One of the best things I learned to do as a quiltmaker is how to make pieced borders fit accurately and easily on my quilts. I learned this from Sue Garman, when I made her Washington Medallion quilt in 2009. It is a great gift for me to know how to do this and I use this technique often in my work.
I will use Rajah Revisited to describe the way this works. This quilt is the 2016 Block of the Month pattern from www.thequiltshow.com It is a smaller version of a quilt made in 1841 by women prisoners being taken by ship from England to Australia.
Here is the basic idea: The instructions for month 3 took us through the appliqued border--the light tan border with appliques on it. Instructions for month 4 had us make the squares on point border and join those to the middle, with a very narrow "floater" border. Those 2" finished green squares with cheddar triangles around each square were paper-pieced, easy and accurate.
To ensure your pieced borders will fit precisely to the middle of your quilt, you piece those borders FIRST, before calculating what size the "floater" or "spacer" border has to be--this is the narrow medium blue border here. We will do some simple math to determine what size that narrow border has to be to precisely fill the space between the middle part and those pieced borders.
1. Length of Pieced Borders: 26.5" (2" squares x 13 = 26" + .5" seam allowance)
2. Length of Quilt Center" 25" including seam allowances
3. Subtract 2 from 1: 1.5"
4. Divide the result in half: .75" This is the width the floaters need to be, finished size. Add .5" seam allowance.
So, my blue borders were cut 1.25" x 25". two of those for the left and right sides AND 1.25" x 26.5", two of those for the top and bottom edges. I sewed on the left and right blue borders and pressed toward the narrow blue border. Then I sewed on the top and bottom blue borders and again pressed toward the narrow blue border. All that was left to do was add the pieced left and right borders to each side then add the top and bottom pieced borders, adding a corner square to each side of those borders. Everything fit like a glove.
NOTE: Because this quilt is square, I only have to do one set of measurements. With a rectangular quilt, you do two sets of measurements, the left/right borders and the top/bottom borders.
I was lucky because my pieced borders turned out the correct size--after I made a few "adjustments". After piecing the first 13 squares together and pressing the seams open, it measured 26.75", one-quarter inch too large. I looked at each seam to find two that were a little bit narrow and tightened them up--and just like magic, the border became 26.5" as it should have been. For the remaining 3 pieced borders I paid more attention and checked the seams as I went to be sure they were accurate--no more "snugging" necessary.
If all of your borders turn out 26.75" you can still make this work just fine. Let's try:
1. Length of Pieced Borders: 26.75"
2. Length of Quilt Center: 25"
3. Subtract 2 from 1: 1.75"
4. Divide the result in half: 7/8" Width each floater needs to be, finished. Add .5" seam allowance so you cut the floaters 1 3/8". Your ruler has a 3/8 measurement, just use it. Now your slightly too large pieced borders will fit your center perfectly, no tugging or squishing necessary.
Here is Joyful Journey, my version of Sue's Washington Medallion--as you can see, there are many floater borders and each one was calculated in this manner so the next pieced border would fit the growing center of the quilt perfectly. This quilt was juried into AQS Paducah 2010 and appears in the book 500 Traditional Quilts. It was included in the special exhibit from that book at International Quilt Festival Houston 2014 and Chicago 2015 and Portland 2015.
Now you know how to make pieced borders fit precisely. Remember, there are only three things you can do wrong in piecing a quilt top: the cutting, the sewing, and the pressing. Take your time, measure as you go, and press firmly.