Siren Side-Slit Dress – Crochet Pattern (from my book: Summer Crochet)

Hi all!

This post includes everything you need to know about the Siren Side-Slit Dress (the cover design!), a size-inclusive crochet pattern for a figure-hugging beach dress, featuring an enchanting mermaid-like stitch pattern and a high leg slit for ease of collecting seashells along the shoreline. This stretchy dress will have you feeling cute, covered, and comfortable!

The Siren Side-Slit Dress is available as an independent PDF (Ravelry, Etsy, and other links included below) and is an original design from my new book Summer Crochet: 19 Delicate Designs with Simple Lace and Timeless Silhouettes, released in spring 2025. This book includes 19 size-inclusive, warm-weather garment and accessory patterns using a variety of techniques and construction methods to ensure there is something of value for every skill level. Each pattern is written with an inclusive size range from XS to 5XL and each size has been thoroughly tested, thoroughly tech edited, and fully charted! We had hundreds of crochet pattern testers for this book to make sure that each size fits its intended wearer in a way that makes them feel beautiful.

You can buy this book with confidence, knowing that each pattern was written for you and your unique body measurements.

Some Quick Links Before You Begin:

Find the PDF version on Ravelry, Etsy, and my website.
Add your finished project and view other completed projects on Ravelry here!
Use the pattern hashtag #SirenSideSlitDress on Instagram to show off your makes! Be sure to check out the book hashtag, #SummerCrochetBook, too!
Shop Lion Brand 24/7 Cotton DK from Lion Brand here!
- Be sure to scroll down to see other great yarn substitutes!
- The full Lion Brand crochet kit will be available here in early May! (comes with all yarn required for your chosen size + a FREE copy of the PDF pattern)!
For any questions about this pattern, please email knitsnknotswpg@gmail.com and I’ll get back to you asap!

Where Can I Find the Physical Book?

(Both physical and e-book versions are available!)

Shop Summer Crochet on Amazon (US) here.
Shop Summer Crochet on Barnes And Noble here.
Shop Summer Crochet at Chapters (CA) here.
Shop Summer Crochet on Amazon (CA) here.
Shop Summer Crochet on Amazon (UK) here.
Shop Summer Crochet on Indie Bound here.
Shop Summer Crochet on Blackwell’s here.
Shop Summer Crochet on Books-A-Million here.
Shop Summer Crochet on Books Inc. here.
Shop even more platforms here.

Order my first book – Modern Crochet Sweaters: 20 Chic Designs for Everyday Wear – here!

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This post contains affiliate links. This means, should you make a purchase, I will receive a small portion of the sale at no extra cost to you. All opinions are my own. View my Privacy + Disclosures Policy here.

About

Meet your new favorite swimsuit topper! The Siren Side-Slit Dress is a figure-hugging beach dress designed for day trips to the ocean. Featuring an enchanting mermaid-like stitch pattern and a high leg slit for ease of collecting seashells along the shoreline, this stretchy dress will have you feeling cute, covered and comfortable.

This pattern is fully written + charted.

Materials

Yarn: DK—Lion Brand 24/7 Cotton DK in colorway “Cream”

100% cotton
273 yds (250 m) per 3.5 oz (100 g) skein
Find this yarn on lionbrand .com or yarnsub.com to find comparable substitutes available in your region.

Yardage Required: 4 (4, 4, 4, 5) (5, 6, 6, 6) skeins or approximately 850 (900, 975, 1050, 1175) (1225, 1375, 1475, 1550) yds (777 [823, 892, 960, 1074] [1120, 1257, 1349, 1417] m)

Yarn Substitution: Scroll down for an extensive list of yarn substitutes and yarns used during pattern testing.

Hook: Size U.S. E/4 (3.5 mm) or size needed to obtain gauge

Notions: Tapestry needle, 3 locking stitch markers, several more stitch markers (optional) to help with seaming

Yarn Substitution

Lion Brand 24/7 Cotton DK has the following properties:

100% cotton
273 yds (250 m) per 3.5 oz (100 g) skein

Substitute Lion Brand 24/7 Cotton DK with any similar light DK-weight (category #3) yarn that matches gauge. Most fibers should work fine in this project, particularly cotton or cotton blends. Avoid 100% bamboo yarns, as these will be too slippery; a little grip is needed. Note that DK weight is sometimes referred to as “8-ply” in Australia.

Appropriate Yarn Substitutes:

This list below includes some yarns I added myself in addition to the yarns used and recommended by testers.

As a reminder, you will need approximately 850 (900, 975, 1050, 1175) (1225, 1375, 1475, 1550) yds / 777 (823, 892, 960, 1074) (1120, 1257, 1349, 1417) m of DK weight yarn.

