The Matrix Planting Approach to Garden Design

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Gardens walk a fine line between nature and design. They’re composed of natural elements, yet they’re inherently artificial. Most of us have learned gardening involves first clearing the land, then amending the soil and finally choosing and placing plants based on aesthetics. Then we do everything we can to keep that aesthetic the same.

In contrast, wild spaces like meadows and woodlands manage themselves. The picture is everchanging as the plants and other organisms slowly adapt to shifting conditions.

Chicago's Lurie Garden at Millenium Park, designed by Piet Oudolf, is one example of matrix planting, in which compatible perennials and grasses are closely planted to cover the soil and share resources. Seasonal elements like spring-flowering bulbs embellish the design.

A design approach gaining momentum worldwide aims for nature to do a lot more of the heavy lifting in the garden, and even some of the designing. Eschewing amendments and power tools, it’s based on an elegantly simple principle: to garden more like nature does.

Referred to as matrix planting, wildscaping, modular planting and new perennial or new American style, gardens following this philosophy often depend on self-sowers. Plants are left standing through the winter, and there’s an overall freer aesthetic than that in traditional garden design.

The Background of Matrix Planting

The concept was born when German city planners sought to plant large areas of parkland after World War II in a reproducible way that would need minimal maintenance. The planners created planting mixes and formulas that could be used modularly. In a matrix, plants with similar cultural needs are grouped so that they will knit together above and below ground, forming a cooperative ecosystem that conserves water and discourages weeds.

The High Line in New York City also uses matrix planting.

Dutch plantsman and designer Piet Oudolf’s gardens popularized this style, adding artistic flourish to the formulas while playing with color and form, embracing four-season interest and catering to wildlife. Beautiful year-round, they invite you to enjoy the smallest detail, from the sound of grasses in the breeze to the sculpture of ghostly seed heads.

It takes a lot of thought to look this natural. While matrix gardens appear wild, they are meticulously planned, with cultural needs the first consideration. Led by the concept of “right plant, right place,” they match plants that enjoy the same soil, sun, moisture and weather conditions, and arrange them according to their patterns of growth.

The benefits are substantial for both gardener and planet. With human inputs drastically reduced, the garden’s ecology can flourish. Established matrix plantings should not need the life support we give most gardens: fertilizer, dividing, supplemental watering.

Compared to traditional garden plots, they improve carbon sequestration, reduce stormwater runoff, and boost habitat and biodiversity “exponentially,” said designer Benjamin Vogt, the man behind Monarch Gardens, a Nebraska design firm devoted to this style of gardening.

The Basics of Matrix Planting

“Matrix gardening is about having a set starting point and letting nature find its way,” said Vogt, author of Prairie Up: An Introduction to Natural Garden Design.

“I think a lot of the matrix planting is about shifting gardeners’ attitudes to planting much tighter together and stopping with the wood mulch,” Vogt said. “Mulch keeps (gardens) in a permanent establishment phase—not letting the plant set seed and make a matrix of roots that will be resilient to climate and weed pressure.”

Matrix planting relies on a foundation of shallow-rooted grasses plus deeper-rooted perennials.

In the wild plant communities that inspire Vogt and likeminded designers’ work, there are dozens of plant species in each square yard, a density that creates resilience. If one plant dies, there are ten others who can take over its functions in the system.

Typically, the matrix layer in a garden includes a foundation of sedges (Carex) or other shallow-rooted grasses or groundcovers appropriate for the site conditions. (Read all about sedges here.) Tap-rooted plants, whose roots furrow deep into the earth, are paired with plants that use only the upper layers of soil. The module, or combination, can be any size, and it can be repeated organically or in patterns. The designer chooses a ratio of sedges/grasses to flowering forbs, selecting plants that will play well together without competing too much. Each species’ rate and pattern of growth and how it reproduces must be considered. With the matrix decided, the designer then adds in structural plants, like trees and shrubs, plus seasonal highlights.

The research just may be the most intense part of the process, said Vogt: “The most important thing you do is selecting the plants before you grow them.”

A Simple Approach to Matrix Planting

Thomas Rainer, principal of the Virginia-based landscape architecture firm Phyto Studio, noted, “One could glaze over with the complexity” of choosing compatible plants. But, happily, there are simple ways to enjoy the benefits of matrix planting in your home garden.

“The continuity that the matrix has makes it very applicable to smaller spaces,” Rainer said. “It can be as simple as a combination of two or three things.”

We can boil the process down: Choose plants that suit your site’s conditions, whose growth patterns complement each other, plant them tightly, surround them by groundcover.

To dip your toe into matrix planting, Rainer said, try it as a lawn replacement where your turf is dying out under shade trees. Or, if you have a bed with a few structural perennials and shrubs, start by adding groundcovers to conserve water and shade out weeds. Blue grama (Bouteloua gracilis), prairie dropseed (Sporobolus heterolepis), and Sesleria are common choices for sunny sites, while Carex species are a great choice for partial shade. (Check with nurseries and extension offices for the best local options.) To save money, buy a few plants and divide them over time.

Benjamin Vogt suggests a 50-50 grasses-to-forbs ratio as a starting point, but it depends on the goal of the planting. Some go as far as 80-20. Rainer notes the more matrix-dominant the planting, the more restful the scene will be visually. Seasonal themes, with shifting flower and color interest, add drama, but “that drama is often at the expense of stability” and can leave a void if you tip the scale too far.

Since matrix gardens rely on close planting, they are usually planted with plugs instead of quart- or gallon-sized pots. Getting the garden established can take a year or two, being alert to water the small plants and stop perennial weeds before they can take hold. Annual weeds will likely be shaded out the second year. After that, the main work for the gardener may be to thin out an overly successful group, replace a structural plant and move or cull excessive seedlings.

Matrix Planting in Diverse Spaces

While matrix gardens are best known for popularizing the plants of the American prairie, the principles translate to all kinds of plants and settings. Tony Spencer, who studied with Piet Oudolf, blogs about naturalistic design at The New Perennialist. Inspired by gardens like Oudolf’s Hummelo and Hermannshof botanical garden in Germany, he has been employing matrix concepts in his Canadian garden that includes shady hillsides and a woodland pond.

“The concept works very well for a lot of different habitats,” he said.

The pond area demanded a part-sun to shade combination needing average to moist, but not wet, soil. Spencer struck upon two main seasonal teams. Fragrant Phlox divaricata ‘Blue Moon’ and Tiarella wheryii bloom together in spring, while the fronds of maidenhair fern (Adiantum pedantum) are emerging. Later, the mature ferns provide a backdrop to the white flowers of woodland aster (Eurybia divaricatus ‘Eastern Star’). Each of these four plants make up close to 25 percent of the planting, with a few ‘Lady in Red’ ferns Athyrium angustum f. rubellum and Uvularia scattered throughout to “add flow.”

“I have three different matrices through this area. They’re not meant to be simple,” he says, “but the feeling is very natural. People who visit say it’s hard to tell what’s designed and what is not.”

And while wild landscapes and celebrated public gardens may provide inspiration, you can create your naturalistic garden despite limited acreage. Even one raised bed or a parking strip humming with pollinators can make a strong impact.

“If you just have small square footage, why not have something that takes you away mentally to another place?” said Rainer. “To have a small corner where you have those moments, it’s magic. It’s transformative.”

Read three ways to help your neighbors accept matrix planting design, which can stick out amid traditional landscaping.