I have not seen any other pictures of roots at transplanting time in this thread.

FMD,

I was also wondering why none of the instructions mention putting holes for better air flow in the rooting section of the SIPs. It seems that it would be a good idea as long as the wicking system took this in to account. Has anyone here done it?

Yes, that is what I do. Lots of holes in the little upside down cup.

2 Liter fabric wicked Soda Bottle Sip Update...
 
3 weeks root growth in a 2-2-1 Coir-Peat-Perlite mix, with healthy looking roots. Watered once with 6 oz of water. The darker lower portion of mix indicates that it doesn't need watering. The surface is also dry, and there is no evidence of Fungus Gnats, even though it is being kept (purposely) next to a 5 gallon Limequat that is infested with fungus Gnats.

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Rewton,
You're welcome.

I have found that the fabric wick is not absolutely necessary, it will be included in all my SIPs because it distributes the water evenly through out the mix, eliminating the waterlogged container/wick bottom and can be used to wick water out of the planter.
If you drill 3 or 4 holes 1/4" diameter in the bottle cap and screw it back in place, the "soil" wick will perform quite well, I have two 2 liter SIPs with soil wicks under test and they are wicking properly, It just takes longer to wet all the soil in the planter when watered.

Thanks for posting this Pete.  I have my wicking material on order and will give this a try once it arrives.

I am a little confused about how the 2-liter SIPs are supposed to drain. Maybe I missed this but on other instructions I see a drain hole is drilled and a straw inserted so the water cannot get above a certain level. If I were to drill an overflow hole would it be below the holes drilled in the inverted top of the bottle, or is the water supposed to wick up through the holes?

I don't think you need an overflow hole, if you are filling the reservior by hand.  The overflow hole in the large SIPs is so you can know when you have filled the reservior, or to drain out excess water in an outdoor situation in the rain.
If you lift up the top part of the 2L soda bottle SIP, you can just add the 1 inch or 2 of water that you determine adequately waters the container, then replace top part.  The fabric wick pulls the water up into the top part.

So the holes are supposed to remain above the water level, correct?

I think so, at least that is how mine are placed  :)
This is new to me too.  I have a dozen of these going so far, more to do in the next week or so.

Milehighgirl,
The holes are for aeration, they are the bottom of the aeration platform and are above the reservoir level whenever its filled.
   
Ed's explanation for the lack of drainage holes is correct. The 2 liter SIPs were designed for indoor use, if you are placing them out in the weather, you could drill a hole at about 1-1/2" up from the bottom of the reservoir.

For growing fig cuttings the reservoir is only "filled" when the soil is dry and needs to be watered. By figuring out the "Reservoir Maximum Fill" amount, you never need to worry about overwatering. For my test 2 liter SIPS with 5 cups of mix, the maximum fill amount was 6 oz. Every mix batch will be different, but can be easily found. This same procedure can also be used with non SIP planters. Good Luck.

ascpete,

Thanks for the explanation. I think I was confused with FMD's method, but since the styrofoam is opaque the hole is necessary.

Here's my latest variation, based on a different wicking system discussed in this and other threads.

I like this one because it eliminates the straw and overflow hole and because it is modular.

Is there a way to measure if my mini-SIP design is wicking too much moisture? I am using a nespresso cup (to act as a wick/net cup) in a 18oz SOLO cup set in a 16oz cup for a water reservoir. The bottom of the nespresso cup/wick is packed with potting mix and pretty much sits in the bottom, so 1/4-inch of water. How do I know if the mix is too wet? For those who don't know the size of a nespresso cup is approx the size of a soda bottlecap

Since I am very forgetful I know SIPs are probably my only chance of rooting twigs. I am also worried about how long it'll take to do this trial run and am itching to just put them in SIPs...

The amount of water pulled up into the mix is a function of the mix itself and the characteristics of the wick.  What you might do is to put mix in your cup that has the desired amount of moisture and weigh it.  The set up your SIP and let it equilibrate for a few days (without a cutting) then weigh the cup to see if too much water has been  aborbed into the mix or not enough. This will give you an idea of how your system is working.

I'm glad this thread got bumped because I plan on building one of these SIP's today for my cuttings. Great ideas in this thread and I have nice scale I use for my Wine Making so that will come in handy.