2. Plant Spacing
Not to be confused with plant scale, plant spacing refers to the specific widths and heights of fully-grown plants and how they interact with other plants located in close proximity. Have you ever driven by a commercial property and noticed all the green meatball shrubs dotted throughout the beds? A landscape like this seems way too vacant. While maintenance plays a role in this situation, a planting design with appropriate spacing would have resulted in a more visually satisfying landscape. Not to mention, spacing plants too far apart gives room for weeds to grow and choke out the desired plants.
Meatball shrubs in their natural habitat.
On the other end of the spectrum, when plants are spaced too close together they can overcrowd and compete with each other for water and nutrients. Overcrowding can also lead to poor airflow amongst the plant life, which can quickly lead to many different diseases. Also, overcrowding various species of plants creates a chaotic design where the more aggressive species outcompete the others.
Small evergreen plants such as Helleri Holly and Inkberry are best used as a continuous hedge or massed in groups. Some plants work well individually or in groups. A shrub like Brandywine Viburnum or a tree such as Serviceberry are both examples of plants that work well alone or in grouped together. As I wrote in the previous post in this series, it is important to consider the backdrop for the plants before making decisions. Sometimes it is appropriate to space plants in such a way that they stand out individually. For example, placing a single tall, narrow evergreen such as Emerald Green Arborvitae at the corners of a tall structure creates a pleasant visual balance.
An area where improper plant spacing runs rampant (even among professional landscapers and designers) is with groundcovers and perennials. In order for a groundcover planting to be effective, the plants have to be spaced in such a way that there are no gaps in-between the plants. While it is acceptable under certain circumstances to space rapid growing groundcovers such as Vinca farther apart as a strategy for saving money on nursery stock, using the same approach with a plant that spreads more slowly like Purple Coneflower will give undesirable results. With perennials and groundcovers the aim is to either to form a continuous massed planting or to have a mixture where one species spills into the next one.
The Lurie Garden at Chicago's Millennium Park provides a good example of perennials attractively spilling into one another. A planting design by Piet Oudolf.
Image Source: millenniumparkfoundation.org
When making decisions on spacing plants, it is also important to consider the style of the landscape. A more formal landscape could benefit from utilizing plants that are spaced at a greater distance from one another for a particular affect (like with the boxwoods in the first photo below), or by placing the plants closer together to form a parterre—as in the second photo below from the Atlanta Botanical Garden. A plant's natural form must be considered as well because certain plants are narrow from top to bottom while others are naturally wider at the bottom and taper on the way up. A tree like Southern Magnolia typically grows full all the way from the top to the ground, and should not have any plants underneath as this tree will overshadow them.
Consider the context and intention of the landscape before making decisions on plant spacing and maintenance. These boxwoods were spaced this way intentionally.
Image Source: deborahsilver.com
The boxwoods used in this parterre at the Atlanta Botanical Garden were spaced close at time of planting to create the desired effect as quickly as possible.
In conclusion, to use proper spacing, there are characteristics, conditions, and contexts that have to be considered first. There is no one size fits all when it comes to planting design. If you’re looking to install new plantings at your home or business but you’re unsure of which plants to use and how to use them, reach out today to see how Shippey Landscape Architecture can provide you with a professional planting design that utilizes plants to successfully meet your unique design criteria.