Planting herbs in raised garden beds is now very popular.
Growing vegetables in raised garden beds is even more popular and there are several reasons as to why this is so.
The two main reasons are that:

1. it is much easier to tend a garden bed that is higher than ground level and older folk especially find this so.
   Herbs are grown because the gardener or householder likes to use herbs on a regular basis and a raised garden bed allows for a person to pick herbs on a regular basis without the backbreaking bending over to do so.
   
2. the new soil that is put into the garden bed is a lot superior to the soil in the garden that has been there for many, many years and been depleted of many of the nutrients required for good healthy plants.
   

Easier to tend With the raised height it is much easier for older folk to reach, but even people who are not older find that it is easier to spend a longer time tending the garden when not having to get down to ground level.
The height of the garden bed can be about 18 inches where the bed is brought straight up off the ground with some side walls, or it can be a garden which is set up in large containers where the containers are raised up off the ground and the height of the garden level itself may even be at waist level.
Better soil Because the soil is being added it is usually far superior to what is already in the yard.
It most likely has been treated meaning that weeds and pest will be at a minimum and it will most likely have had nutrients added to it as well.
Often when growing vegetables in a ground level garden the soil has had the same or similar plants being planted in it year in, year out and the soil has been depleted of the nutrients that are required for the particular plants that are being grown there.
Although planting herbs does not require top quality soil, having fresh soil will still be a benefit in helping grow strong healthy herbs and most definitely having a higher garden to tend and pick from, will also be appreciated with a raised garden bed.