Refreshing/reusing potting mix in SIP containers

[luigiwu]

I know potting mix can be reused for a couple of years with the proper re-supply of amendments etc. But do you find yourself coming across certain containers that are so fulll of roots that you can't use any of it at all? I'm curious about pple's experience with the earthboxes and the containers I use are 5gallon buckets.

I've also heard that most potting mix in SIP containers need to be tossed after 4 years as they stop wicking properly since the peat has broken down in that time.

[schill93]

Originally Posted by luigiwu

I know potting mix can be reused for a couple of years with the proper re-supply of amendments etc. But do you find yourself coming across certain containers that are so fulll of roots that you can't use any of it at all? I'm curious about pple's experience with the earthboxes and the containers I use are 5gallon buckets.

I've also heard that most potting mix in SIP containers need to be tossed after 4 years as they stop wicking properly since the peat has broken down in that time.

Can't answer your question about the invasive roots as I haven't been there yet. But as far a mix goes, according to the Earthbox forums, they say the mix should last for around 7 years. Now that holds approx.20 gallons so perhaps a 5 gallon has a shorter life but not sure why that would be.

[jmsieglaff]

Originally Posted by luigiwu

But do you find yourself coming across certain containers that are so fulll of roots that you can't use any of it at all?

That's what happens to me and I dump the entire contents into the community yard waste pile that gets composted.

I'd like to reuse it because of the cost of potting mix, but oh well, the delicious tomatoes make up for it in many ways in addition to the cost.

[ricman]

Hello luigiwu,

I reuse all of mine that I can and refresh with new mix. Sometimes I will have a bag that is a mass of roots and these I rototill into my regular garden spot.

[fonseca]

My containers all have worms living in them, so I don't have leftover roots for long. I never added any, but the brand of castings I use always seem to contain viable eggs, and since I reuse my mix, there are always worms.

When the season is over I usually dump all the 3-10 gallon containers into a giant pile on a tarp. I'll water in a few compost teas to maintain moisture. Sometimes I'll water in alfalfa, kelp and molasses tea to keep things active. I'll use up the last of any fungal inoculant remaining, as I buy a few ounces a year. I have had piles heat up before, so I try not to overdo it as I don't want to drive away the worms. This is in a shed and not exposed directly to the elements.

The following spring I will rebuild this mix with around 30% new material, mostly compost and a small percentage of peat. Coir and coir fiber lasts years so that doesn't get replaced often. Depending on the age of the mix and how it looks, it will get additional structural components added in. I have seen recycled soil mix recipes on forums that call for 50% spent mix.

Small containers need to be emptied if you want the roots to break down naturally. An indeterminate tomato in a 5 gallon container grows a dense root system. If the above seems like a lot of work, you could use a product like Hygrozyme. It's marketed for hydroponic systems, but before I went organic I had fantastic results using it directly in containers without emptying them.

I'm scared of pythium, and dead roots are a food source, so even when I had to screen a few hundred gallons, it was well worth it as a preventative measure.