There are many reasons to create raised garden beds. Raised beds allow for gardening in tight spaces, planting seeds or seedlings much closer together, leading to less weed growth. The beds can be anywhere from 6 inches to waist high, the higher beds being easier for people with back or knee problems to enjoy gardening.
We had a long narrow space along the side of our garage that was a breeding ground for catnip, thistle and dandelions. We also had some good topsoil that needed to be used. So we built some 3 foot wide boxes and transplanted our herbs to this formerly wasted space.
First, the weeds needed to be pulled, and the area leveled. Then. we put down landscaping felt. Next, the box was put in place and filled with good, black dirt. Finally, we put the plants in.
We chose herbs that love sun and heat. We ended up with four beds, and the plants are: thyme, mint, sage, basil, lavender, oregano and chamomile. We also planted asparagus between the boxes, just to see how that would work (we'll know in about 2 years).
We gained approximately 120 square feet of gardening space by creating raised beds. The area our herbs used to inhabit will now be used for more vegetables.