What should be the spacing between plants in a mixed border?

In landscaping, particularly when designing a mixed border, the spacing between plants is critical for optimal growth, aesthetics, and health of the plants. The recommended spacing of 18-36 inches apart allows enough room for each plant to grow to its full size without immediately competing for resources like sunlight, water, and nutrients. This spacing ensures that air circulation is adequate, which helps prevent diseases that can arise from overcrowded conditions.

When plants are spaced 18-36 inches apart, it also allows for a more natural and sustainable appearance as it accommodates maturing plants and foliage. This spacing can enhance the visual appeal by providing a layered effect, showcasing the heights and shapes of different species while avoiding the harsh, artificial look that can occur with denser plantings.

The other spacing suggestions, while they may seem appropriate for certain landscape scenarios, do not provide the ideal conditions for a mixed border. For instance, spacing plants too closely could lead to overcrowding issues, while spacing them too far apart may result in a sparse appearance, diminishing the design's overall impact.