Intermingling: Expert Tips for Home Garden Design
by Caleb Melchior

When you understand the importance of these aspects of home garden design you’re sure to find success—site conditions, culture, growth habit and aesthetics.

You’ve probably read the term intermingling on a blog or as a hashtag gushing over a European designer’s latest show garden. But what, exactly, is intermingling and how do you achieve this ever-so-desirable planting effect in your own garden?

Rather than clearly defined groups of single forms or species of plants that remain the same from year to year, an intermingled planting has groups of plants with fuzzy edges that change and shift over time—sometimes to the point where specific plant groups dissolve and you see an overall blending of plants.

To understand what intermingling is we start by looking at what it is not. Intermingling differs strongly from garden traditions embodied in the work of renowned designers such as Gertrude Jekyll and Roberto Burle Marx. They used plants to create bold, broad colors in the garden. Closer to home, our parents and grandparents trimmed yews into boxes and hydrangeas into tidy circles. This type of garden design focuses on clear edges or borders between plants and at its core, it is visually tidy and organized.

Adopting an intermingled approach to planting design requires a different perspective. Rather than valuing a crisp and static aesthetic, intermingled plantings attempt to heighten the sensual effects of natural plant communities. Because these gardens are naturalistic and wild in appearance, people often assume that they are easy to achieve and successfully maintain. Such perceptions are, unfortunately, false. Intermingled planting schemes can be easier to maintain long-term, but they require careful design for continued success.

To date, easy guides to planning intermingled plantings are not available for home gardeners. However, by considering four factors that affect the success of an intermingled planting, you will be well on your way to a flourishing naturalistic garden strategy. These four aspects are site conditions, culture, plant habit and aesthetics.

The first step is understanding how environmental factors of the site will affect your proposed planting. Wild plants shift in shape over time in response to environmental factors. A rich and successful intermingled planting requires detailed observations of site conditions and a sensitive design for plants that thrive in those conditions. While you may not have a tall grass prairie nearby to study, a stroll around your local natural preserve should offer ample inspiration to inform your own naturalistic planting.

Besides site conditions, maintenance frequency and skill dramatically affect the success of intermingled planting schemes. It’s easy for a home gardener to spend 30 minutes a week selectively removing a few plants that have overrun other plants. If a site is to be maintained by commercial labor, it’s essential to plan for potentially less diligent and consistent care.

When I lived in Umbria, I was amazed at the incredible diversity of species that thrive in the rural hay meadows that were completely mowed down in spring and fall. Within each square foot of ground, you could easily pick out six to ten species of annuals and bulbs. The centuries-old cultivation tradition opened space for these small forbs to reseed themselves in different patterns each year, resulting in incredible diversity and color. With a little care and attention, any North American gardener can establish similarly diverse communities in their own back garden.

In addition to the environmental and cultural factors of the site, the growth habits of individual plants are a significant aspect of intermingled planting schemes. Many gardeners have discovered the danger of planting a vigorously romping mugwort (Artemisia lactiflora), for example, next to species with slower growth rates. Such considerations are important enough in traditional garden design, with tidy edges between groups of different species. They are even more important when plant groupings are designed to blend into each other. Couple mugwort with an equally thuggish partner, such as joe pye weed (Eutrochium purpureum), and you’ll be smiling. Many temperate climate plants change shape and size dramatically over the course of their lives, and even over the course of the seasons. These changes have to be accounted for if an intermingled planting scheme is not to disappoint.

The final, but most personal and entertaining, aspect of designing an intermingled planting scheme is the potential for memorable aesthetic effects. Aesthetics considers the basic notions of scale, color, harmony and depth. When planned carefully, intermingling offers the opportunity for greater richness than would be possible with a more straightforward planting scheme. Think of the difference between a coloring book page, with its clear blocks of defined color, and a Pissarro or Monet painting with its flickering color and light.

One of my first experiences of an intermingled planting was of Jason Delaney’s phenomenal bulb plantings at Missouri Botanical Garden. Within a formal framework of yew hedges and traditional spring bulb groupings, he intermingled different colored cultivars to achieve memorable richness and depth. One particularly strong combination was a blend of two hyacinth cultivars, the bright coral pink ‘Gypsy Queen’ and the deep pink-violet ‘Woodstock’. Either color, clumped on its own, would have been a bit dull. Together, the colors blended into a tapestry of unforgettable richness.

Others may be flying to visit trendy European garden shows or hiring the latest popular designer in order to experience the richness and spontaneity of an intermingled planting. But with a bit of attention to site conditions, culture, plant habit and aesthetics you can be well on the way to a memorable intermingled home garden design of your very own.

Caleb Melchior is a Missouri-born landscape architect based on Florida’s west coast. Subscribe to Horticulture to read more articles like this one from Caleb and other expert garden designers.