Take one of the arm covers with you to pick out throw pillows or fabric to makeor have them made.

Funky mix...

If your style is vintage, you could do a short panel that stops just below the window, and use "ties" rather than drapery rings. I suggest using a very thin, minimal rod. panel/fabric options:
http://www.fschumacher.com/search/ProductDetail.aspx?sku=COS-1
http://www.fschumacher.com/search/ProductDetail.aspx?sku=65740
http://www.fschumacher.com/search/ProductDetail.aspx?sku=64721

If you prefer clean lines, you could do a simple neutral linen panel, and add a punchy accent band in the red, or keep it neutral and add a grey accent band.

Here are a couple more that would work. Both are available at Loom Decor. It looks like your wall color is blue? If so, the blue and tan damask would blend but provide some contrast because of the tan. If you want something more neutral, the second one relates thematically to the chintz, but is a little more contemporary.

I'd go for a plain colour that is within the floral pattern on the couch for the pillows and curtains.

Something solid of course but stripes would work too.

Scale is the key to coordinating patterns. If your original print is medium to large, then use a solid or small print. Or a narrow stripe would also work beautifully. Balance pattern sizes, that's the key. I make draperies for a living and I can tell you that your treatments should not only compliment your style, but should be proportional to your windows, i.e., long narrow windows scream for a pair of full length panels. Wide, shorter windows can handle a valance much more readily. Of course all situations have exceptions, but I truly believe you should trust what you love. If you don't LOVE the fabric, you will regret it in 6 months. Use only what you love! Good luck.

How about a check, gingham or a dot? In a reverse color scheme. Lighter background, darker print.

This article has a lot of good info to help you out
https://www.houzz.com/magazine/pattern-play-mix-prints-for-a-traditional-modern-look-stsetivw-vs~967612

You need a block print. Either a stripe or a check to break up the floral. Pull out the lighter tones in the sofa to contrast the crimson. Make sure the new fabric has the crimson, just in smaller amounts.

Curtain panels: the striped linen that Aja sugested is good. This links to the sofa fabric but doesn't compete with it.

Cushions on sofa: a plain grey-green that matches the leaves on the sofa fabric plus a warm beige/cream with fine checks in red (and the green if you can find it). Keep the colours light and any pattern subtle and small scale as the main fabric is big and bold. Find somewhere else in your home to use the cushions you have as they are nice but don't work on the sofa.

It is important to get the texture right too not just the colour so look for linen or cotton and avoid shiny finishes.

Perhaps a simple floral design in cream and red such as this cherry blossom pillow.

Take a look at the window treatment in this charming room with red chintz textiles. I like the color blocking with plaid tie backs. Also notice the fun throw pillow that mixes chintz and animal print.

Darzy and michi, great ideas to update a chintz.

Okay if you like more traditional I suggest stripes, they are refined and gorgeous
http://www.amazon.com/Regal-Collections-Windsor-54-Inch-84-Inch/dp/B004BDON0K/ref=sr_1_31?ie=UTF8&qid=1357423885&sr=8-31&keywords=red+curtains

If a plain color as to focus more on the couch I would go with a shimmery gold like this

http://www.amazon.com/91146-Polyester-Drapery-42-Inch-96-Inch/dp/B001IZJW6O/ref=sr_1_13?s=home-garden&ie=UTF8&qid=1357423960&sr=1-13&keywords=gold+curtains

I don't believe a floral is the best idea, it would clash with the sofa and will look tacky unless you are going for a multi-floral quilt thing, but I don;t think you do

You would have to be very adept at mixing pattern to pull this off. These days rooms are not a mix of florals and stripes and plaids like they were in the 90s and 80's. As a few posters have suggested, solid color, or the color blocking that michi above suggested will be more successful.

Try a grey with white arab patio style print/ trellis print. But do make sure that it is a larger scale than the pattern on your sofa, i would link some umages but i hvnt figured out how to do that yet :(

How about a simple linen panel with a band of color?

The mixing of florals, plaids, stripes, and calicoes predates the 1980's [Julie Thome Draperies, Inc.]

It is classic Americana.

It is warm and inviting.

It does take more skill and effort, but I prefer it immensely over the IKEA or Pottery Barn cookie cutter look.

Love the idea of some stripes in there. I think stripes and florals are an easy way of mixing prints if you're not confident with it (we have stripes throw cushions on our paisley bed). Also, some of the ikat prints could work if you want something more contemporary. Or another floral pattern that has a smaller repeat and is in one colour - or even something a bit like a small toile?

Go to a fabric store (JoAnn's if you have one). Or look on line under Waverly Fabrics. They have tons of coordinating fabrics.

