How to Sew Buttonholes on Stretch Knit Fabric

Sewing buttonholes on stretchy knit fabric, such as jersey, ponte, sweater knit, or sweatshirting, can seem a little daunting. Knit fabric can stretch out under the presser foot as you're stitching it, leaving you with a wobbly buttonhole or one that's much bigger than you intended. In other cases, it may get caught under the dense buttonhole stitches or get pushed under the needle plate - yikes!

Never fear - with a few simple tricks, you can sew neat, secure buttonholes on your favourite comfy clothes. The secret is to stabilise the fabric, choose the right sewing machine settings, and practise on a scrap before tackling your garment.

In this tutorial, I'll show you how to sew buttonholes on knit fabric, with a handy video to guide you through the process. If you've already read our tips for sewing one-step (automatic) buttonholes and how to sew four-step (manual) buttonholes, you'll have a head start. Let's get stuck in!

1) Stabilise the fabric with interfacing

When sewing buttonholes on stretch fabric, it's important to stabilise the area first. Knit fabrics stretch, which can cause your buttonholes to distort both during the sewing process and over time with wear, making them difficult to fasten securely.

Interfacing helps prevent this stretching, as well as supporting the fabric as you sew, so your buttonhole stays neat and the fabric doesn't get stuck during stitching.

Choose a fusible (iron-on) interfacing that's a similar weight to your fabric. It shouldn't matter whether it's knit or woven interfacing, as it's only covering a small area.

If the buttonhole area isn't already interfaced, cut a small rectangle of interfacing for each buttonhole. Make it slightly larger than the buttonhole itself.

Lay each piece glue side down against the wrong side of the fabric, checking it's covering the area with the buttonhole markings. Press to fuse using a hot, dry iron, with no steam.

Top tip: Take care not to stretch the knit fabric as you press. Let the iron do the work, lifting and lowering it as needed rather than dragging it across the fabric.

2) Adjust your sewing machine settings

Insert a ballpoint or stretch needle into your sewing machine to avoid puckering or skipped stitches. And lower the presser foot pressure if you haven't already - this will go a long way to preventing stretching.

Some sewing machines have a dedicated stretch buttonhole setting designed for knit fabrics. It's worth checking your manual to see whether yours has this option.

A stretch buttonhole stitch often uses a slightly longer, less dense, zigzag- or crisscross-style stitch that gives the buttonhole a little more flexibility.

Don't worry if your machine doesn't have a dedicated stretch buttonhole setting. You can use a standard buttonhole setting with these adjustments:

• Stitch length: Set the stitch length to around 0.7 as a starting point - try slightly higher (up to 1.0) for thicker fabrics such as sweatshirt fleece, lower (0.5 or 0.6) for finer fabrics such as lightweight jersey.

• Thread tension: Try lowering the tension slightly so the stitches don't pull too much on the stretchy material.

The thickness and stretchiness of your fabric can affect the result, so treat these settings as a starting point rather than a hard-and-fast rule. Test them out (more on that below) and adjust if needed.

3) Test your buttonholes on scrap fabric

I can't over-state the importance of this step! There's nothing more frustrating than sewing a dodgy buttonhole on a nearly finished garment, then having to unpick dozens of tiny stitches. 

Before sewing buttonholes on your precious handmade garment, sew a test (or three) on a scrap of the same project fabric. For an accurate test, make sure you replicate the area you'll be sewing, with the same number of layers and interfacing.

Sew a test buttonhole with the right side of the fabric facing up. Check the stitch density looks good, and that the fabric hasn't stretched out or tunnelled under the stitches. Also check the buttonhole is the correct size for your button (or drawstring).

Tweak the stitch length and tension settings if you need to, and test until you are happy. It's much easier to experiment on a scrap than to unpick a buttonhole from your finished garment!

If your buttonhole is still not feeding through smoothly, try adding another layer of stabiliser. You can buy dedicated tear-away and water-soluble stabiliser that is easy to remove once you've sewn your buttonholes, or try using a piece of tissue paper. Lay it between the needle plate and project while sewing, adding another layer under the presser foot for very tricky fabrics.

4) Sew and open up your buttonholes

Once you're happy with your test buttonholes, it's time to sew them on your garment.

Keep the fabric flat, holding it up if needed so it doesn't hang off your sewing table, and avoid pulling or stretching it as you sew.

When all your buttonholes are stitched, you can apply a little thread sealant (such as Fray Check) before opening the buttonholes.

Open each buttonhole using a seam ripper or buttonhole chisel.

And that's it! Your buttonholes are ready for buttons.

Alternatives to sewing buttonholes

Not all fabrics are created equal - and that's particularly true when it comes to stretchy knit fabrics! If you've followed all these tips and your fabric is still not playing ball, don't give up on your project completely.

If you need an alternative fastening, try hand-sewing snap fastenings onto the opening, or adding cute ties.

Watch the video below to see how to sew buttonholes on knit fabric, demonstrating on the snuggly Stella hoodie pattern from Tilly's book Stretch:

Ready to sew something cosy?

Have a go using this technique on the Cece joggers, Erin dungarees, or the Stella hoodie from Tilly's book Stretch.