Step 1: Open your image from within Photoshop (From within Photoshop, go to open, navigate to your file, At the bottom pull down choose Camera Raw, Your file will now open in Camera raw )
Step 2: Go to the HSL/Grayscale tab (4th tab from the left)
Click on the Convert to Grayscale
Click on the word default to zero out all of the sliders.
Drag both the Yellow and Green sliders all the way to the right to 100%
Step 3: Pull the Blues slider all the way left to -100%
Pull the Aquas slider all the way left to -100% (this will sometimes make a difference, but it may yield no change)
Step 4: Go to the basic tab (first tab on the left)
We can now attempt to darken the skies and brighten the foliage.
Slide the White balance slider to the left (towards the blue side) Darkens skies
Slide the tint to the left (towards the green side) Brightens image, increases detail on foliage
Step 5: Adjust the Shadows and blacks to help further brighten grass and trees.
Slide the Shadows slider to the right to open up the Shadows
Slide the Blacks slider to the right to open up the Blacks, you may have to go back to the left to bring some detail back in as needed. (if you don’t see the shadows slider go to the camera icon find the drop down menu for “Process” and set it to 2012 (current) now go back to the basic tab.)
Step 6: Slide the Clarity slider to the left to soften the image for that tell tale Infrared glow (-45 starting point). Slide the Contrast slider to the right to taste, to add contrast back.
Step 7: To finalize your image, go to the FX tab and add noise (grain) to complete the classic Infrared look. Zoom into your image to 100% Slide the amount slider to 30 as a good starting point.