Matrix planting

In 2023 we renovated a 72 ft. long garden bed and amended the clay soil with compost. The plan was to plant mostly natives and near-natives that were appropriate for clay soil and full to part-sun conditions. I also wanted to incorporate a matrix planting design which would give the bed a looser aesthetic than a traditional garden border. Matrix planting mimics the plants in nature, but they are meticulously planned. I am deeply inspired by the Dutch gardener Piet Oudolf and his garden design philosophy. I began to read everything I could and watch every video that I could find. I find his garden designs are compelling and deeply emotional. He often leaves the seedheads of spent plants standing in the winter to great effect. I also agree with his comment that “brown is a color”. 

Matrix planting is a garden design concept that consists of low growing, shallow rooted grasses that are distributed in a grid like pattern with taller, deeper-rooted plants that rise above the ground layer. The tall plants create drama when done well. Plants are placed close together and become knitted together in a tight community above and below ground. This community creates an ecosystem that discourages weeds while conserving water and sharing resources. Plants are selected with similar cultural needs so they don’t outcompete each other. Carex (sedges) are commonly used as the ground cover layer. In my garden, I am using Sporobolus heterolepis (prairie dropseed) and Allium lusitanicum (allium summer beauty) for my ground layer. 

The concept of matrix planting originates from post WWII Germany when large parklands were planted. The plantings were often block patterns with huge swaths of plant material, planted close together and required minimal maintenance. Oudolf, a leading figure of the “New Perennial” movement, made matrix planting popular with his many designs including Chicago’s Lurie Garden at Millenium Park and NYC’s High Line. He chooses plants with four season interest and structure, leaving plants standing throughout the winter for its aesthetic beauty and for wildlife. Roy Diblik, plantsman and perennial garden designer has worked with Piet Oudolf in the Lurie Garden installation and is just as inspiring. Diblik is the author of “The Know Maintenance Perennial Garden” book. His educational garden design lessons can also be found on YouTube. 

Besides the visual appeal there are many other benefits to this style of planting. Planting plants in close proximity improves carbon sequestration and reduces store water runoff and increases habitat and biodiversity. The need for fertilization is reduced because perennial plants are getting everything they need from the soil itself. Planting plants tighter together reduces the need for mulch because plants become the mulch. Matrix planting attracts pollinators and is naturally pest resistant. The soil also increases in fertility as these plantings are cut back in late winter and the plant material is left behind on the soil to break down naturally (otherwise known as the chop and drop).  

Designers choose to use plugs in most matrix garden installations. Plugs establish faster. Most beds take a year or two to mature. You can use annual plants to fill any empty spots in the bed. Weeding is needed until plants fill in. If you feel the need mulch while you are waiting for your beds to mature, try the free leaf mulch at the transfer station. Leaf mulch is a good choice, as it breaks down into the soil faster. 

Planting in this style does require some assessment and fine tuning. Some perennials self-seed and some are short-lived. Get to know the growth rate and growth habit of the plants you choose. Choose plants with different bloom times so there is always some food around for the pollinators. Know your site’s conditions before you begin. Start with a small, select plant list that is suitable to your site and purchase in multiples. Matrix gardening looks naturalistic and appears wild but is highly controlled.

Oudolf’s philosophy is that a garden is a dynamic entity, evolving and transforming throughout the season. The garden’s beauty extends beyond its vibrant flowers. The entire lifecycle is beautiful, including its decay.

Photo: A matrix planting designed by Piet Oudolf at NYC’s High Line. Credit: J. Clark