Recap of the May 20th SIP Workshop

Last night, a small group gathered for a hands on workshop at Mr. and Ms. H2's urban hideaway.

She passed on these captioned photos.

Using the quarter-inch bit to drill the numerous air-circulation/root holes.


Bruce shows how to visualize the bottom of the top bucket by holding the set up to a light source. Mark bucket bottom and drill overflow hole about a half-inch down.

Packing the wicking cups (after slitting) with soil-less mix and then pouring water liberally on top to ensure sogginess before tamping down to eliminate air spaces.

Getting the "shower cap" on over Bruce's monster tomato starts was a challenge.

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There are plenty of reasons to grow plants in these kinds of containers. I keep coming back to the fact(s?) that they're easy to use and they work: "more than double the yield of a conventional garden--using less water, less fertilizer and virtually no effort". They're a nice solution to some of the problems posed by challenging growing conditions on rooftops, balconies, and contaminated soil. I'll admit they're not perfect--all that plastic and added fertilizer--but they let you make the most of whatever you've got.

For the class, we used 5 gallon buckets; other small scale options include pop bottles and 18 gallon Rubbermaid™ totes.

You can make these planters out of almost any type of watertight container, that usually means plastic. Some plastics are ok, others you want to stay away from--short version, avoid #3, 6, and #7.

We used 1 cubic foot of Baccto Professional Planting Mix (available at Gethsemane Garden Center, $10 for 2 cubic feet) per planter. It's a mixture (by volume) of 85% sphagnum peat and 15% perlite, with some lime added to stabilize the pH between 5.5-6.5. You can buy other pre-bagged potting mixes as long as they don't have composted/decaying material, like soil, in them.

By introducing organic, decaying matter into the closed environment of the SIP, you allow for the growth of mold and you impede the flow of water from reservoir to plant. We'd encourage you to stick with the peat for the first year so you have something to base any further experiments on.

However........ Peat is a non-renewable resource. Coir is a terrific substitute, you can buy a compressed brick (it'll expand to 2 gallons when you add water) for $2.60 at Brew and Grow. We've found that a mix of 35% coir, 50% peat, and 15% perlite works well. We'd like to hear from anyone who has had good results growing in just coir and perlite.

Here's list of the tomato varieties planted by the group.

Everyone put 1 cup of Espoma Garden Lime (available at Home Depot) in the top 4" of potting mix of each bucket to ward off blossom end rot. That was followed by 2 cups of Espoma 3-4-6 Tomato-tone (from Gethsemane) in a ring on top of the mix in each planter.

These amounts are based, loosely, on the official Earthbox™ Planting Guide.

Thanks to all who attended, including Nance, Erik from Homegrown Evolution, and Martha. Nice job all around.

We're looking forward to another great group on Sat. May 30th, from 1-3 pm. Send us an email greenroofgrowers [at] gmail [dot] com by May 25th to reserve a spot. More details here.