How to Join Northern Diamond Granny Squares: Step-by-Step Guide

How to Join Northern Diamond Granny Squares: Step-by-Step Guide

If you've ever taken on a granny square blanket, you know that joining those little beauties can make or break the project. Northern Diamond Squares have a unique look, and joining them the right way lets your hard work shine. In this post, I'll walk through exactly how I join Northern Diamond granny squares—line by line and corner by corner. This method keeps seams flat and neat, perfect for a crisp, finished blanket.

Whether you're joining your first set or just want a smoother, flusher finish, these tips will help make your blanket assembly easier. Let’s dive right in!

Understanding Northern Diamond Squares and Project Setup

Northern Diamond granny squares have a distinctive geometric look that's eye-catching and modern. When I start prepping to join my squares, I find it so much easier to work with smaller sections. Wrestling a giant blanket is no fun, so joining as you go (square by square) keeps everything manageable.

Tip: Weaving in ends square by square is so much easier than fighting with loose tails after you’ve joined the full blanket.

Preparing Your Squares and Yarn Tails for Joining

Organization is my best friend during joining. I separate my squares into two stacks:

• Squares with long tails (for sewing)
• Squares with short tails (no tail left for sewing)

I like to use up the short-tailed squares first by pairing them with a long-tailed square. That way, I don't waste yarn, and I keep everything tidy.

Square Prep Steps:

• Sort squares based on tail length.
• Stack short-tailed squares to use up first.
• Stack long-tailed squares set aside for sewing.

Threading Your Needle for Easy Joining

Threading your yarn doesn’t need to be fiddly. Here’s my go-to trick:

1. Loop the yarn over your needle.
2. Pinch the yarn gently with thumb and finger to make a slim yarn tip.
3. Slide this tip right through the eye of the needle.

A bent tip blunt needle makes this process smoother and stops you from splitting the yarn when sewing.

Positioning the Yarn Tail: Getting Started at the Corner

Before you sew your seam, make sure the tail is right in the corner where you want to start. If the yarn is sitting off to the side, I just slip the tail into the center chain of the corner for a direct edge start. This helps the squares line up perfectly.

(If this is your first time, a small sketch or photo showing the yarn tail sitting cleanly in the corner can be helpful.)

Matching Corresponding Stitches for Flat Seams

For a neat, flat seam, matching up the stitches in the corners is key. I always find the center of the corner chains on both squares, making sure to use only the back loop of each stitch. This helps the seam sit flush and crisp.

Pro Tip: Always double-check that both corner chains align before moving up the seam.

Sewing Along the Seam: Stitching Technique & Handling

With my corner stitches matched, I sew through the back loop from one square, then immediately through the back loop of the other. Repeat all the way along the seam. The bent tip of the needle helps poke straight down into each loop. I keep the stitches snug but not tight.

You don't need to worry about the seam’s tension right away. Just keep everything lined up and handle the yarn gently.

Tightening the Seam Without Warping Edges

After sewing an inch or two (about as long as your finger), I gently snug up the seam. If you pull too tight, the edges will bend inward and pucker. The aim is a seam that’s secure and flat.

Common Tension Tips:

• Don’t yank the yarn—gentle tugs are plenty.
• Keep the seam flat, not puckered.
• Smooth seams always look neater.

Consistent Seaming: Back Loop to Back Loop

Every stitch along the seam should go from center out, back loop to back loop. I check every few stitches to see that I’m still aligned and both rows are staying straight. If you find a mismatch, you can fudge a little, especially on either side of special stitches.

A simple visual stitch guide helps keep beginners on track.

Dealing With Special Drop-Down Stitches

Halfway up the seam you may hit a spot where you dropped down for a longer stitch in your square pattern. I like to make sure these larger stitches are aligned on both squares, even if I have to fudge one side to make it happen.

FAQ:
Q: What if the stitch counts don’t match up perfectly?
A: Prioritize the drop-down or feature stitches for alignment. You can fudge the plain stitches on either side and it’ll still look great.

Creating One Long Stripe From Joined Squares

Joining square by square, you create one long stripe that forms either the length or width of your blanket. I always leave the working yarn tail hanging at the end. I might use it for future joins or knotting off when I’m ready to finish the next row.

