Blinds, Shades and Shutters - Prevent Headrail Sag on Wide, Arched Window

I have several wide (~50 inch) windows that are arched at the top. I am replacing aluminum mini-blinds with 2 inch faux wood blinds, inside mounted. The minis were obviously relatively light and held up just fine for 5 years with only the two end brackets mounted to the sides of window. The new sets are much heavier and I can immediately see them sagging in the middle without anywhere to mount a center support. Is there anything creative (yet not clunky or detractive) I can do to provide additional support to the headrail when I cannot touch the frame due to the arch? I prefer to keep them inside mounted so as not to cover up the arch (plus I already purchased the blinds for these windows and had them cut to fit as inside mount :eek:).

You have to provide a stiffener to the headrail, such as a piece of wood or metal. Since there is nothing manufactured for this purpose, you will have to make it yourself. Something as simple as a thin piece of wood, like a length of baseboard trimmed down to the same width as the back of the headrail (2") and screwed to the back of the headrail will work just fine. Just make sure that the baseboard is made of solid wood and not vinyl, because it has to be rigid. You can get this at any lumber store, and it comes pre-finished, usually in white.

Another fix is to support the center of the headrail with a length of high test fishing line. Tie a loop around the headrail and attach the other end to the top of the arch. The fishing line is nearly invisible and yet strong enough to do the job.

But...I'm surprised that your blinds are sagging. Most headrails are stiff enough to span 60" and more with no noticeable sag.

Hi and welcome to the forum!
Actually, there is a product manufactured for this called a "Floating Headrail".

You can make something yourself, similar to the above answer, but get a couple of 1 x 2's, or 1 x 3's (or whatever size you need), and have one for the top cover and nail the other piece under the top one, at the back, so it looks like an L. Paint it to match the trim and mount it using L brackets, at the sides. You can attach the bracket things to this before you mount it, if you want.

Test to see if the head will sag by having 2 people hold the blind at each end as you operate the blind up and down. Some heads are made heavier than others.