To find the side length of a square garden given its area, you can use the formula:
\[ \text{Area} = \text{side length}^2 \]
Given that the area is 169 ft², you can set up the equation:
\[ 169 = \text{side length}^2 \]
To find the side length, take the square root of both sides:
\[ \text{side length} = \sqrt{169} = 13 \text{ ft} \]
So, the side length of the garden is 13 ft.