This approach is perfect for large granny square projects because you never have to handle a full blanket until the final assembly.

Preparing for Joining Additional Rows

Once you have a strip the length you want your blanket, you’re ready to add the next row of squares. I like to stack all my finished stripes and keep them tidy, tails tucked so they’re ready for speedy joining.

Aligning and Joining a New Square to the Strip

To start attaching a new row, I keep the long strip on my table (or lap) and bring the new square close to me. I make sure my needle is threaded and the yarn tail sits at the corner’s back loop, just like before.

By always keeping the “working” strip above and the new square below, I avoid twisting or mismatching.

Sewing Up the Vertical Seam of the New Square

Using the same back loop-to-back loop stitch, I work up the side seam of the new square. If I run into a knot or extra tail, I just pick a bit of solid yarn to secure the edge and then get right back to matching back loops for the rest of the seam.

Snugging the Seam as You Go

After sewing up a stretch, I pause to tighten the seam a little. Flatness is the goal. Avoid pulling corners too hard, or you’ll see them start to curl.

(A before-and-after photo can really help show how the proper tension keeps seams invisible!)

Joining Kitty Corner at Vessel Points

When you hit a spot where four squares meet, joining “kitty corner” is super important. I look for the back loop on the opposite corner, slip my needle in, stitch through, then come back into the new square to keep it all joined and snug.

A strong diagonal connection here keeps blanket corners neat and durable.

Securing the Seam with a Placeholder Knot

At each corner, I make a tiny “placeholder knot” by looping the yarn back through the loop just made. It’s not as tight as a full knot—just enough to hold things together while I keep joining.

Placeholder knot: A light loop that holds your seam in place, easy to untie later if needed.

Preparing the Next Square

Before stitching your next square onto the row:

• Thread the needle
• Position the yarn in the square's corner back loop
• Move any old tails out of the way

Check that the new square is oriented the right way (especially if your pattern has a direction).

Sewing the Long Seam Up the Next Square

Work edge to edge, always connecting corresponding back loops. The fabric might start to fall off your workspace as strips grow, so I pause often to re-set my work area and prevent pulling or stretching.

Managing Corners for Smooth Joins

Corners can look strange and messy at first, but don’t stress. Gently shrink the seam at the corner, but don’t go so tight that the blanket bunches. Once you move farther away from the corner, the join will settle in and look flat.

Encouragement for Beginners: If your corners look odd at first—that’s normal! Just keep going and they’ll smooth out.

Completing the Side Seam: Final Corner Stitch

As you stitch to the last corner, make sure both corners are aligned right. Pull the last few stitches gently, so there are no gaps or bumps. Sometimes I run back through the final corner stitch for extra stability. At the end of a row, a diagonal (kitty corner) join keeps squares flush and prevents holes.

Warning: Avoid over-tightening seams at the finish—hard seams can make the blanket stiff.

Securing Final Stitches With Light Knots

At the end of your row or strip, use a soft knot or placeholder to prevent your work from unraveling. Never make traditional hard knots here. Yarn tails should stay flexible and easy to weave in later.

Knot tension tip: Tight enough to hold, loose enough to undo if needed.

Moving Along the Row: Keeping the Rhythm

As you repeat threading and joining, each square falls into place. A steady pace and a rhythm of checking corners and snugging seams keeps everything tidy. I track my progress with a mini checklist as each row is finished.

How to Join Rows Together

After you’ve completed enough rows, it’s time to start joining strips together. Whenever I join a new row, I double-check orientation to keep the pattern consistent. Matching up the corners diagonally is extra important; it makes for a beautifully seamless finish.

(A diagram here can help illustrate row-to-row joins.)

Tools and Notions for Easy Joining

My  includes:

• Bent tip blunt needles for precise seaming
• Sharp tip needles if you like extra accuracy
• Needle threaders to make starting fast
• Small scissors for trimming tails
• Project baskets to keep everything organized

You can find a collection of joining tips and products at Joining & Techniques.

Yarn Tail Management Strategies

Keeping your tails under control makes joining easier and neater:

• Use up short-tail squares first
• Stack long-tail squares for sewing
• Secure loose tails gently to avoid tangling
• Don’t knot ends until all joining is done

Seam Tension: Getting It Just Right

Smooth and sturdy seams last longer and look better. Here’s what I keep in mind:

• Start with relaxed tension; tighten after 1-2 inches.
• Tight seams pull edges inward; keep ajusting for flatness.
• Soft snugs result in the flattest, most durable seam.

