Category Archives: Perennials

Old Concepts, New Technology, Sustainable Results

Growing plants on rooftops is not a new concept. Centuries ago northern Scandinavians harvested sod from their surrounding landscape and placed it upon structures to create effective insulating and water resistant roof systems.  The Vikings who explored the upper Atlantic built grass-covered homes where they settled and in Iceland sod roofs and walls have been used for hundreds of years.

Although the living roof or green roof has been in use for a long time, modern green roof technology has helped to elevate this building method from a crudely effective construction element to an aesthetically pleasing, ecologically responsible building solution for age-old building problems and current environmental concerns.

green roof or living roof is a roof of a building or other structure that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.

Green roofs can be very basic, known as extensive green roofs that incorporate drought-tolerant, self-seeding native ground covers such as sedums, grasses, mosses and prairie flowers that require little or no irrigation, fertilization or maintenance. These green roofs are lightweight, inexpensive, and can be retrofitted onto existing buildings, often without significant alterations or additional structural support.

Intensive green roofs are more elaborate roof gardens designed for human interaction. They generally have a relatively flat roof surface or mild slope and allow for a larger selection of plants, including shrubs and trees and require specific engineering to be able to conform to the weight load requirements.

Today, the green roof is gaining in popularity as an environmentally conscious architectural expression that is a viable element of any sustainable landscape management plan; and here is why:

  • Storm-water runoff will be greatly decreased with the utilization of a living roof. The growing medium and the vegetation of a green roof retain large amounts of storm water and release it back into the environment. A typical green roof can absorb 30% of the rainwater that falls on it, reducing the amount of water that goes through our waste water systems.
  • It is a common misassumption that a green roof system will have a deleterious effect on the integrity of the roof system. Quite the opposite.  A well designed, correctly installed green roof will protect the waterproof membrane that lies beneath it and, in turn, will extend the overall life of a roof.  Recent studies indicate an increase in life span of almost double.
  • Green roofs absorb carbon dioxide that contributes to global warming; and the slow transpiration of water back into the air creates a cooling effect that helps reduce the heat retention and emanation in and around your building.
  • In addition to the energy saving features described above, the actual mass and density of a living roof will provide excellent sound insulation for a building as well.
  • And let’s not forget the aesthetic benefits of the rooftop garden. The roof garden intermingles the pre-construction environment with the built environment creating a sustainable cooperation between development and nature.  People love to interact in the relative secluded natural setting created by the intensive garden on a rooftop space.  Additionally, they benefit emotionally and psychologically from the ability to even look upon the greenery of an intensive or an extensive roof top garden.

Green roof technology was re-invented in Germany in the mid-20th century and quickly spread throughout Europe mainly due to its restorative environmental impact.

Today, Chicago has been a leader in green roof installations with up to 7 million square feet on approximately 500 rooftops; the most of any city in the United States.  The benefits of the green roof have not been ignored by suburban businesses and multi-family residential buildings either.

Green roofs add beauty, sustainability and longevity to buildings

Corporations, commercial building owners, and homeowners associations are looking for solutions to increase employee well-being, decrease their carbon footprints, increase their LEEDS scores, and differentiate their properties from their competition.  The rooftop garden has proven to be just such a solution.

Reach out to ILT Vignocchi today to inquire about the potential for your headquarters, office building, clubhouse, or other structure to benefit from a green roof installation.

Favorite plant series: Amsonia tabernaemontana ‘Blue Ice’

During a meeting discussing seasonal color displays, when phones were set on vibrate and the focus of our discussions was solely about plants, I was reminded how passionate and opinionated our staff is when it comes to what they love the most.

I decided it was important to celebrate that our employees each have their favorite species and that those favorites tend to change and evolve.  Hence our favorite plant series.  First up might as well be me, Donna Vignocchi Zych.

Easy and carefree, ‘Blue Star’ is an outstanding long blooming selection. I look forward to several weeks of deep, glacial blue blooms on this compact, shrubby-like plant. It forms a mound of green, willow-like leaves, bearing clusters of interesting dark blue buds that open into dainty, star-shaped, medium blue flowers from late spring into early summer. The dark green, compact foliage remains attractive all summer and forms the perfect backdrop, for colorful annuals and bold perennials. In fall, the willowy foliage turns a rich shade of yellow complementing my favorite fall blooming perennials: sedum, hardy mums and purpled-leaved heuchera, to name a few.

Light: Full sun to part shade

Soil: Well-Drained

Height: 12-18”

Spread: 12-18”

Growth Habit: Dense, Mound, Shrub-like

Uses: Specimen, edging, or massed in perennial or mixed shrub borders

Problems: No serious insect or disease problems.

Companion Plants: Sedum, Allium, Blue Hosta, Purple-leaved Heucheras

Dark blue buds open to ice blue blooms

Dark blue buds open to ice blue blooms

Amsonia spring blooms

Spring blooms and neat dark green foliage

Amsonia fall foliage

Dark green foliage turns to golden yellow in fall


Geranium ‘Rozanne’

Tried and Trouble-free!

Year-after-year, ‘Rozanne’ continues to be a “rock star” in my garden!

I highly recommended ‘Rozanne’ for larger flowers than others of its type along with an extended bloom period and vigorous, yet dense, habit. The lovely saucer-shaped flowers are deep violet-blue with a white throat and darker venation. Attractive, faintly marbled, deep green leaves change to a brownish red in late fall for added interest. With a semi-vining habit, ‘Rozanne’ weaves gracefully through my garden, filling in any gaps along the way, allowing for its companion plants (see below) to flow together in a stunning blend of colors and textures.The non-stop show begins in June and lasts till frost.

Light: Full Sun to Part Shade

Soil: Well-Drained

Height: 1 to 3 ft.

Spread: 1 to 3 ft.

Growth Habit: Clumps, Spreads

Uses: Perennial beds, borders, also excellent for massing or in mixed containers.

Companion Plants: Coreopsis, Asclepias, Calamintha, Salvia, to name a few.  For more information about other fun geraniums, click here.

Semi-vining habit

Semi-vining habit

Close up of flower

Close up of flower

Fall color

Fall color