Shoofly Quilt Block: Easy Nine-Patch with Triangle Corners

Shoofly block: green center, green triangles in the outer corners and cream side squares — Print in the center and in the outer half of each corner; background on the sides.

Nobody knows for certain where the name comes from. Fons & Porter's Quilting Daily calls the origin speculative and mentions a plant once said to drive off flies, and notes that "Hole in the Barn Door" was another name for the block popular with farmers in the mid- to late 1800s. You'll find it spelled shoofly and shoo fly; they're the same block.

How the block is built

Shoofly block pulled apart into four corner triangle squares, four cream side squares and a green center — HST, background, HST / background, print, background / HST, background, HST.

A 3 × 3 grid. In each corner HST, the print triangle sits in the block's outer corner and the background half faces the center. With the print center, the print forms an X across the block. Turn the HSTs the other way, print toward the center, and you get a different look: a ring of print with background corners. Both are correct blocks; just keep all four corners the same in any one block.

Cutting chart (one block)

Finished block	Unit	HST squares (2 background, 2 print)	Background side squares	Print center
6 in	2 in	3 in	4 squares 2½ in	1 square 2½ in
9 in	3 in	4 in	4 squares 3½ in	1 square 3½ in
12 in	4 in	5 in	4 squares 4½ in	1 square 4½ in

The HST squares include extra for trimming; cut them at 2⅞, 3⅞ or 4⅞ inches if you prefer not to trim. Unfinished block: 6½, 9½ or 12½ inches. Checked by calculation.

A charm square (5 inches) is big enough for the HST squares and center of a 12-inch block; that's a quick way to make a scrappy set from one charm pack and a background fabric.

Choosing fabrics

The shoofly depends on contrast between the print and the background more than on the prints themselves. Lay the two fabrics side by side and take a black-and-white photo with your phone: if they turn into the same gray, the X will disappear. A medium or dark print on a light background is the safe choice. Busy, large-scale prints get chopped up in 3-inch units, so save those for the plain alternate blocks, where the whole print shows.

Two colors are traditional, but the block takes a third easily: make the center square a different fabric from the corners, and the X turns into four corner triangles around a contrasting middle. In red and blue on cream it becomes a patriotic block for a Fourth of July table runner or a lap quilt for a veteran.

Other sizes

Any finished size divisible by 3 works. Divide the block by 3 to get the unit, then cut the side squares and center at the unit plus ½ inch and the HST squares at the unit plus 1 inch (or plus ⅞ inch for exact). A 15-inch block, for example, has 5-inch units: 5½-inch squares and 6-inch HST squares. For a 10-inch block the unit is 3⅓ inches, which no ruler marks cleanly, so pick a size divisible by 3 instead.

Piecing steps

Pair each background HST square with a print square, right sides together. Draw a diagonal on the wrong side of the background square.
Sew ¼ inch from the line on both sides. Cut on the line.
Press toward the print. Trim the four HSTs to 2½, 3½ or 4½ inches with the seam running exactly corner to corner.
Lay out the block. Top row: HST, background square, HST. Middle row: background, print center, background. Bottom row: HST, background, HST. Turn each HST so its print triangle is in the outer corner of the block.
Sew the top and bottom rows and press toward the HSTs. Sew the middle row and press toward the center square. The seams nest when you join the rows.
Join the rows. Press the two long seams toward the middle row, or open.
Measure: the block should be ½ inch larger than its finished size.

Making a dozen or more? Cut from strips: a 4-inch strip across the width of the fabric gives ten 4-inch HST squares, and a 3½-inch strip gives eleven 3½-inch squares (counting on 40 usable inches). Chain-piece all the HST pairs at once, then all the rows, and keep each block's units in a stack so the prints stay together.

Common mistakes and fixes

Problem	Cause	Fix
One corner looks different	An HST turned with print toward the center	Check all four corners before joining rows
Corner point cut off at the block edge	HST seam off the corner after trimming	Trim with the 45-degree line on the seam
Seams won't nest	Rows pressed the same direction	Outer rows toward the HSTs, middle row toward the center
Block too small	Seam allowance wider than ¼ inch	Test your seam; see how to sew a quarter-inch seam

Quilts made from shoofly blocks

Shoofly quilt: 18 shoofly blocks alternating with 17 plain squares, 5 across and 7 down, with a red border — Eighteen 9-inch shoofly blocks alternating with seventeen plain 9½-inch squares, 5 across and 7 down, with a 3-inch border: 51 × 69 inches.

Alternating shooflies with plain squares spaces the blocks out and halves the piecing. The plain squares are where the quilting shows, so put a simple feather in them, or stitch a name and date into one. Use a different print in each shoofly, as in the diagram, and you have a scrap quilt held together by a calm cream background.

Set side by side without plain blocks, the outer triangles of neighboring blocks meet and form larger print squares on point where four corners come together, a secondary pattern that's easy to miss until the blocks are sewn. For a quilt in this size range with a full cutting chart, our nine-patch throw uses the same alternating layout with plain nine-patches, and you can swap in shooflies of the same 9-inch size.

Related blocks: the churn dash uses the same corners with two-strip bars on the sides, and the friendship star moves the triangles to the side positions.

Shoofly quilt block