Gardening in containers require the soil be light and airy as well as have good drainage. This allows the roots to grow and "breath" So should you reuse your soil?
In the years I have gardened I have had to use containers as I have a brick back yard that is about
15 by 12. I always felt you could reuse the "dirt" soiless mix for containers again, if you helped it the next year with admendments and cleaned it out of the roots and debris. This was, of course, if you did not have any disease in the growing season. Soil that has had diseased plants or may have overwintering soil dwelling insects and their eggs should be discarded. Garden sanitation is essential in containers as well as the regular garden.
This has always worked for me and I didn't reconsider until recently when I started reading answers to the question........Can I reuse my container soil? It was confusing to say the least.
Some say, just throw it on the compost pile. I don't have a compost pile.
Reuse it in your garden. Again no garden.
And yes recycle that soil unless the actual structure has changed over the years.
When I start my growing season, I dump all of the pots, clean them out with a light bleach solution and start my new soil mix. I add my amendments, manure, perlite and peat moss, more soiless mix and mix mix mix. I use dehydrated manure because I do not have a compost pile, perlite and peat moss.
If I find the soil looks and feels spent I dump it in the recycle bag and take it to my local composting site.
I finish with a mulch on top to retain moisture and fertilize through the summer. So far it seems to have worked OK. This year I am using coir and mushroom compost as it is supposed to be better. To be determined.
Rotation with vegetables is also recommended as you would rotate in a raised bed. Heavy feeders, light feeders and light are all considerations. Most of my pots are flowers so it is easier, I feel, than growing vegetables in those pots. Since I dump and start anew every year it is easier to not worry about rotation.
So can you reuse your potting soil? Yes and No. If you dump amend and reuse yes. If you leave it in a pot and keep reusing I say no. I am sure there are many answers and many conclusions. This is mine from my experience.
What's coir? Coir, pronounced kwar, is a rising star in horticulture. Also known as "coco coir" because it is made from fibrous coconut husks, coir is an effective, economical and earth-friendly addition or alternative to traditional peat-based blends.
From Fine Gardening
Getting to the Coir of the Matter
Gardeners for years have lined their hanging baskets with long-fiber coir. Learn how this material differs from peat.
So why would you choose one material over the other? One reason may have to do with your definition of a renewable resource. Peat comes from decomposed plant remains that have accumulated in waterlogged soils for thousands of years, and some people worry about diminishing peat bogs. Coir comes from a resource that many people consider more sustainable: coconuts.
The difference between peat and coir doesn’t end there. While peat tends to be acidic, coir leans toward a near-ideal pH, depending on the source. Some people also find that coir is easier to work with than peat. Coir retains more water than peat, making it a wise choice for many containers and hanging baskets. But the potential for high levels of soluble salts to accumulate is greater with coir-based than with peat-based soils. To eliminate any cause for concern, be sure to buy coir products from a reputable company.
Coir has been used for a decade in the United States by the commercial greenhouse industry and even longer by growers in the world’s tropical, palm-rich regions where it is produced, including Sri Lanka, Philippines, Mexico, and India.
Gardeners for years have lined their hanging baskets with long-fiber coir, and coir fibers are used to make common household items such as rope, doormats, and upholstery stuffing. Coir fibers are generated when the coconut husk is ground. Coir dust is the by-product of this process. Some of you probably have used chunks of coir dust to grow orchids, ferns, anthuriums, bromeliads, and other tropical plants.
Nutrient and pH differencesIn substituting coir for peat—whether using it alone as a garden soil amendment or in the potting mixes you make—be alert to possible differences in results. Coir is rich in potassium (K) and the micronutrients iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). The high potassium content means that a gardener could use a fertilizer that’s lower in potassium and still get good results. The other nutrients are a bonus—just like adding a vitamin pill to our daily diets. Because the pH of coir (5.5 to 6.8) is more neutral than that of peat (3.6 to 4.5), some gardeners may find that coir does not work as well for acid-loving plants, such as azaleas and blueberries.
Most gardeners are familiar with the challenge of wetting dry peat; coir is praised for being easier to rewet from a dry state. Overall, coir is a wonderful amendment if you want to improve the water retention of your hanging basket or container. Coir can absorb water at a rate of about seven times its dry weight. This is almost 30 percent more water than peat can hold.
While coir may not replace peat, it is nice to have a more easily renewable option. The positive qualities of this coconut by-product make it a natural fit in many garden applications.
The dos and don'ts of using coirDo
* soak a compressed brick, block, or bale in water for at least 15 minutes before using.
* make sure the soaking container is big enough; coir will expand five to seven times in volume. For a brick, which yields about 1/3 cubic foot of coir dust, a drywall bucket will do. For a bale (about 2 1/2 cubic feet), use a child’s small swimming pool or an outdoor garbage can.
* add coir to garden soil as an amendment, or use it as an ingredient in potting mixes. Like peat, it can account for up to 40 percent of the potting mix.
Don't* use bricks that fail to absorb water readily and expand.
* try to slice a brick in half. Even a chain saw won’t cut it.
* toss out any unused coir. It retains its properties and can be stored—covered— for several years.
Photo: Melissa Lucas
From Fine Gardening 105 , pp. 20