By provisional I mean a cast on that is not permanent--it can be pulled out leaving live stitches which can be worked in the other direction. This comes in handy in all sorts of situations:
- Not sure what sort of hem or edge you want to do? Ribbing? Corrugated ribbing? Garter stitch hem? Provisionally cast on (PCO) and start knitting. When you're ready, go back and finish off the hem.
- For a lace scarf or table runner, PCO at the middle and knit each side out so both ends match.
- For a sock knit top down, skip the ribbing; PCO for the leg, knit down, then go back and knit the hem bottom up and finish with a tubular CO or Jeny's Surprisingly Stretchy Bind Off.
- For a sweater knit bottom up, PCO in the middle of the body (or sleeve). Later, go back and knit down to wanted length. No more too-short sweater bodies or sleeves! (Credit for this gem of information goes to master knitter Amy Detjen. I still remember the day she mentioned it: a light bulb went off for me.)
Here's how I learned to do a PCCO:
1. Use a waste yarn of similar weight but contrasting in color to the yarn you will be knitting.
2. Leaving a short tail, with the waste yarn create a slip knot and slide the knot onto a crochet hook.
3. Hold the crochet hook in your right hand with hook pointing away from you. Hold the waste yarn in your left hand. (Reverse positions if left-handed.)
4. Place a needle on top of the waste yarn, parallel to and left of the crochet hook; this is the starting position:
5. *Reach the crochet hook over on top of the dpn, grab the waste yarn (swiping down/toward you), and pull it through the loop on the hook:
6. Return the needle and crochet hook to their starting positions*:
7. Repeat steps 5 & 6 until you have created the number of stitches you need on the needle.
8. Note the open stitches created along the bottom of the needle:
Aside: These open stiches are created when swiping down/toward you for each chain. In every book or place I've seen how to do a PCCO, it's always stressed to make sure these stitches along the bottom of the needle are open. In one of my classes recently a student naturally swiped up/away from her for each chain, which left twisted stitches along the bottom of the needle. We experimented and found that chains/stitches created that way still pulled apart freely from the knitting, although when undoing the CO, it was noticeable that each PCCO stitch was twisted. Whichever way you swing, I'd just recommend being consistent.
9. To end, chain several loops off the dpn and then pull the waste yarn tail through the final chain. These loops serve an important purpose: they will help you remember which end to pull on when you go to pull out the waste yarn.
When you are ready to remove the PCCO, starting at the end with extra loops, slowly and carefully remove the PCCO, placing the live stitches onto a needle as you go. I like to go stitch by stitch.
A few tips when using the PCCO:
- use a waste yarn of a color in stark contrast to your main yarn (and of similar weight)
- cast on extra stitches and then, upon counting, drop off what isn't needed
- always knit the first row or round in plain knitting (no fancy colorwork yet)
- when removing a PCCO, remove it stitch by stitch, placing each live stitch onto a needle as you go (as opposed to going WHEE! and ripping it out willy-nilly)
- if you find the stitches tight when removing the waste yarn, PCCO onto a needle size or two larger than that with which you will be knitting (or, if you've already begun knitting, place the live stitches onto a temporary needle of smaller size until you are ready to work the stitches)
- if knitting flat, there will be one less provisional stitch than main stitches; if knitting in the round, this is not an issue: there will be one provisional stitch per main stitch. If you are a stitch short, just M1.
For more information, Lucy Neatby has a good description of the PCCO in her wonderfully technical book Cool Socks, Warm Feet (2003), Tradewind Knitwear Designs, Inc. She also has a good video demo on YouTube.
**Another provisional cast on is the invisible cast on, which I like to call twisty-wrap. It is set up as a long-tail cast on with the waste yarn held in front and the working yarn held in back. There are good descriptions & diagrams of it in Meg Swansen's & Elizabeth Zimmermann's books, including Meg Swansen's Knitting (1999), Interweave Press. This book of Meg's has a wonderful technique section. This method is also commonly printed in the glossary of "Interweave Knits."