We are all guilty of it – biting off more than we can chew, carving out a sprawling garden area, planting quart-sized perennials 2′ on center and then weeding like crazy for the next three years, realizing the whole time that every time we pull a weed and disturb the soil, six more take it’s place. It’s a grueling evolution – eventually the design matures and the plants fill in and cover the surface with their leaves, and we stop pulling weeds (but cut the occasional interloper down to the ground). In this scenario, even when we select fast growing ground covers and plant them in large drifts under mature trees, we have fallen short of designing a sustainable low-maintenance landscape. This is especially true in suburban settings when the trees around a house are less dense than they would be in a mature forest. Why? Nature abhors a vacuum and there’s one hovering right above that groundcover layer.
Most properties around houses have at least dappled light reaching the ground. Tree and shrub seedlings as well as many herbaceous plants are adapted to reach up above the groundcover layer to make use of that available sunshine. Even if you don’t plan for them to grow they will keep trying because it’s nature’s way of being ultra-efficient, where nothing is wasted. So, we’ve learned that it’s better to swim with the current instead of against it – get that ground surface covered as quickly as possible, using seeds and plugs to shorten the fill-in time, but also densely layer the planting vertically with plants at different heights. This “tight community” of plants makes the best use of available sunlight at multiple heights while shading the ground surface to prevent weed seed germination. The end game is for the mature plants to elbow their way into their respective niches and form a more stable (low-maintenance) landscape. The key to success is knowing the relative competitive abilities of the chosen plants, and designing layers both in space and time.
young meadow with complex layers
The “tight community” principle can be applied to all of your garden spaces, whether they are meadows, woodlands, or margins. I will cover how to create balanced meadow compositions in another post, so let’s focus now on shady areas. I often have clients tell me that they want to remove lawn where it is struggling under their mature trees (hooray), and replace it with a sea of flowering ground covers. That’s great, and I understand the psychology of tidy level planes, but I don’t think we can stop at just the bottom layer – we need knee high plants, waist high plants, and shoulder high plants too. To avoid the “messy” look of a wild co-mingled planting, we can group plants in chunks big enough to create legibility, but not too large that they lose the competitive advantages of being in their respective niche, and then carve clear slicing paths through the space. I discuss these “ribbons of order” in a previous post in you want to see more examples.
Dense Layers at Garden in the Woods
All landscape designs inherently need to be site specific and answer the goals of each client, but sometimes it helps to have a recipe to kickstart the process. Let’s imagine we’re going to design a 300 SF block that can repeat or vary for a 1,000 SF woodland garden. Now if you add up the individual textbook square-foot requirements for each of these plants they would never all fit into 300 SF, but they are very comfortable as a densely vertically layered planting, especially if some are spring ephemerals or bulbs that make room for plants that emerge in June.
So here’s a basic Layered Woodland Garden Recipe I call “3-15-36-75″ – starting from the top down (usually the order in which I place them in a design). Remember – this is very simplified – you might want an even greater number of species, or add a short-lived quick growing species that could be seeded in as a space filler – but it’s a place to start:
- (3) – 3 single small understory trees 10-20′ high (Cercis canadensis, Carpinus caroliniana, Hamamelis virginiana)
- (15) – 3 groups of 5 waist high shrubs 3-5′ high (Fothergilla, Rhododendron prinophyllum, Viburnum dentatum)
- (36) – 3 groups of 12 knee to waist high perennials 12-36″ high (Polygonatum biflorum, Polemonium reptans, Actaea racemosa)
- (75) – 3 groups of 25 groundcovers 3-6″ high (Geranium maculatum, Phlox stolonifera ‘Sherwood Purple’, and Tiarella cordifolia ‘Running Tapestry’)
Specific plant selection depends upon soil type, moisture, light, and existing plants. How they are positioned in the landscape depends upon topography, view frames, and the location of pathways that dissect the block. Infinite variations with a similar principle – that’s what makes design so much fun!
The Secret to a Low-Maintenance Landscape, Seriously.
We are all guilty of it - biting off more than we can chew, carving out a sprawling garden area, planting quart-sized perennials 2’ on center and then weeding like crazy for the next three years, realizing the whole time that every time we pull a weed and disturb the soil, six more take it’s place.