(Illustrations comparing seam tension can really show the difference.)

Handling Mismatched Stitch Counts and Odd Joins

Not every square comes out identical. Sometimes, stitch counts just don’t match. If that happens, focus on these:

• Align important points (like corners)
• Skip or double a stitch to keep evenness
• Don’t sweat minor fudging—flatness matters more

Problem Solving: If things are way off, gently undo a few stitches, make your adjustment, and resew.

Workflow Tips for Large Blankets

Making a blanket with loads of squares? Join strips first, then combine. It keeps your work portable and less confusing.

Workflow checklist:

• Join small strips (3-5 squares)
• Combine strips into larger sections
• Use placeholder knots between steps
• Roll finished pieces for easy storage

Workspace and Setup for Comfort

• Keep what you’re joining above your hands, the new square closest to you.
• Good light and a comfortable seat make stitching much more pleasant.
• If your work tries to slide off the table, use clips or trays.
• Take stretch breaks to avoid hand fatigue.

Troubleshooting Common Joining Issues

Loose seams? Gently snug down with the needle.
Split yarn? Unpick, retwist the yarn, and redo.
Broken yarn? Knot with a new tail and continue.
Uneven rows? Undo a bit and check stitch placement.

If something looks off, fixing early saves trouble later!

Why Back Loop Seam Joining Looks Amazing

Joining through the back loop only keeps seams flush with the blanket, so there’s no bulky ridge. The result is a smooth, professional-looking finish—your Northern Diamond granny square blanket lays flat and doesn’t feel lumpy.

(Photos comparing back loop vs. full stitch joins can be a great visual reference.)

Trying the Seam on Other Crochet Projects

This back loop only joining method isn’t just for Northern Diamonds. It works beautifully with any granny square or even strips of crochet. It’s my favorite for durability, flatness, and simplicity.

Leaving Tails for Later Finishing

When I finish joining, I always leave tails long enough to weave in or tie off neatly after the blanket is fully assembled. No bulky knots—just tidy weaving for a comfy, pretty finish.

Finishing Checklist:

• Leave at least 4 inches of tail for weaving
• Use a blunt needle to hide ends in the row
• Snip excess close but not too close

Weekly Tutorials, Live Chats & Crochet Community

I share tutorials every week on The Secret Yarnery YouTube channel and love connecting with other yarn lovers. There are live chats every Friday and podcasts on Wednesdays—great places to catch new tips and ask questions.

If you want to dig deeper on joining granny squares, check out the Joining Granny Squares - the Ultimate Guide! playlist.

Sharing Your Work and Getting Connected

I always enjoy seeing what others are working on. Share your progress and finished Northern Diamond granny square blankets by tagging @secretyarnery on Instagram or joining our friendly Facebook Crochet Community Group.

Use the hashtag #NorthernDiamondBlanket to gather inspiration and connect with other makers.

My Favorite Tools For Crochet Assembly

Here’s what keeps my joining running smoothly:

Storage and preparation make even large granny square projects manageable!

Quick Reference: Key Joining Steps

1. Sort and stack squares by tail length
2. Thread needle, position yarn tail in each corner
3. Align center back loops, sew back loop to back loop up the seam
4. Snug seam every inch or two
5. Join corners diagonally (“kitty corner”) for closed joins
6. Add a placeholder knot to hold in place
7. Repeat for next square or row

Keeping Motivation Strong for Big Joining Projects

Joining a granny square blanket takes time and patience. I break it into smaller milestones—one strip, one row, one corner at a time. Taking music or podcast breaks—or catching up on a favorite podcast—also helps things move along and keeps spirits high.

“Progress, not perfection. Every joined square is a win!”

Common Mistakes to Avoid

• Splitting yarn strands with the needle
• Pulling seams too tight (makes edges pucker)
• Failing to align corners (“kitty corner” joins)
• Making knots too tight—hard seams never feel cozy

(A simple visual or infographic alongside your work area can help remind you!)

