Now that killing frost has blackened the plants in outdoor containers, pots and planters, it’s time once again for fall cleanup. But what do you do with the potting soil that’s in the containers? Can it be left in the pots for next spring’s planting?
Used potting soil can be spread on the vegetable garden or flowerbeds to improve their soil quality, but those of us with frugal natures hate to see perfectly good potting soil dumped. Yes, it can be reused in next year’s planters.
I’ve lost track of the years, but Mary and I have used the same potting mix in some of our outdoor containers for at least 5 years; 7 years in some, with great results. When we moved our house a year ago to a new location, the pots tagged along, used potting soil and all.
Here are guidelines for reusing potting mix:
- Start with top-quality potting mix such as Miracle Gro Potting Mix, or the custom blends sold at locally owned garden centers. There is a huge difference in potting mixes, and it doesn’t pay to buy the cheap, heavy, poorly drained mixes. They aren’t worth using the first season, let alone trying to reuse for next year. The top quality mixes can be used for years, making them the better deal. Plus, plants like them better.
- When it’s time for fall cleanup, pull out plants, shaking the excess mix from the roots and back into the pot. If there are a few fine roots that shake off into the pot, that’s ok, but carefully remove any leaves and stems that have fallen onto the mix. Don’t allow leaves to remain in the mix.
- The mix can be left right in the pots, unless they are a breakable type that could be damaged if moist soil freezes and expands. We’ve never had a problem, and leave our mix in place.
- Leaving the pots outdoors, exposed above ground to winter’s coldest temperature is good for the potting soil.
- When planting time arrives next spring, remove about one-fourth of the old potting mix, and add new. Mix the new into roughly the top half of the planter, if the planters are large. This keeps the newer soil closer to the plants’ root zone. If the pots are smaller, just mix the new one-fourth in with the older mix.
- Many potting mixes, such as Miracle Gro Potting Mix, are blended with little beads of slow-release fertilizer. When reusing potting mix, this fertilizer is usually spent. You can recharge the nutrient content by adding Osmocote slow-release fertilizer. The label tells how much to add, depending on the pot’s diameter. Use slightly less, if you’ve blended new mix in that contains fertilizer.