Rubberband FAIL ... in 21 Days

Just 21 days after our test using Big Rubberbands to secure the shower caps on our SIPs, we had a failure.

Don't try this at home.

The rubberband broke yesterday. It feels crumbly to the touch, like a rubberband that's been sitting in a drawer for 10 years. Just three weeks in a little hot sun and some cold weather.

Live and learn. I'll start using garden twine to hold the plastic in place.

....

Updated 4.18.10 -

We got an email from one of our readers, David.

I use punctured 700c inner tubes for bicycles. First I cut on either side of the stem (air valve) then fold the tire in half and cut it in two. I then use a square knot to fasten the tube around the bucket. Bicycle Shops just throw the inner tubes away so just ask your local shop if they could save you some.

Sincerely,
David

Thanks David!

Sub-Irrigated Chicago Rooftop Garden: New Approaches for 2010

We're making a few changes this year, large and small, to speed multiple SIP planting and help preserve diminishing peat bogs.

Using a large rubber band to secure the 5-gal SIP shower cap
Sounds obvious, but in the past we've used string or the more expensive zip ties. We'll see if rubber bands hold up under all that UV, though the position of these under the bucket lip should mean the sun won't bake them to smithereens. You need nimble fingers to use them, though.

(And kudos to the marketing person who named these rubber bands.)




Potting Mix: peat+perlite vs. coir+perlite

We want to move away from peat moss, which develops over millenia and, when harvested, releases massive amounts of carbon dioxide into the atmosphere.

We're going to make this experiment as exacting as possible, planting two peppers, two tomatoes, and two sets of greens side-by-side, one each in coir/perlite and the other in our old peat/perlite mix (of undetermined exact specifications).

Bruce's recipe is: 70% (by reconstituted volume) coir and 30% perlite.

We found a relatively inexpensive (including shipping) source for large blocks of coir at Rolanka. We've been buying the 5:1 compressed blocks. Four come bundled together, costing $58 delivered to Chicago. Each of the blocks, reconstituted with 6 gallons of water and combined with 3 gallons of perlite (from Anton's Nursery in Evanston, $20 for a 4 cubic foot/30 gallon bag or at Home Depot for $2/gallon), makes enough potting mix to fill three 5-gallon bucket planters (3 cubic feet of mix).

All those numbers can be summed up in one sentence: The coir/perlite mix is $5.50/cubic foot, about the same price as the peat based potting mix we've been using.


Cutting out exact-sized plastic rounds for the "shower caps"
Sounds minor, but I formerly used an old form to score garbage bags and cut out shower cap circles. They were a little large and I always ended up trimming the extra skirt from the top of my SIPs. And yes the results looked raggedy.

I discovered the 16" diameter recycled Olive Garden salad bowl (garbage picking at that graduation party last year was a boon) creates a perfectly sized round for the 5-gal bucket SIP. You can cut a plastic circle out of anything waterproof--a soil bag, whatever. I like garbage bags because they're thin and flexible.





Water fill tubes
One of our local readers last year brought us a roll of polyethylene drip irrigation tubing, which we'll cut and use for fill tubes on the new SIP run this year. Generous person whose name we have misplaced: thank you!

We'll keep you updated on the results of our changes. If you're making any, let us know.