If you have a pattern like this floral that's very busy and add more patterns like stripes or plaids that match, (unless you love the 90's country look or are going for a french country design) there's a good chance it will end up feeling confusing and "overtly busy". I'd pull the lighter colors out of it, thinking I saw a cream, grey, or beige and use a bit of texture in a solid color, sticking mostly with neutrals and you'll find it to be calming and cozy. Let the fabric not the color speak to you in the accent pieces when you already have a bold color and pattern in the room. Simplicity can be welcoming and relaxing when done right it need not be boring.

I'm all for the chevron!!! If the color is off slightly, better yet. It will give it punch!!

Depends on the look you want. Are you trying to update the look of this floral couch? Or keep with the cottage casual look? If you want to update, I would stick with the linen look, color blocking several posters have suggested. Yes, mixing patterns has always been around, but some of the floral/stripe/plaid looks offered suggest a specific past time period. If you want to invest in a new look, I would not go that direction.

Be sure to not forget the neutrals and solid colors.........I love to "pattern play", but have to remember to add solid colors.

I think that you need to be careful with this. It can end up looking like a fabric store instead of your living room.
Take your arm cover (if you don't have one, take one of the pillows or worse case, look under the couch and you will find a small piece that you can cut off.) It is important to have that so you can match. Then, go to the store and ask for help. I have even asked the most color coordinated female customer for assistance.
If you don't want to sew your curtains, a store like Bed, Bath and Beyond would work for that, And, personally I would do a solid. Use one of the lighter colors in the fabric. It will keep your room bright. I actually bought my drapes from Lowe's. They are a taupe twill panel and will go with almost any room! I also love the stripes idea and if you do that, you could buy an extra drapery panel and cut up the panel for a pillow.
Don't use that for your pillows exclusively, though. Too much matchy - matchy is not good. Use one of the deeper colors for another pillow or two. I would also try a different textures. Try a twill or linen along with a chintz and maybe a washable silk.
Your couch pattern is pretty. I was taught that you can use different florals as long as you use the same or mostly the same colors. So, you could use 3 of the 4 colors from the couch but you would not add a new color such as blue, etc. The other part to making it work is that you need to vary the floral pattern size but stay with similar flower style. So, a calico size floral and a daisy size floral would work with your larger flower couch. As Aja said, though, there is a technique to it and you must be careful to coordinate the colors.
Please post your results. I really want to see what you do with it.

I don't see where, if anywhere, where you indicate whether you are talking about custom window treatments or ready made. If you are talking about custom window treatments then I would go with a neutral with a splash of red, blue or gray in an accent band or color block. If however, you are talking about ready made then I would probably go with a solid as opposed to a pattern. I don't think there will be many ready made choices that have color blocking or banding on the vertical edge. Here are some from restoration hardware. They come in many colors but I would pick a neutral that matches the flowers in your couch. You can pick from cotton, linen, velvet etc... and all types of headers pleated, grommets etc... and they are having a sale. If you can sew you could add your own banding on top or other trim to bring in another color.

See link
http://www.restorationhardware.com/catalog/product/product.jsp?productId=prod690596&categoryId=cat1590004

Many different fabrics work with chintz the important thing is the scale of the other fabrics used together. Go with huge over scale prints or very small prints in the same colors from the sofa fabric. Pulling out the other colors. The back from the past new look is flame stitch fabrics which would be great, stripes,plaids, geometric s, and heavy textured solids. Curtains in sheer solids or linens using bamboo roll ups would be very traditional updated look. Kevin, a retired Designed & Buyer

Select any color in your chintz and get it in a plaid, check, stripe or window pane plaid print. Choose one with the lightest color in the chintz as your background or the room will seem to heavy with the dark chintz.

Other chintz patterns, too - as long as the various florals pick up each other's colors. This idea looks best when you go completely over the top with it. Think English country cottage or cozy estate drawing room. Add some same color stripes & solids, for visual relief, and some tasteful antique chairs, tables, vases (or items that pass for antiques) and you will have a very classic upscale look.

I would choose a fabric with most of the colors in a plaid..., a stripe, or what I call a mini print...the mini print would maybe have two-three of the colors from the main ( your sofa fabric) fabric and the stripe a couple of other colors from the main print then the plaid as many as you could get...then you have all of the solids to choose from as well from the main fabric (sofa) that will help fill some the larger items such as window treatments...good luck!

I didn't read all the comments but if you like pattern I would go with a geometric pattern in the curtains to complement the couch not more floral, so like a lattice pattern, chevron or stripes. Maybe with yellow and white or green and white or pull an accent from the couch...but it will have way more impact then a mix of competing florals.

Original post is 18 months old.

Just realized that. I wish they'd retire these old posts. Or archive them for people to access on their own. They show up on my home page and I think they're new. I need to pay more attention