Reusing dirt from previous years flower pots - Ask Extension
I’m wondering if I should clean out my pots from this years flowers, and greenhouse plants. Last year I washed every pot, put in new dirt for the h...
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Reusing dirt from previous years flower pots #809423
Asked September 04, 2022, 3:50 PM EDT
I’m wondering if I should clean out my pots from this years flowers, and greenhouse plants. Last year I washed every pot, put in new dirt for the hens season.
what about using the dirt for these floweres and vegetables next year? If so, what’s the process for keeping it all healthy.
Kenai Peninsula County Alaska
Expert Response
Andrea-
This is a judgement call to which I will attempt to lead you to making your own informed choice.
First, the bottom line is that unless you clean (soap and water), then disinfect (10% bleach is common) your containers before reuse, you are likely to carry over bacteria and virus to next years soil and plants.
Using fresh, purchased soil media is the best common practice for avoiding soil born diseases and pests in next years pots/plants.
Reusing the soil (without treatment) will likely introduce, not only microbes, but also insect eggs, larva and/or adults to next years plants. Root maggots, weevils, aphids, slugs and cutworms are among the biggest concerns beyond microbes.
There are extreme treatment options (look up "soil sterilization") using heat or chemicals.
Also, I know some folks who seem to do well after including their soil in a HOT compost which, when done properly, should greatly reduce soil pathogens (they use for both pots and starter trays). Hot composting is the best practice even if adding to outdoor garden beds since we don't want those pest and diseases in those beds either.
Bottom line = if possible, to avoid headaches and heartbreak, use fresh media in clean containers every year.
FYI- A helpful publication on the full process for fall and winter preparation (including emptying pots) can be found by searching "UAF HGA-00429"
This is a judgement call to which I will attempt to lead you to making your own informed choice.
First, the bottom line is that unless you clean (soap and water), then disinfect (10% bleach is common) your containers before reuse, you are likely to carry over bacteria and virus to next years soil and plants.
Using fresh, purchased soil media is the best common practice for avoiding soil born diseases and pests in next years pots/plants.
Reusing the soil (without treatment) will likely introduce, not only microbes, but also insect eggs, larva and/or adults to next years plants. Root maggots, weevils, aphids, slugs and cutworms are among the biggest concerns beyond microbes.
There are extreme treatment options (look up "soil sterilization") using heat or chemicals.
Also, I know some folks who seem to do well after including their soil in a HOT compost which, when done properly, should greatly reduce soil pathogens (they use for both pots and starter trays). Hot composting is the best practice even if adding to outdoor garden beds since we don't want those pest and diseases in those beds either.
Bottom line = if possible, to avoid headaches and heartbreak, use fresh media in clean containers every year.
FYI- A helpful publication on the full process for fall and winter preparation (including emptying pots) can be found by searching "UAF HGA-00429"