The following DK weight yarns should work well in your project!

- Cascade Yarns Hampton (70% Cotton, 30% Linen)
- Cloudborn Pima Cotton DK (100% Cotton)
- DMC Happy Cotton (100% Cotton)
- GRÜNDL Cotton Fun (100% Cotton)
- Hobbii Rainbow Cotton 8/6 (100% Cotton)
- K+C Essential Cotton (100% Cotton)
- Katia Linen (53% Cotton, 47% Linen)
- Lammy Yarns Rio (100% Cotton)
- Lion Brand Coboo (51% Cotton, 49% Rayon from Bamboo)
- Lion Brand Cotton Jeans (100% Cotton)
- Lion Brand Truboo (100% Rayon)
- Paintbox Yarns Cotton DK (100% Cotton)
- Premier Cotton Sprout DK (100% Cotton)
- Rico Design Essentials Cotton DK (100% Cotton)
- Rowan Mode Cotton DK (100% Cotton)
- Sirdar Happy Cotton DK (100% Cotton)
- WeCrochet CotLin DK (70% Tanguis cotton, 30% Linen)

Gauge

Gauge for a stretchy stitch pattern like this can be difficult to measure. Since this stitch pattern is extremely stretchy, there is a lot of forgiveness in the fabric. Try your best to get as close as you can to the measurements given.

For Swatch

Ch 48.

Work Rows 1–4 from Back Panel, then rep Rows 3 and 4 (finishing with a Row 4 rep) until you have worked a total of 8 rows. Your completed swatch will have a total of 4 Shell rows worked with 4 Shells within each row.

For this project, gently block your swatch without stretching it too aggressively. This blocking process is intended to smooth out the stitches and create a neater fabric, as opposed to stretching it to its maximum dimensions. When you wear your dress, the fabric will contour to your measurements—stretching taut over your curves and fitted around your waist.

Your blocked swatch should measure approximately 10 inches (25 cm) in width and 3 inches (8 cm) in height in order to achieve the finished measurements listed in the sizing chart.

For reference, my swatch pre-blocking measured approximately 9.25 inches (23 cm) across and 3 inches (8 cm) in height.

Sizing + Finished Measurements

The following chart is a screenshot from the PDF pattern.

Terms + Abbreviations Used

Written in U.S. Crochet Terms

BOR: beginning of round
ch(s): chain(s)
ch-sp(s): chain space(s)
dc: double crochet (tr in U.K. terms)
PM: place marker
rep: repeat
rnd(s): round(s)
RS: right side
sc: single crochet (dc in U.K. terms)
scBLO: single crochet through the back loop only (dcBLO in U.K. terms)
sc2togBLO: single crochet 2 stitches together through the back loops only (dc2togBLO in U.K. terms)
sk: skip
sl st(s): slip stitch(es)
st(s): stitch(es)
tr: treble crochet (dtr in U.K. terms)
WS: wrong side

Special Stitches

Shell: work 7 double crochets into designated stitch or space (in U.K. terms this means to work 7 treble crochets into designated stitch)

Pattern Notes

Skill Level: Intermediate

Sizing: This dress is written in nine sizes as follows: XS (S, M, L, XL) (2X, 3X, 4X, 5X). Make sure to follow the numbers for your size only. An “x” indicates the instruction is not applicable to your size.

Stitch Counts: Stitch counts are listed after each row/round. If no stitch count is given, there has been no change since the previous row/round. If only one number is provided, it applies to all sizes.

Right Side/Wrong Side: There is a right side (RS) and wrong side (WS) to this fabric. The RS faces you as you crochet all even-numbered rows (the Shell rows).

Turning Chain: The turning chain does not count as a stitch.

Lacy Fabric: Note that this stitch pattern has a lot of stretch due to the mesh ch5-sps. It is normal for your dress to appear quite small as you are crocheting it. This fabric has the capability of stretching nicely to fit your bust and hip measurements.

Armholes: As you crochet your panels, the armholes may seem quite large. This will change once your armhole border is worked; the border rounds worked later on will cinch them in perfectly.

Construction: This dress is worked side-to-side, lengthwise, in two panels (front and back) that get seamed together, then a simple border is added to the neckline and each armhole.

Tester Photos: Scroll down for tester photos.

Pattern Testers

Below is a collection of photos that my pattern testers graciously allowed me to share with you! Below each photo I have linked each person’s social media account as well as listed their particular yarn choice and any notes they left regarding how well they thought it worked in the pattern. Thank you so much to all these lovely testers who helped make this pattern as clear and easy-to-follow as possible!