How to Sew a Picnic Blanket That’s Water-Resistant

I love picnicking and having your own picnic gear enables you to grab it and go without much planning whenever the mood strikes you (and the weather cooperates!). I insist on having a quality picnic blanket, so I can sprawl out, read and maybe even take a nap! However, I really don’t like the dampness that can make blankets wet under your body while trying to lounge. Sure, you could take something thicker to delay the process, but that can be heavy and cumbersome to carry to the park.

The best option? Sew your own blanket with a water-resistant backing! This will protect you from any ground moisture (sprinklers, dew, pets) and ensure an afternoon of easy relaxation!

Follow along with these steps to create your own waterproof blanket, perfect for your next trip to the park!

how to sew a picnic blanket

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gather your tools

Step 1: Gather your tools.

The key to this blanket is the backing fabric. I suggest using laminated cotton, which is regular cotton fabric that has been laminated with a lightweight plastic coating that will prove to be water-resistant (though keep in mind it isn’t waterproof).

  • 2 yards of laminated cotton fabric for the bottom layer
  • 2 yards of cotton fabric for the top layer
  • 8 yards of double folded bias tape
  • Clear ruler
  • Water soluble marking tool
  • Thread
  • Scissors
  • Traceable curve (could be a bowl or anything else to help you draw a curve)
  • Binder clips
  • Pins

mark edges

Step 2: Cut the fabric.

Fold the fabric with the selvages together and all the raw cut ends together on one end. Use a ruler and water soluble marking tool to draw a straight line at the cut ends. When your fabric is cut at the store, it’s almost never straight, so we want to clean it up.

Note: I am doing the following steps with the wrong side of the fabric up, so the lamination is face to face and the cotton side is up, making it easier to mark on with the fabric.

trim edges


Following the line you just drew, carefully cut through all four layers at the end of the fabric, so the cut ends are nice and straight. For these steps, resist pinning the layers together, as that will puncture the lamination.

trim selvage


Trim off the selvage edges along the side of the fabric as well, through all four layers. Again, do not pin. Use pattern weights or place some books on the fabric to keep it in place while cutting to hold things together.

cut curved corners


Place a curve, bowl, or anything round on the corner of the fabric. Line up the outside edges of the fabric and the curve so the line is continuous. Use your water-soluble marking tool to draw the curve, then cut it out with scissors through all four of the layers.

cut fabric to match


Fold the fabric in the same way as the laminated cotton. Lay the laminated cotton layer on top of the fabric — the folded edges should be together, cut edges together and selvage sides together. Trim the fabric to match the size of the laminated cotton.

layer fabrics

 Step 3: Assemble the layers.

Place the laminated cotton down with the lamination on the bottom and the fabric up. Place the fabric on top with the wrong side down so the layers are wrong sides facing.

clip together


Line up the edges and secure round the entire blanket with binder clips. You can pin this if you prefer, just remain near the edge so the puncture holes will land in the seam allowance.

cat interference


If you do all of this on the floor as I did, beware that this is a big pet magnet!

sew edges


Step 4: Sew the layers.

I used my serger machine to sew the layers together for a quick and sturdy finish. If you have a serger machine, you can sew this together on a 3/8″ seam allowance. If you are sewing this on a regular machine, sew at the 3/8″ seam allowance with a straight stitch, then trim down to 1/8″ after sewing. Be sure to use a needle 80/12 or 90/14 in size to accommodate for the thickness of the lamination.

press bias tape

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Step 5: Bind the edges.

If you are using store bought bias tape, the ends will need to be joined to form a strip long enough to go all the way around the perimeter of the blanket. Open up one end of the bias binding and press the first 2″ flat with an iron. Repeat with the end of the next section to join.

trim bias edges


Trim the two ends to a 90-degree angle, as most packaged bias binding comes with jagged edges at the ends.

mark bias stitch line


Place the bindings right sides facing, forming a 90-degree turn. Pin together and draw a line from the top left corner to the lower right corner. If using store bought binding, note that one side of the binding is slightly shorter than the other side. When stitching the ends together, keep the sides even so the short sides will end up on the same side after sewing.

sew bias seam


Follow the line and stitch the two layers together. Trim the seam allowance to 1/4″ and press the seam allowance open. Repress the folds in the binding so it is one long continuous strip.

pin binding to edge


Place the binding over the edge of the fabric with the shorter side of the bias tape on top of the fabric side. This is the side that will be facing you during the sewing process next. Sandwich the fabric into the middle fold of the binding. Pin in place.

stitch binding


Stitch close to the outside fold with a straight stitch. With the shorter side on top, you should easily catch the binding on the underside at the same time to close the edges up.

binding curve


When you reach the corners, carefully form the binding into the curve and stitch around the edges. Turn the stitch length down if necessary.

your finished picnic blanket


Just prior to the end of the binding, fold the end under and stitch in place to end. And that’s it! Place the laminated cotton side down on the ground and lay on the upper fabric layer with the peace of mind that you’re not resting your body in dog pee or other park moisture!

Wipe off after picnicking, fold, and go!

What are your picnic must-haves? I’d love to hear your recipe for the perfect picnic!

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