I’ve figured out the easiest way for you to make the blanket you want: An all garter-stitch blanket with vertical stripes, that is 78" long and approximately 60" wide (you said you wanted it about 312 stitches wide, but didn’t say the width you wanted in inches). That’s the same size as the very first blanket I made, and I kept notes, so I was able to do some math to figure out how much yarn you would need. The design I am proposing would not require ANY sewing!
The blanket I made was 79" long and 60" wide when finished (~ the same size as the top of a queen size bed). It was 303 stitches wide, and 486 rows long. I also used #4 worsted weight yarn, but I used #7 needles. So the calculations will be slightly off with #8 needles. Using #8 needles will make it larger. And garter stitch is a little wider than the (stockinette) stitch I used, so that will make it a little wider as well. I calculated that my blanket would use 11 skeins of the yarn that you are using (380 yds each). Using larger needles uses more yarn, so I would approximate that you need at least 12 skeins of yarn to complete your blanket. And I would suggest you use the largest circular needle you can find – 47" is the size I always use for blankets.
So I would suggest you buy 12 different skeins of yarn in the colors you want for the stripes. And then buy 1 more skein to make a horizontal border on the top & bottom edges of the blanket. The borders will make your top & bottom edges neater, and make it easier to add in all the colors for the stripes without any wonky-ness! The borders will also make it WAY easier to cast-on and bind-off in just ONE color, instead of 12 different colors. The color for the borders could be a neutral color - like black, white, or grey - or whatever color you like.
You can knit the whole blanket at once, on your one set of circular needles. The trick is to use the “Intarsia method” of knitting to join your stripes together as you are knitting. Intarsia is usually considered a rather difficult method of knitting, but for this situation, it is NOT difficult at all. You just need to do an Intarsia Join when you come to each new stripe. To do an Intarsia Join you take your OLD yarn (the one you just finished using) and place it OVER your NEW yarn (the one you will use next), and to the left. That’s it! Here is a video: Intarsia Joins by ACTechniques
So here’s the “pattern” for the blanket:
- Cast on 300 stitches using your border color. Knit 20 rows. Cut your yarn, leaving a tail to weave in.
- Start Row 21 with the color of your first stripe, and knit 25 stitches. Leave skein attached to your work.
- Then ADD IN your NEXT color of yarn, and knit 25 stitches. Leave skein attached.
- Repeat this until all 12 colors have been added in. You will be leaving all 12 skeins of yarn attached to your work.
- For Row 22 (and all remaining rows), knit the 25 stitches of your first color. Then put OLD over NEW, and knit 25 stitches of the next color. Repeat for all 12 colors.
- Knit until desired length, or you run out of yarn. (I did the calculations so you will have enough to make it the length you want – 78")
- Then make your end border with the border color and knit 20 rows. Then bind off & weave in ends (you will only have 28 ends!)
Some other tips:
- If you are completely unfamiliar with intarsia, there are lots of videos about it – but most of them will be more complicated than you need for this particular blanket.
- If you keep your skeins of yarn lined up in order, you will not have too much tangling of yarns.
- Here is a video to make beautiful edges on a garter stitch blanket: How to Knit Beautiful Edges by Knitted Ideas
- You should make a small practice swatch with scrap yarn and STRAIGHT needles to get the hang of these techniques, and work out any problems you might have before you start your real blanket. I’d suggest casting on 40 stitches for your end-border (you can make the border any length you want, as long as it is an EVEN number of rows - I’d suggest 10 rows) , and then making 4 stripes - each 10 stitches wide. Knit as many rows as you’d like until you get the hang of it. Then finish up with the other end-border. This practice swatch will not only help you understand the process better, but it will perfect your technique and also allow you to use it for making size calculations for your final blanket.
If you have any questions, or need help, I’m happy to answer. This would be a very beautiful and UNIQUE blanket! Most people won’t knit a blanket like this – they would usually knit it sideways, but that is too many stitches for me to scrunch onto one needle! And the stitches would come out sideways. Simply using the Intarsia Join allows you to knit the whole blanket in the normal fashion - from top to bottom! Best of luck to you!