Can you reuse potting soil after your flowers fade, temperatures drop, and you empty your containers and put them away for the winter? It’s tempting to keep and reuse what you have since replacing potting soil can be pricey, especially when you have a lot of potted plants. But this lightweight mix of compost, peat, perlite, and other materials doesn’t last forever.
Plants use up the nutrients in it as they grow, and the mix can become compacted and filled with roots. Sometimes pests, diseases, and weeds can take up residence, ready to pop back up when you replant in the mix. However, you can remedy these issues and get another use out of your potting soil with a little extra work.
It’s generally fine to reuse high-quality potting soil if whatever you were growing in it was healthy. But can you reuse potting soil that’s been home to pests? If you noticed pests or diseases on your plants, it’s best to sterilize the mix to avoid infecting next year’s plants. First, remove roots, grubs, leaves, and other debris from the old potting soil. Then, decide on the best method for banishing microbes and insects.
One technique for sterilizing soil is called solarizing. It involves putting old potting soil in lidded, five-gallon buckets (available at The Home Depot) or black plastic bags tightly tied shut and leaving them in the sun for 4-6 weeks. The heat builds up inside the buckets or bags just enough to kill bugs and pathogens.
You also can sterilize old potting soil in your oven. Place it in an oven-safe pan, cover with foil, and bake it at 180 to 200 degrees Fahrenheit for 30 minutes (the soil will produce an earthy smell). It’s also important to check the soil temperature with a candy or meat thermometer (available at Williams Sonoma) to make sure it stays below 200 degrees. Higher temperatures can release toxins. When it’s done, remove the soil from the oven and keep it covered until it cools.
Microwaving is another option. Put old, moistened potting soil in quart-size, microwavable containers. Cover them with microwavable lids that you can poke ventilation holes in or leave cracked to allow steam to escape. Heat at full power for about 90 seconds per two pounds of soil. Remove the containers, cover the vent holes with tape, and let the soil cool completely before using it.
Once your old potting soil has been sterilized, you’ll need to replenish its nutrients. You can combine equal parts of new potting soil with the old and add a dose of slow-release fertilizer pellets (available at The Home Depot) according to package directions. Or, you can mix in one part compost to three or four parts of your old potting soil. Besides adding nutrients that plants need, fresh potting soil and compost will help keep the mix from compacting.
If you’re storing your refreshed potting soil until it’s time to plant again, keep it in covered buckets or clean trash cans (available at Walmart) or tubs with lids (available at Target).
How Can You Reuse Potting Soil You’ve Sterilized?
Reuse your clean potting soil in containers for vegetables, flowers, houseplants, or whatever you’d like to grow. If you’re not up for sterilizing and refreshing old potting soil, you can still put it to use instead of throwing it out. It can be dumped directly out of your containers and into established beds and borders. You can use it in raised beds or wherever your yard has holes or eroded areas. It can also be mixed into compost piles. The old potting soil you reuse can help you save money for what all gardeners want: more plants.
It's generally fine to reuse high-quality potting soil if whatever you were growing in it was healthy. But can you reuse potting soil that's been home to pests? If you noticed pests or diseases on your plants, it's best to sterilize the mix to avoid infecting next year's plants.
Yes, it is generally okay to reuse potting soil with proper care and rejuvenation. Reusing potting soil can be sustainable and cost-effective, but it's essential to refresh it by replenishing nutrients, adjusting pH levels if needed, and improving its aeration and drainage properties.
Opened bags of new potting soil can retain quality for around 6 to 12 months. For unopened and unused potting soil, you can store it for about a year or two before it goes bad.
You can refresh old potting soil by blending it with new potting soil. How? Create a 50-50 mix of old and fresh soil to use for your potted plants, mixing the two soils well to prevent compaction and root suffocation. That said, simply mixing the two soils may not give you the best results.
Plants typically benefit from being repotted every 12 to 18 months, depending on how actively they are growing. Some slow growers, like cacti, can call the same pot home for years, but will just require a soil replenishment.
If plants died from bacterial, fungal or viral disease, then you definitely do not want to reuse the soil, as soilborne pathogens can still be present and active. However, if the plants that grew in the soil before were healthy, it is generally OK to reuse the potting soil.
Steaming: Steaming is considered one of the best ways to sterilize potting soil and should be done for at least 30 minutes or until the temperature reaches 180 degrees F (82 C). Steaming can be done with or without a pressure cooker.
If your potting soil starts to smell sour, foul, or rotten, it's a sign that the soil has likely gone anaerobic due to overwatering or poor drainage. Anaerobic conditions can be harmful to plant roots and hinder plant growth.
Simply add organic debris to the soil surface and let your “underground herd” break it down. As it does, it will improve your soil's texture and make nutrients available to your plants. So don't be shy about applying copious amounts of organic residue to your soil.
Thankfully, there is one method that will consistently rewet super dry potting soil; wetting and mixing it with very warm or hot water and then hand turning and mixing it (be sure to wear water-impermeable gloves). The heat helps the peat and compost easily take up water again.
“Another option for gardeners who have larger containers is to remove only the top 6 inches or so of the old potting soil and replace it with new potting soil,” he said. “Since they aren't replacing all the soil, they're saving money while still refreshing the upper area, which will aid in root growth.
We recommend letting most newly-transplanted houseplants – especially cacti and succulents – go a few days without additional water so their new roots can breathe and begin growing into their new space. For moisture-loving plants – like maidenhair fern, for instance – you'll need to water sooner.
Yes you can reuse soil with roots in it. However, try and remove as many as possible. Especially the larger roots left behind. Leaving some smaller ones shouldn't hurt anything.
Most garden spaces that are used year after year only need a little compost, which can be added on top and lightly mixed in with a digging fork. “Just place a layer on top of the soil, and work a little into the soil with the fork,” says Sluis.
Key takeaways: Here we are spilling the answer – The potting soil mix that is considered great for the pot is absolutely good to be used in the ground. It also improves the aeration in the soil and moisture retention.
Introduction: My name is Rev. Leonie Wyman, I am a colorful, tasty, splendid, fair, witty, gorgeous, splendid person who loves writing and wants to share my knowledge and understanding with you.
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