Saturday, April 17, 2010

Fails from the Bucket: Planter-Finishing SIP

Yeah, okay, after the bucket. And only a small test, as I was pretty sure this wasn’t a brilliant idea. Sometimes, you have to try anyway. If it had worked, imagine the time I could save!

A little background for you lucky folks with in-ground gardens: an SIP, sub-irrigation planter, is a planter with no bottom drainage by design; instead, it has a water reservoir at the base, with some sort of wicking system to draw water from the reservoir to the planting medium. It encourages strong root growth, conserves water, discourages weeds, and can increase harvests dramatically (though some herbs and hot peppers will not develop full flavor grown in SIPs).

My personal preference is for clay pot irrigation, but SIPs run a close second, particularly the designs that can be tossed together in a few minutes from materials already on hand with no other tools but my trusty cordless drill. Beginning with an empty planter, it’s really no trouble at all, and repays the forethought all season long. Here in Austin, where drought is more the rule than the exception…

So where’s the fail? I tried a standard post-bucket bokashi technique in an SIP. Out of curiosity. Sandwiched a layer of cured bokashi between two thicker layers of soil based potting mix in the newly constructed miniature SIP. Didn’t water the soil in at all, but filled the reservoir completely.

This was not a good idea. The whole point to an SIP is that the wick delivers water to the soil, so there was an excess of moisture in the mix in only a couple of hours. Not mud, just too much moisture for the EM and soil-borne microbes of choice to do their thing, so some of Nature’s more water-tolerant digestors showed up to help out.

Yeah, that’s polite for insects.

This isn’t to say I won’t keep adding bokashi to my planters; I will. It just means that, in the case of SIPs, I’ll either be constructing them without any water at all (using the right wicking system, this should be possible with a moist mix kept covered for the finishing period), or I’ll use composted or otherwise finished bokashi rather than finishing it in situ. Which has always seemed like a more efficient process to me anyway—when putting it directly into a planter, you can only use one third the total volume of your container, but in a trenchless bucket set-up, you can use half, or even a bit more, if your soil (not potting mix) is particularly healthy. You just can’t use very wet soil, or get the soil wet too soon.

Ah, well; it’s a process, gardening.

Happy microbing,


image from Inside Urban Green, where simple instructions for building SIPs can be found.

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