WHAT IS FORM?
There are three design elements to consider when creating a planting design: FORM, texture and color. Each plant you choose encompasses these characteristics in different ways, but FORM is the most consistent.
Form is the overall plant shape that includes its height, width and depth. All plants have a natural form and the most amazing planting designs embrace plant forms in a vibrant composition. Typical plant forms include oval, round, columnar, spreading, pyramidal, weeping, vase-shaped, plus many others.
As you learn plants it's important to take note of their form, since this aspect is stable year-round (even when a plant loses its leaves), while color is typically more fleeting.