Alternating up and down stitch is an easy variety of Up and Down buttonhole stitch. This stitch can be used in freeform organic way. In the sample below I have used Alternating up and Down stitch worked in cotton perle thread before adding Raised Cross Stitch Flowers and long bugle beads. This sample is from a hussif I made that you can see here.
How to work Alternating Up and Down Buttonhole Stitch
Work Alternating Up and Down Buttonhole stitch from left to right and be familiar with the regular form of Up and Down Buttonhole stitch. 
Starting as you would with buttonhole stitch, and with your needle pointing downwards, wrap the thread under the needle and pull the needle through. 
For the second part of the stitch, insert the needle and take a bite of the fabric so that the tip of the needle is pointing upwards, as illustrated. 
Wrap the working thread under the needle and pull the needle through the foundation fabric. As you pull the needle through, pull the needle towards you instead of away from you. As you do this hold down the loop that forms with the left thumb to prevent it slipping. This loop forms the bar at the base of both stitches. For regular up and down buttonhole, you would work along the line at this point.
Note: I have noticed online that some instructions create a loop then lace the working thread through the stitch. This is, let’s say, a creative way of doing it and is technically incorrect, as the loop is created as you stitch and once you have the rhythm of the stitch, it is easy and quick to do.
Now, the Alternating part…
For Alternating Up and down buttonhole stitch, you work the next pair of stitches pointing in the other direction.
Once again, make a regular buttonhole stitch, but this time point your needle upwards wrap the thread under the needle and pull the needle through. For the second part of the stitch, insert the needle and take a bite of the fabric so that the tip of the needle is pointing downwards, as illustrated. As you pull the needle through, pull the needle away from you and hold down the loop that forms with your left thumb to prevent it slipping.
This forms the second pair of stitches. Continue along the line with alternating the direction of each pair of stitches as illustrated.
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Thanks for making me learn new stitches. My samples are here.
http://hobbysewing.blogspot.com/2020/09/tast-32-beyond-tast-32.html
This time I managed to tame the stitches on a curve!
http://queeniepatch.blogspot.se/2014/09/tast-127-beaded-alternating-up-and-down.html
Hi Sharon,
Hope you are enjoying the weekend. I have started beaded alternating up and down buttonhole stitch samples here-
https://jizee6687.wordpress.com/category/tast-2014/33-127-beaded-altupdown-buttonholestitch/
Thank you,
Chitra
Hi Chitra I took look at your stitch samples I really like the way you are using them!
My attempts: http://210920746822434353.weebly.com/my-stitchery-journal/2014-staying-connected-week-thirty-four
Hi Sharon,
As an experiment,alternating up and down buttonhole stitches were worked on some shapes and curves on my sampler.
http://jizee6687.wordpress.com/2014/08/25/tast-2014-32-126-alternating-up-and-down-buttonhole-stitch/
Thank you,
Chitra
Oh, I like this stitch! #126 is done:
http://queeniepatch.blogspot.se/2014/08/tast-126-alternating-up-and-down.html
I have finished samples for Nos. 126 and 127. It is a great pair of stitches to do and I intend using them more often.
https://crazyqstitcher.wordpress.com/
Thanks again Sharon for taking time for us when you have such a busy year happening.
Hi Sharon,
Here is stitch 125 beaded herringbone, very plain but it makes a nice band.
http://carorose.typepad.com/my_weblog/2014/08/tast-2014-stitch-no-122.html
Have a good week.
Carolyn
I am looking forward to trying the beaded version! In the meantime you can see what I did at http://princessbubblescreates.blogspot.ca/2014/08/take-stitch-tuesday-alternating-up-and.html
Thank you for sharing! I already have ideas for ways to use these two stitches!
This week I tried out the whipped wheel and the beaded herringbone stitches.
http://monkeyandmutt.blogspot.com/2014/08/tast-08192014.html
Almost up to date. Here are samples 122, 123 and 125.
http://linsartyblobs.blogspot.co.uk/2014/08/tast-122-123-125.html
Today I wrote about the closed herringbone. I used it for shadow work, there are a few links with more info about shadow work in my blog post:
http://fat-quarter.blogspot.nl/2014/08/closed-herringbone-or-double-backstitch.html
Thank you so much for youre generosity!!!!!!!!