Native Plant Window Boxes: A Year Round Design
- Nuts for Natives
- 2 days ago
- 4 min read
Plant once and enjoy through the year.
Perennial native plants make excellent container plants. Planting window boxes and containers with perennials also stretches your dollars further. Once perennials outgrow containers or you are ready to switch it up, you can plant those out in your garden. Buying and planting annuals is a bit cheaper at first but in the long run, they last only a season. Fill your containers with perennials and you will have plants that come back year after year, whether you keep them in containers or move them into the ground.
Getting a Good Native Plant Window Box Combo
There are two combinations to think of when planting a container. One is the design -- how will it look? The second is whether plants are compatible which really means can they all get along with the same amount of water and will one plant crowd out another?
For the design of your native plant window box to work, the trick is to get a variety of textures, leaf shapes and colors with at least one evergreen to carry through winter. Here there is fine texture, grass like shapes and lobed shaped leaves along with a small evergreen. Colors range from emerald green to lighter greens and a caramels. Flowers are a bonus but the design will succeed based on the variations in foliage because most perennials bloom for limited periods of time.
For watering and growing, this combination of plants has average moisture needs. A few do best with more moisture but none are water loving plants. All can grow in full sun. Likewise, none of these plants are aggressive growers so work well together.
The Native Plants
Blue Eyed Grass
Blue eyed grass (Sisyrinchium angustifolium) is a clumping perennial that blooms in later spring or early summer with tiny blue flowers at the tip of the leaves. It grows best in sun and part shade and moist soils. Planting it in a window box makes it much easier to see and enjoy the delicate flowers and the grassy texture is a plus.
Moss Phlox
Moss phlox (Phlox subulata) is a low growing, creeping perennial that creates a carpet of lavender blooms in spring. There are also white and pink flowered cultivars. This perennial can withstand drier conditions once established. The short spiky texture contrasts with the other plants too.
American Arborvitae
American arborvitae (Thuja occidentalis) is a large evergreen tree native to parts of Canada and parts of the central and eastern United States. There are many cultivars of arborvitae. Most change the foliage color, size or shape of the tree, There are cultivars that create spheres, narrow spiky trees and wider shorter trees. This particular cultivar is called Arborvitae 'Sting'® and grows 15 to 20 feet tall. These are very young plants and will be window box sized only for a year or two more. In the meantime though, the small evergreens add winter interest to these boxes. Arborvitae grow best in full sun and can tolerate part shade. They also grow best in moist soils but tolerate average soils.
Heuchera 'Caramel'
Heuchera 'Caramel' (Heuchera 'Caramel') is one of the many cultivars of heuchera where the color of the foliage of the straight species plant has been altered giving it less ecological value. The color contrast does, though, add immensely to the design of these window boxes. Most sources describe this heuchera as growing best in part to full shade. I have had good luck with this full sun location, likely because the plants get consistent water.
American Alumroot 'Dale's Strain'
This naturally occurring cultivar of American alumroot (Heuchera americana 'Dale's Strain') has really interesting color variation in the leaves ranging from silvers to dark greens and is another plant that is great for window boxes so you can appreciate its beauty.
Native Window Box Care
These plants have all faired well through a variety of weather including cooler than usual temps and drought. A couple of things help. These boxes are the self watering type so they have a reservoir in the bottom that collects excess water that roots can access when needed. They still need regular watering, particularly during dry stretches. During dry stretches and winter months, the evergreen is the most sensitive to lack of water. It has the largest rootball and needs to be regularly watered. I water the evergreen every other day during long stretches of no rain.
With any container, there is always a chance, an evergreen will dry out too much over the winter and not be able to survive. I have had good luck with watering moderately once every two weeks during the winter.
These window boxes are 8 years old and came from Gardener's Supply. They are plastic but I believe the plastic actually helps retain moisture in this full sun location. Typically, experts say for any type of container, regular fertilization is needed as the plants and regular watering will use up the nutrition in the potting mix. I have found with native plants in these boxes, they can go for two years without fertilization. It is certainly likely if I added fertilizer, the plants would grow more vigorously. If I were to fertilize, I would look for an organic, slow release fertilizer. Between the 2nd and 3rd year, I do usually refresh the soil, plant anything that looks like it is struggling out in the garden and replace plants as needed. I have also dug plants up out of the garden and put them in containers like these. As always, your results may differ!
Why create habitat with your window boxes? You just never know what might happen. A few years back, two young birds fledged from a nest in these very window boxes!
Happy Gardening.
