Infrared photography captures a part of the light spectrum that can't be seen by the naked human eye. (More details here: https://en.wikipedia.org/wiki/Infrared_photography)
Spring is a great time to make IR photos since the foliage is lighter and appears more radiant than at other times of the year. Most IR photography is done in black & white, and yields images with dark skies and brilliant white clouds, and shimmery white foliage. But color IR is also possible, where foliage is rendered pink or red.
There are a few ways I know of to achieve IR effects in photography:
(1) Use a digital camera (set to black & white mode), with an IR filter. This is probably the easiest way to do it.
(2) Convert a digital camera to shoot IR permanently. This trick only works with certain cameras, and may be best left to someone experienced at the task.
(3) Convert an image into a faux IR photo using software. While you can produce a pretty convincing image this way, it seems the least authentic to me.
(4) Shoot using IR film. Ilford currently makes a "near-infrared" black & white film called SFX that gives a close approximation of the real thing when used with a red filter. Unfortunately, other IR films are no longer being manufactured, although you may still be able to find some types online (expired): Efke IR, Kodak HIE and Konica IR films can sometimes be found. It's pricey when you can find it, but Kodak also made a color IR surveillance film that produces amazing effects. (I have no experience with color IR in digital, so maybe someone else can offer suggestions in that regard.)
Most people will probably find it easiest to pick up an inexpensive lens filter for their DSLR. You can just set your camera to shoot in b&w, focus (be sure to set the lens to manual focus once you've locked on your subject), then attach the filter. Since IR filters are opaque, you won't be able to see to focus after you screw it on. As with all filters you can spend a small fortune here, but you can buy a decent filter for $25 or less on Amazon. I use a $12 Neewer brand IR760 filter.
Your exposure will be long, so you'll definitely need a tripod or other support for your camera when shooting IR. Finding the right exposure settings may take some experimentation, but the results can be striking. Here's an example of a photo I shot a few years ago using a Nikon D7000: https://www.flickr.com/photos/lancekingphoto/9300214188/in/photolist-nw2bMy-neemFE-faQ2Eu-nvy1yq-niUr8x-nmZiw4-k7GY1x-k9jSqD-bzekza-bk6RzE-buj6ae-btQ2Ap