Like many organisms, plants come in a wide variety of shapes and sizes. As you assess and plan your garden, it is important to understand how big your plants will grow and how long it will take to reach a mature state.
If you plant too close, there will be increased competition for air space, water, and soil nutrients. This can cause healthy plants to be more susceptible to diseases and reduced vigor, growth, and yields.
On the other hand, if you plant too far apart, the garden can look disproportionately empty and weeds are more likely to emerge in open/bare spots of the landscape.
When planning and maintaining the garden, gardeners must strike a careful balance so plants do not have to be consistently moved or transplanted if planted too close together or spend too much time weeding or filling in a bare spot if planted too far apart.
Understand that plants grow at different rates. Perennials may take a few years to reach their mature size, while annuals can grow significantly in just one season.