Dirt is Not Cheap
Gardeners can spend a lot of money on soil. Bagged dirt, whether organic, potting soil or compost isn’t cheap and it’s a little daunting to think you may have to start from scratch every year. But with a little effort, container garden soil can be reused without worry about contaminating your new beds.
First know it’s generally okay to reuse potting soil if whatever you were growing in it was healthy. If you had problems with pest or disease, you will want to sterilize it to avoid infecting new plants. And you are going to need some black garbage bags or black plastic storage bins to reuse your soil.
Step 1: Remove Dead Plantings From This Season
Pull out any dead plants that remained healthy and set aside for your compost heap. Turn over your containers’ dirt on old cardboard boxes that have been flattened, if you can. Remove any roots or leaves by finger combing the soil.
Step 2: Kill Bugs and Pathogens in Your Container Garden Soil
- If the plants remained healthy in the container:
Place the soil in black plastic bags, tie them tightly and leave them in the sun for 4-6 weeks. The heat builds up inside the bags just enough to kill bugs and pathogens. We leave our bags in the same area we have the containers (which gets the full sun for 6-8 hours daily), to avoid lugging the bags around too much. - If the plants did not remain healthy in the container:
It’s been recommended that you sterilize this 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. Check the soil temperature with a candy or meat thermometer to make sure it stays below 200 degrees, as higher temperatures can release toxins. When it’s done, take the soil out of the oven and keep it covered until it cools.
Alternative Heat Option
Microwaving is another option. Moisten the potting soil in quart-size, microwavable containers. Cover them with lids with ventilation holes or loose paper towels to allow steam to escape. Heat at full power for about 90 seconds per two pounds of soil. When it’s done, take the soil out of the microwave and cover up the vent holes until it cools.
While we have not personally tried this method, after cooking the soil, I think I would still place it in garbage bags for a period of time AND keep this soil separate, just in case.
What If Your Container Garden Soil is Contaminated?
If you are reluctant to go through all this trouble to reuse soil that may be ‘contaminated’, you can always use it to fill in your yard holes or level out erosion areas.
Step 3: Replenish Nutrients in Sterilized Soil
Once the soil has been sterilized, you need to replenish the nutrients that may have been lost in the spring/summer plantings. You can add fertilizer or stir in new potting soil, but personally we would recommend using your own composting. Store your renewed potting soil in a clean covered trash can or covered plastic buckets until it’s time to plant again.
Start Planning For Your Next Planting Season
So now you’re in a waiting game. This will give you the time to sit and study your garden area and decide what you’ll do for next season. Will you rearrange your garden? Will you expand your garden? Might you plant something different than you planted last season? While sitting and contemplating your coming-year planting decisions, you might want to enjoy a hot toddy or a cup of cold brew coffee to keep you warm as you muse about how your garden will bloom next spring.
Please Leave a Comment: Container Garden Soil
Leave a comment below and let us know if this information was of value to you or tell us what we missed and can add to this post. Tell us what you may be thinking about for your spring plantings and how you’ll use your renewed soil. We love photos. Add a picture to your comment to let us see your patio/garden area.
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