Salvaging Mistakes and Adjusting Seams

If you catch a mistake:

• Loosen seams gently with the needle, don’t rip
• Re-align rows and corners as needed
• Re-join with proper tension
• Only add knots if you’re confident you won’t need to adjust again

Hand-Sewing vs. Other Joining Methods

There are lots of ways to join granny squares: slip stitching, crocheted joins, or even whipstitching. Personally, I like hand-sewing through the back loop for these reasons:

Hand-sewing lets you adjust tension as you go with minimal ridge or bulk.

Visual Guide: The Back Loop Explained

Each crochet stitch looks like a V—when you’re sewing, pick up just the back loop (the strand farther from you) of both squares. This is the secret to flat, seamless joins.

(Annotated diagrams can help clarify if you're new to this technique.)

Staying Neat While Working

During assembly, I like to keep tails pinned to the backs of squares, toss excess yarn into a basket, and do a quick tidy whenever I finish a row. This reduces tangles and makes the next step easier.

Speed Up Your Joining: Efficiency Hacks

• Pre-thread several needles before you begin
• Group squares by tail type for fast sorting
• Use ergonomic tools to reduce fatigue
• Set daily or weekly goals for sections

Joining and Blanket Shape

Tension matters! If seams are too tight, your blanket will scrunch up and lose its shape. By checking row lengths and adjusting pulls as you go, you’ll keep corners square and edges neat.

(A row-measuring tape helps spot size issues early.)

Seasonal Ideas and Gift Suggestions

This joining method works for baby blankets, lapghans, throws, festive decor, and more. Multiple color combinations make it easy to tailor to your giftee or room theme.

(Search Pinterest or Instagram for more colorway inspiration!)

FAQs:

Q: What’s the best join for Northern Diamond squares?

A: A hand-sewn back loop only seam. It stays flat, hides well, and keeps the diamond lines crisp.

Q: Which needle should I use?

A: A bent tip blunt needle. It slips into the back loops without splitting yarn.

Q: Can I join squares without tails?

A: Yes. Attach a new length of the same yarn, leave a 4–6 inch tail, and weave it in later.

Q: How long should my tails be for sewing?

A: Aim for 4–6 inches for weaving only, 18–24 inches if you plan to use the tail to sew one full side.

Q: Do I start in the chain spaces or the stitches?

A: Start in the center chain of the corner on both squares, then continue stitch by stitch up the side.

Q: What if my stitch counts don’t match?

A: Align corners and key “feature” stitches first. Fudge on either side by skipping or doubling a plain stitch.

Q: My corners look bulky. What did I do wrong?

A: You likely tightened the corner too much. Loosen the last few stitches, re-seat the corner, and re-snug lightly.

Q: How do I join where four corners meet?

A: Do a kitty-corner stitch: take a diagonal stitch through the opposite corner’s back loop, then return to your path. It closes gaps.

Q: How do I fix a wavy strip after joining?

A: You over-tightened or mismatched stitches. Unpick a short section, relax the tension, and realign back loops.

Q: What yarn works best for this join?

A: Use the same yarn as the squares for perfect color and stretch. If you must switch, pick a similar weight and fiber.

Q: Can I mix different yarn brands in the join?

A: Yes, as long as weight and fiber behave similarly. Test a small section to check stretch and colorfastness.

Q: What if the seam shows on the right side?

A: You might be catching front loops. Recheck you’re in back loops only and keep tension even.

Q: How do I keep orientation consistent across rows?

A: Always place the joined strip above and the new square below. Check the direction of your diamonds before each seam.

Q: What’s a placeholder knot and when do I use it?

A: It’s a light loop to hold tension at corners. Use it to park your work; it should be easy to undo later.

Q: How do I prevent tangles while joining a long strip?

A: Keep the working yarn in a bowl or zip pouch, pin tails to the back, and reset your workspace every few inches.

I’m Christa, the maker behind The Secret Yarnery. I design simple, modern crochet patterns and teach step-by-step tutorials on YouTube every week. My goal is to make crochet easy, fun, and stress-free, whether you’re on your first granny square or your fiftieth blanket.

When I’m not filming tutorials or hosting live chats, I’m testing yarns, organizing projects into tidy baskets, and finding faster, neater ways to join squares. I love clean finishes, practical tips, and cozy, colorful makes.