I went through making the SIP at http://figs4funforum.websitetoolbox.com/post/kiddy-pool-sip-6838413?pid=1282691897#post1282691897 I'm in the process of up potting so I thought I give an update on what I've learned.
First off, I used one inch strips of Pellon Thermolam TP970 as wicks. I split them in half where they went through the bag and spread them to disperse the water. You can see the end of one strip in the second picture up at about the level that the roots were at when I up potted from cups. These weren't enough. I had to water from the top to keep the bags from drying out, and fill the reservoir till the water was touching the bottom of the bag to keep them wet enough (although, I did let the level drop between watering's). That contact with the bottom of the bag inspired the roots to come through the bag without air pruning, as you can see from the first picture.
On the plus side, the SIP did buffer the plant from drying out quite a bit. I watered well before leaving for four dry sunny days. When I got back the reservoir was dry but the figs weren't wilting. So it does work, just not as well as I'd like.
Looking inside the bag you can see that the roots didn't air prune as well as hoped. They didn't circle but they did turn and run down. They did root prune enough to form a pretty good root ball that held the soil mix together.
This was a MBVS. Those and Hardy Chicago were pretty much the same. VdB showed much less root growth during the same period. They weren't coming through the bag and the root ball looked a lot more like what I wanted.
This is the up potting in progress with the first SIP with the small bags in the back and the the one with the up potted plant in the front. The one in-between has peppers in Walmart bags I'm doing away with the wick. I'll top water till there's a little standing in the bottom then let them dry a bit before re-watering. I left the 50/50 perlite/compost mix in the root ball and planted them in a much denser mix (66% potting soil 16.5% composted manure 16.5% perlite). This will let the water go down through the roots and out to the dirt. I'm hoping that it will encourage the roots to stay dense to catch the water rather than spreading to search for it. Late in the summer I hope to up pot them to Walmart bags. Those are more durable and have handles which should help in moving them into winter quarters. If the roots aren't developed enough for up potting I may just put them, bag and all, into 5 gal. buckets to move them.
I have more cuttings coming from kind and generous forum members. Since I have the set up I will probably try this again but I'll at least double the size of the wicks and extend them much higher in the bags. I'll top water if I have to but I want to keep the bottom of the bag out of the water and see if I can get the air pruning to work. I may have to change fabrics.
To stray from the topic a little here are some pink oyster mushrooms I'm growing in bags of straw.
