reusing container mix?

[hazeldazel]

My tomatoes are still growing strong in my 7 gallon grow bags but I was starting to think about end of season and next season. Can I reuse the mix or should I throw it out? Not seeing a lick of disease or pests so far.



The mix is coir+perlite, store-bought compost and a little bit of cow manure (I've been adding masterblend + calcium nitrate and epsom salts). I figure the nutrients will be used up and was planning to add some organic fertilizer (bloodmeal, bonemeal, and kelpmeal) for some long lasting nutrients next year. If it matters, I'm doing string trellising with the tomatoes pruned to one or two stems.


Thanks for the advice!

[AlittleSalt]

What many here have told me is that, yes you can use the same container mix. I have some fall tomato plants growing in containers that I used earlier this year. I use the Master Blend, Calcium Nitrate, and Epsom salt mix in one container. The other two containers - I've just been watering with no other help. The Master Blend, Calcium Nitrate, and Epsom salt mix plant is 4 times larger than the others. So my answer comes from seeing results, and it is that, "Yes, you can reuse that mix."

The rest of your question - I am also wondering about using organic additives in the winter/off season for next year's crop. I wish I could give you an answer, but I'm learning along the way too.

I left out that all three containers are growing Japanese Pink Cherry tomato plants.

[peebee]

A lot of folks here will refresh half of the potting mix each season, if they are reusing it at all. I've done so with mixed results. Since it's so wasteful to throw it all out, what I do is keep all the used mix in a designated big container, and I use that as the very bottom layer of all my new pots. But only a few inches worth. Then I put some chicken manure as the next layer and then add all new potting mix. I put the manure close to the bottom so the roots will have something to look forward to.

I also use the old mix to cover fresh stuff I throw in my compost bin, to ward off the flies and any smells. Another use for it would be in my garden beds; the perlite in it fluffs up the dirt and my flowers seem to like it. And my cacti and succulents seem to like it just fine with some pumice or more perlite added in.

Of course, the stuff tends to dry out so I keep it moist by either covering it most days and uncovering during the rare rainy days. And now I am growing more in Earth Boxes which requires new potting mix only every 2-3 years so I won't have much extra used mix pretty soon.

[ginger2778]

Originally Posted by peebee

A lot of folks here will refresh half of the potting mix each season, if they are reusing it at all. I've done so with mixed results. Since it's so wasteful to throw it all out, what I do is keep all the used mix in a designated big container, and I use that as the very bottom layer of all my new pots. But only a few inches worth. Then I put some chicken manure as the next layer and then add all new potting mix. I put the manure close to the bottom so the roots will have something to look forward to.

I also use the old mix to cover fresh stuff I throw in my compost bin, to ward off the flies and any smells. Another use for it would be in my garden beds; the perlite in it fluffs up the dirt and my flowers seem to like it. And my cacti and succulents seem to like it just fine with some pumice or more perlite added in.

Of course, the stuff tends to dry out so I keep it moist by either covering it most days and uncovering during the rare rainy days. And now I am growing more in Earth Boxes which requires new potting mix only every 2-3 years so I won't have much extra used mix pretty soon.

I haven't changed the whole Earthbox potting mix yet, been about 8 years now. I do remove the old fertilizer strip,add a new cup of dolomite, mix well, add a fresh fertilizer strip, top off with some new mix every year. This seems to add up to replacing about 1/5 per year.
I solarize them every summer because it's so hot that it's perfect and we grow in fall,spring winter.

[zipcode]

I reuse it for many years. Seems a massive waste to throw everything, not to mention I have nowhere to throw it (and it's also expensive). If you start with rough peat, the compactness doesn't happen for quite a while.

[hazeldazel]

Thanks for all the advice everyone! Since it’s so expensive to start new each year, I’ll reuse with additional fertilizer as long as there’s no disease.

[peebee]

Originally Posted by hazeldazel

Thanks for all the advice everyone! Since it’s so expensive to start new each year, I’ll reuse with additional fertilizer as long as there’s no disease.

I heard from one member who farms commercially, he solarizes his potting mix in large see-thru plastic bags each summer to ensure no diseases are lurking in it. I have solarized garden beds before but never potting mix. Luckily I never had an issue before where I had to, but it's an option for those out there who might want to look into it.

[Koala Doug]

One thing to be aware of is the build-up of salts in the growing medium.

[Tomzhawaii]

Originally Posted by Koala Doug

One thing to be aware of is the build-up of salts in the growing medium.

Aloha Doug,
What would be a good way to clean salts from coco coir ?
I could use any advice you might have.
Tom

[zipcode]

Originally Posted by Tomzhawaii

What would be a good way to clean salts?
Tom

Leaving it over winter in the rain. Depends how much it rains I guess, a few weeks of heavier rain should be plenty.

[ginger2778]

Originally Posted by Koala Doug

One thing to be aware of is the build-up of salts in the growing medium.

No buildup with organic fertilizer. I do use Calcinit and epsom salts as a supplement, so there is a tiny bit at the top,that thin layer is scraped off when I replenish.
My whole Earthboxes are solarized with a clear plastic bag completely sealed around them every summer.

[akgardengirl]

I reuse each year with an addition of fresh compost and sometimes perlite if needed.

[ScottinAtlanta]

Originally Posted by akgardengirl

I reuse each year with an addition of fresh compost and sometimes perlite if needed.

I do exactly the same.

[agee12]

I follow a similar routine as peebee.

I dump the used potting mix and from there I treat it like a compost pile. I add food scraps, leaves and non-diseased garden waste in it, turn it and add water. I am not very vigilant with making sure the the "pile" is hot or that I turn it and water it at proper intervals. Currently I store the used stuff in a giant bag, it is not a construction bag but close to it and a large garbage can (the curbside type) that I drilled holes in.

Then when I use it I tend to use it as the bottom layer in pots.

If it is a plant that does not require high quality growing medium, I may fill the entire container with the re-used medium.

At this time I only have one raised bed and I also mix the re-used stuff with the native soil.

Sometimes I sift the mix, I use a kitty litter sifter.


If you want to use all of the potting mix from a previous season I would follow what akgardengirl stated which is to amend the used potting mix with quality compost and, if needed, add perlite for drainage aeration.

[Antipodean]

As potting mix gets older the particle size of the ingredients get smaller as it decomposes/breaks down. And the result is that it compacts down more reducing drainage and porosity......it may still be okay for another season, but perhaps not as good as last season. What I would do is sift out the finer stuff out using fly screen and add some fresh coir.
Good luck!