This is a common problem and in some cases (e.g. mullein leaf) it is impossible to cover the herb with alcohol at a 1:3 ratio without using specific equipment or the percolation process instead.
What you can do is:
1. Grind the herb to as close to a powder as possible. Try using the 1:3 ratio and if this still does not work keep adding alcohol and keep track of your measurements so that you know the strength of your final product (1:4, 1:5 etc.) and can adjust dose as necessary.
2. Another idea is that you could try a sterilized weight/press to keep the herb under the alcohol.