Guitar players are real finger gymnasts. Without proper finger stretching and flexibility you cannot expect to reach many beautiful chord voicings. Good stretching will benefit your overall playing, so it is important to work on it regularly.
Finger stretching exercises without the guitar
There are some great stretching exercises that you can and should do even before you pick up the guitar. Here is an excellent video demonstrating those:
Stretching exercises on the guitar
Once your hand and fingers feel warm and loose it is time to take the stretching to the guitar. The exercise below is taken from Creative Guitar 1: Cutting Edge Techniques by Guthrie Govan (affiliate link):
Difficult part is that you have to keep all four fingers on the strings all the time. That’s really the point. How else can you get stretching!
You start with a Emaj7 chord and move the fingers one by one until we reach Ebmaj7 chord (same chord shape but one fret lower), then do same maneuver, one more time, one more… continue until you reach the nut. As you move closer to the nut the distance between frets increases thus your fingers will have to stretch more. Take it easy, and don’t go beyond comfortable. Last thing you want to do is hurt yourself.
You don’t have to start at the very bottom of the neck. Start with any position that is comfortable. If you get stuck anywhere on the way try going back 2-3 frets and work your way up from there again. Remember that reaching the nut is a long term goal. It might take several weeks to get there.
Be careful with this exercise! Make sure your hand is warmed up well before doing any stretching. Chromatic exercises as well as legato runs are a great way to get your hand loose and ready for stretching exercises.