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Can I Reuse Potting Soil?
You use a quality organic potting mixture labeled “food safe”. In fact, it’s intended for edible plants such as fruits, vegetables, herbs. However, when changing containers or simply repotting to loosen roots, that mixture often ends up in the compost heap. You might wonder, “Can I reuse potting soil?” And if so, what preparations should I take when doing so? [Sources: 2]
Every time we reuse the same potting soil for container gardens, we need to understand that most likely, the previous plants exhausted the nutrients. Those plants needed to use everything stored in the soil, leaving it depleted of many or all necessary nutrients. If you simply reuse the same soil, your newly established plants suffer poor nutrition.
Of course, you might empty your houseplant soil into your outside garden plot. You then add more nutrients to it, allowing for true reuse. And for people with an outside garden area, that works well. What if you don’t? [Sources: 9, ]
Instead, many keep only indoor plants. And, when using it for repotting houseplants, consider that this now nutrient-poor soil allows plants to be more susceptible to diseases. And, in fact, that disease might already exist in the soil, just waiting for the opportunity to infect an unsuspecting newcomer.
Can I reuse potting soil? Yes, But…
The reuse of potting soil is possible. However, you need to take a few steps to ensure that it can sustain the life of plants in the container you grow. [Sources: 0, 8]
All experts we spoke to agreed that potting soil reuse makes sense. However, they also warned about potential problems and effects. Simply stated, if you reuse the soil under the right conditions, make it free of any pollutants that could harm the plants. [Sources: 4, 8]
In order to learn the correct way to recycle and use soil for the container garden next season, I have written a short tutorial on how to recycle pots of soil. You take old plants and let them be reused as potting soil. [Sources: 8, 13]
And so, proceed with the reuse of your soil if it is not home to a diseased plant. To reuse soil from a plant, modified soil is required. [Sources: 1]
If you are not enthusiastic about the idea that your new plants were planted in old soil there is another way to reuse them. You can spread the old soil under a tree or in a garden bed. Add compost that can be used to plant vegetables, or just put in the soil. [Sources: 13]
With careful attention and little effort, potting soil can be reused. Thus, you save yourself, the intrepid grower,- a few dollars on the road. If handled carefully, you can even reuse it for the next few years and use it to solve other garden problems. In fact, proper reuse of potting soils can save you money and the trouble of pulling out a fresh bag of potting soil in each growing season. [Sources: 5, 7, 8]
Purchasing new potting soil every year to ensure a healthy medium can be a costly undertaking for those who depend on container gardening to top up their annual harvests. While you require a certain amount of new soil to keep your plants healthy, reusing old soil can be an effective and easy way to keep costs down. In some cases, revitalized potting soils can be used to mix old soil with fresh, equal parts, which is a safe way to ensure productivity and nutritional balance. [Sources: 7, 11]
Many gardeners mix used potting soil with new material and use half or a few handfuls of organic fertilizer for an additional boost in plant nutrition.
But resist just throwing the potting soil into the compost and replanting in those pots. Instead, scrub your large, disease-free container and sterilize it with a mixture of 1 part bleach to 9 parts water to prepare for the next season. In a similar fashion, you might also use the old pots from plants you gave away or shared, such as daylilies, bee balm, and other perennials. [Sources: 0, 5, 14]
Sterilize everything. In this way, you protect new plants from pests and infections lurking in the soil. As soon as you are sure that the old pot mixture is completely exhausted, throw the loose soil into a garden bed. In rare cases, when there is a lot of loose soil, remove the plants a little and store them with the lid in the remaining container until they are nicely dry the next time. [Sources: 2, ]
Use The Sun
Just as you cook or bake food to a certain temperature to destroy pathogens, you might cook them out of your soil, too. In fact, this way safely destroys weeds, seeds, insect eggs, larvae, and pathogens. That’s right; bake the soil in the sun. For reuse, sterilize the soil under the sun and cover it with plastic wrap for 4-6 weeks. [Sources: 10, ]
Break open the soil and rake it into your raised bed to add organic material and break up the available nutrients. You can then apply your old earth to it to dress the raised bed.
By rehabilitating your soil, you come to a step closer to creating a natural plant cycle. With just a few ingredients, you can turn depleted soil into the fertile soil you need to plant successfully. However, follow the right steps to ensure success. Otherwise, you might fail the next time you try to use old potting soil for new plants. [Sources: 0, 6, ]
What About Nutrients?
When using recycled potting soil, consider this. Many of its vital minerals have been absorbed and leached by plants from the previous year. Indeed, consider them completely or nearly gone. Also, you need to ensure that the soil is softened and agitated to provide good drainage. [Sources: 0, 1, 6]
Most potting soil mixes contain some form of compost. However, adding more compost to a mix with perlite provides additional nutrients. It also ensures a loose, fluffy structure to allow roots proper space to grow. Garland says that if you use the same potting soil, you should refresh at least a tenth of the larger container with new potting soil. [Sources: 14]
If you are an avid gardener and own several plants, you know that you will end up with plenty of soil to plant. Potting soil contains organic substances such as twig moss, compost, and worm castings that create air pockets to improve drainage. Other possible natural additives include vermiculite, perlite, and rice husks. Many contain moisture-retained crystals such as coconut coal. [Sources: 4, 8, ]
Keep in mind that your potted plants might become infested with diseases and molds. Then these might transmit to other plants if you reuse potting soil without special care. To reuse potting soil, carefully sterilize it. This ensures the removal of any contaminants. Then, aerate it well, and infuse it with new fertilizer or compost.
In doing so, your freshly potted plants receive the best advantage to new growth throughout the season.
Sources for reference (Can I Reuse Potting Soil?)