The garden is a battle scene. The plants that grow there occupy space quite differently. In their lifetime they fight for survival using various methods or tactics to beat each other out. Divided into three groups, these survival concepts are studied as part of plant ecology and the gardener gains tremendously in the day to day care of their garden when they understand these strategies. Not every plant falls squarely into the confines of one group, in fact many share tactics and these can be out most aggressive garden plants as they fight for survival in more than one way.

The first group of plants are called the competitors. The perennial competitor grows rapidly. Their foliage is often soft and large, intended to push aside neighbors. Time is initially spent occupying space and flowers often arrive late in the season. Their late flowering stems can become heavy with flowers and subsequent seed pods. This is yet another tactic to gain ground, leaning against neighbors to push them aside. We often think of this as a weak stemmed plant, when in fact it is just another strategy. Winter finds their dried up leaves holding ground. Without our cleanup, the occupied space would keep weed seeds from gaining access to the ground. Examples include lamb's ears, silphium, Joe-Pye weed, and petasites. Many of these perennials are best planted in large group as they tend to bully other plants.

The second group are the stress tolerators. Our best perennials fall into this category. Stress in our climate can be heat, drought and humidity. Stress tolerators may have small leaves or coated foliage, able to conserve moisture. In a shady situation they may have evergreen leaves, taking advantage of the sun when trees are dormant. Examples include helleborus, Solomon's Seal, sarcoccoca, and peonies. Within this group, one finds the stress avoiders, our bulbous rooted plants like daffodils and tulips. Able to tolerate inhospitable situations with underground storage units, they also attempt to bookmark their space by producing copious amounts of foliage that smother plants that try to grow underneath as they go dormant. The idea being, I will be back and this is my spot. Since they actually only grow for a short season, it's more imperative that they play the suffocation game well.

Lastly we have the ruderals or pioneers. Fast growing, the flowers are usually showy and bright. Life is short, usually a year or two and copious amounts of seed are produced, insurance for future generations. Ruderals tend to fill open space quickly and often become weedy offenders. Examples include Lychnis coronaria or rose campion, verbena bonariensis, larkspur, Maltese Cross, and foxglove. Seed prefers to germinate with light, another words, they can be extinguished by layers of mulch (once seeding has occurred). Quite a few ruderals are choice garden plants, two examples are Phlox divaricata and Papaver somniferum.

The intermingling of perennials is exactly what makes a garden, yet the battle to control them becomes our everyday mantra. Competitors are best planted in large groupings, essentially competing with themselves. The stress tolerators become our key structure plants. A gardener's good citizen, they thrive despite the weather. Lastly the ruderals have their merits, yet move around in random patterns, seeking open ground. Many purposely seed in fall, knowing that winter offers the ideal season for open space. Knowing what kind of plant we are managing helps us know what might happen next. The battle lines in our gardens are at the edge of each plant. If we could just draw a line in the dirt, dare the offender to cross, how much easier gardening would be.

This article is from a series of lectures Karen Rexrode gives at Green Spring Gardens in Alexandria, Va. The content is derived from the book "Planting Design" by Piet Oudolf. This years lectures are based on Piet Oudolf's design strategies and Karen's garden observations. The lectures include indoor and outdoor lessons.