The “mono strum” is a technique that is used by many ʻukulele players to various degrees. However, no person has become better associated with it than James Hill. He use it in some form or another in most of his songs. The best example might be his awesome tune Down the Rideau Canal.
Using a mono strum allows the ʻukulele player to strum all of the strings, but only to sound one (or two) note(s) at a time. How this works is: you hold only the one note you want to hear and mute the rest of the strings. Of any technique, this one probably takes the most experimenting. The reason being that every note you play will need different hand positions for muting. Keep in mind that there is no right way to mute the strings. You can use your thumb over the neck for this technique!
When you tab out a mono strum for ʻukulele it will look like this:
>>>Ex1 Ex2 Ex3 Ex4
Start by fretting the note that you want to hear. Now you have to figure out what fingers are going to mute the strings.
For Ex1 I would fret the G note with my ring finger, mute the top two strings with the pad of my thumb, and the bottom string with my 3rd (leaned over). For Ex2, again I would fret the note with my 3rd finger, mute the top string with my thumb, and the bottom two with my 3rd (leaned over). Ex3 gets my thumb on the top string, middle and index fingers on 3 and 2, and my third finger holding the E note. For Ex4, I would play the note and mute the rest of the strings with my ring finger (leaned over), using my index and middle as backup “muters”.