Quick fix: Rip out and recast using a needle 1 size smaller than your project needle, holding the yarn firmly around your thumb. Switch back to the project needle for row 1.
What you are seeing
The cast-on edge is floppy and wavy, oversized compared to the knitting above it. The first row is awkward to work because the stitches slide and shift. In a finished piece the edge may flare outward.
Why it happens
- Too much slack between cast-on stitches
- The backward loop cast on, which is inherently very loose
- A relaxed thumb wrap during the long-tail cast on
Fix it now
- If in early rows: rip back to the cast on and redo with a needle 1 size smaller.
- After each cast-on stitch, slide it snugly toward the needle tip before forming the next stitch.
- Switch to your project needle for row 1.
- For a finished piece: pick up stitches along the edge with a smaller needle and work 3 rows of garter or ribbing to stabilize the edge without ripping out.
Prevent it next time
- Use the long-tail or cable cast on instead of the backward loop — both are far more consistent.
- After each cast-on stitch, snug it to the needle tip without pulling tight — just enough to close the loop.