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Earthbox or Earthtainer + 5-1-1 - Do I add the additional Lime?

Posted by redshirtcat 6a MO StL (My Page) on
Tue, May 17, 11 at 22:21

Al (or anyone with experience here?) I saw in a few very old posts that you suggested a 3-1-1 mix for SWC like the Earthbox or Earthtainer.

I've become quite comfortable making and using the 5-1-1 (thanks for all the help there, I have maybe 60 containers using 5-1-1 very well right now) - but I haven't tried any SWCs yet.

I made up a batch of 3-1-1 with 1 cup of lime (the usual rate for my batch size). My question is this: the Earthbox instructions say to take whatever potting mix we buy and add a large bag of (included) lime to it. Do you think this is necessary given that I've already added the usual amount?

I understand that you might not be an earthbox expert but can you see any reason why I might need more lime in this situation? Or do we think they are just assuming that most potting mixes do not include lime?

They also include a bag of fertilizer that they suggest we use in a "strip." I will probably use the strip in at least one earthbox to see how it goes - but can you see any reason why I shouldn't add my usual light dose of FP once or twice a week? Might it not work as well in an SWC/wicking situation?


Follow-Up Postings:

RE: Earthbox or Earthtainer + 5-1-1 - Do I add the additional Lim


I would follow the EarthBox instructions for that product faithfully. They have done a lot of research on the Lime and Fertilizer amounts and placement within their product.

Regarding the EarthTainer, I did trials with over 30 combinations of ingredients and I found for most vegetables, I got the best results with a 3:2:1 ratio of Potting Mix, Microbark, and Perlite.

Keep in mind that the wicking requirements for the SWC to operate properly (without any top-watering) require a higher amount of peat versus traditional containers where the 5:1:1 mix works well.


RE: Earthbox or Earthtainer + 5-1-1 - Do I add the additional Lim

Thanks Raybo! I didn't realize you were on this forum. I haven't paid much attention to SWCs until recently. As soon as I pickup the netpots tomorrow I will be building my first 2 Earthtainers in addition to the 2 earthboxes I'm trying. I will use the 3:2:1 in one of them as you suggest (with Pro Mix BX).

The Pro Mix is 85% peat which means that when mixed as you suggest the overall ratio should be something like:
42% peat, 33% pine bark, 24% perlite (assuming most of the the remaining 15% of the Pro Mix is Perlite, which is probably a bad assumption).

So if I want to build my own in the future it's something like 4:3:2 (peat, pine bark, perlite)?

RE: Earthbox or Earthtainer + 5-1-1 - Do I add the additional Lim


As Pro-Mix BX contains approx 14% Perlite as opposed to very little in Miracle-Gro, I would go with a 3:2:0.75 combo Mix, backing off a bit on adding new Perlite. This should give you a pretty good Combo Mix.

I use Sunshine Mix #4 myself as it is much cheaper than the equally good Pro-Mix, and use this recommended ratio.


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