldn’t bring any critters into your house assuming it’s a decent potting mix.
The two things that have happened to my potting soil that wasn’t stored properly were:
Neither of these scenarios was much of a problem.
For the bag that the critters got into, I just tossed it into the giant compost heap we had at the time. The potting soil became part of our lovely homemade compost that we use as natural fertilizer all around the yard. It would be somewhat unlikely that potting soil would become contaminated in an organic garden with something so toxic that it wouldn’t be safe to compost. I’m sure it’s possible, but I’m not sure it’s likely.
The second bag of potting soil turned into daily soil toy truck hauling fun for my two-year-old. She loved using her hauler dump trucks and diggers to move it around the deck from various “borrow pits” to “construction sites”. I feel like I got my money’s worth out of that bag of potting mix, even if the poor container plant it was meant for would have liked to have it.
You can upgrade a storage tote to a nice potting storage bin if you like. Upgraded potting mix bins range from totally airtight to gleaming stainless steel. Whatever it is, it should hold at least a square foot of volume.
Airtight food storage containers can be an excellent choice. I ordered a pair of large pet food bins off Amazon and they work very well for storage. They even came with a scoop! There are also lovely airtight storage bins for flour and other baking materials. These could all work great for potting soil storage. I have even stored tiny amounts of potting soil in these adorable little stainless steel food tins.
Wood and ceramic can allow moisture to infiltrate, just as an unsealed plastic container can. Metal containers are often the prettiest option, but it is hard to find one with a seal. It’s fine if the container doesn’t have a seal, as long as you’re aware of it. Just make sure the bag is sealed, or know that your potting soil won’t last as long. Sometimes that’s a risk willing to take if the container is very pretty!
If the seal thing is becoming a big issue, you could also opt to store your potting soil in ziplock bags. I’ve found Ziplocs work very well for sealed potting soil storage. Just place the potting soil bag inside the Ziploc and then put the whole sealed thing in the pretty container. If this is too much of a mish-mash…perhaps just pour the potting soil into the Ziploc and keep the portion of the label that has the important info on it.
It’s fine to use potting soil from last year if it has been stored properly. Potting soil can generally be stored for a year, maybe two. If I found a potting soil bag from five years ago, I’d probably toss it in the compost. Some of my gardening friends would probably be just as happy to use old mix in their container plants. Either way, it can be put to use somehow.
If the potting soil hasn’t been stored well or is many years old, add it to the compost instead of using it in container plants. It won’t be wasted, but also won’t endanger your precious container plants. Running it through the compost is the responsible way to put really old potting mix to good use.
If you’re going to use old potting mix anyways instead of composting it, consider using it for outdoor container plants rather than indoor plants or vulnerable seedling baby plants.
Update – Here’s a helpful article with ways to use old potting soil. I had no idea it could be used in a worm bin. Thanks Andrea+Corey!
Be aware that despite your best efforts, your leftover potting soil might still contain nasty pathogens. Nothings perfect! That’s part of the risk of having a surplus of potting soil.
Some gardeners “sterilize” their potting soil in the oven. Just be aware that this can be rather smelly and unpleasant. I wouldn’t recommend “sterilizing” your potting soil like that.
I suppose you could steam it outdoors. I’ve never tried that…..it honestly sounds like a lot of work for a small benefit. But to each their own. This brings me to my next point…
Maybe just buy less potting soil next time?
I still have to remind myself of this EVERY SPRING.
I no longer “stock up” on potting soil. I can almost always find it at a good price if I shop around. It’s worth buying fresh each spring when the gardening sales start popping up in stores.
You don’t need that much potting soil in storage over the winter. It can usually be found in outdoor stores (even in wintertime) and always can be ordered online. I just keep one or two small bags now for wintertime.
At the end of the growing season, I put little bits of leftover potting soil from open bags in the compost with the autumn leaves to add a bit of variety to the leaf mold. Only unopened bags and other relatively un-compromised bags of potting soil are worth saving.
I keep enough in the house for little DIY projects, but not enough to be considered a “stockpile”. Just a small tote. That’s totally enough :)