Grouping Plantings: The Case for Clustering 🌻
A cluster of sedge. A drift of river oats. A clump of cardinal flower. A grouping of goldenrod.
Planting in groups is a very common practice in the gardening world. But it doesn’t always come intuitively. When you first start gardening, many of us have had this common experience: get one or two of everything and spread it out evenly. Not necessarily wrong, but the further you delve into gardening you’ll find advice on grouped planting. Traditional landscapers abide by these rules too, so why exactly are we all doing this?
Firstly… Aesthetics
This is why you’ll see native gardeners and traditional landscapers alike grouping plants. A single flower is a specimen, singled out. When you get to grouping you have your plants merge into the space as a shape. One grand visual unit, rather than scattered individuals. Odd numbers (3, 5, 7, 9) are used because they prevent a type of symmetry which can feel rigid. Odd numbers also let you pick a center point and then build out from there on both sides.
Secondly… Ecological Benefit
Let’s place ourselves in the proverbial shoes of a little bee for a moment. You’re out and about and discover an enticing single bloom or two. After a brief moment harvesting, you’re back to the search. Later, you find a long drift of blooms. Your forage becomes simplified and your wings are working less to get from flower to flower. You’ve entered your bee flow state. This study found that grouping the same plant species together increases visitation rates and keeps pollinators in one place longer. Of course, this isn’t a case against diversity, rather a point about what efficient foraging is for a pollinator. Plant diversity is valuable in the landscape, but remember that planting in large clusters will likely entice visitors more.
Thirdly… Practicality
Grouping plants also accomplishes something we always harp on… low maintenance. Dense, clustered plantings tend to shade soil more effectively, suppress weeds, and hold moisture longer. Less watering, less mulching, and less weeding. As a baseline, 12-24” is a decent starting point for spacing perennial herbaceous plants. Closer to 12” if you want to reduce edges and create a clump faster. Lastly, look into purchasing perennial plug trays online (e.g. Prairie Moon Nursery) if you want to establish a drift with a little more bang for your buck.