A Better Way to Protect Trees and Pedestrians

Safe Path permeable product replaces cast iron tree grate

Safe Path permeable product replaces cast iron tree grate

Through a business acquaintance, I had the good fortune to meet with Mr. Christian Rodriguez, a company representative from Blue Drop, Inc.  We met at a downtown San Diego street intersection where Blue Drop, Inc. had a contract with the City of San Diego to replace old cast iron tree grates with their new product called Safe Path.

Tree planters within pedestrian sidewalks are typically small confined spaces surrounded by concrete with lots of pedestrian traffic.  Tree grates were installed around the planter pit primarily to protect people from tripping over tree roots.  The grate also allowed watering to occur beneath the grate and afforded the tree a degree of root protection from pedestrian traffic.

When first installed surrounding a young tree, there is plenty of room for the tree trunk and root collar to grow and expand.  Tree grate openings typically are up to 12″ in diameter.

Tree trunk lifts grate creating potential trip and fall hazard

Tree trunk lifts grate creating potential trip and fall hazard

A young tree with a two inch diameter trunk will add one inch of trunk diameter per year. The tree will outgrow the tree grate opening within a decade.  Just as the tree reaches maturity and is starting to provide the maximum intended benefits,  the trunk begins to lift the tree grate.  Either the tree or tree grate must be replaced.

When I met Mr. Rodriguez, he showed me a downtown site where Blue Drop had installed their new Safe Path product.  The product is a poured in place permeable rubberized material that levels the planter surface with the adjacent sidewalk.  Water quickly infiltrates the permeable product which allows for both water and gas exchange.  The tree trunk, root collar and any surface roots are safely protected by the product.  As the trunk and roots enlarge, the products cracks, allowing for easy product removal and mending.

Pedestrians safely travel over Safe Path tree system

Pedestrians safely travel over Safe Path tree system. Photo by Blue Drop

Because Safe Path is poured in place, it appears to be an ideal product to retrofit existing planter systems and especially for irregular shaped planter areas.  The product provides a smooth, yet permeable surface, creating a safe environment for pedestrians while protecting tree roots and enhancing street scene aesthetics

I have no financial of special interest in Blue Drop Inc or any of their products.  As a certified arborist who has provided expert witness testimony in trip and fall cases involving trees, I was interested in discovering new technologies that improve public safety around trees.

Click the link to read the full article reviewing the product. A Better Way to Protect Trees and Pedestrians

 

Can a Tree Capture Particulate Matter from the Air?

For years, certified arborists and urban foresters have learned the many benefits of trees. Energy savings are one of the foremost known benefits of trees as they shade building during the summer reducing the need for air conditioning and deciduous tress allow sunlight to reach structures during winter months, solar radiation decreasing the need for winter heating.

Another known benefit for trees are their ability to reduce storm water runoff and erosion, particularly during the winter months. Tree root systems bind soil particles and slow storm runoff from roofs and other impervious surfaces, trees act as bio filters, slowing storm and irrigation water runoff and allowing the water time to slowly percolate into the soil profile rather than run off into the street or storm drain system.  By forcing water to pass through the soil profile, rather than runoff into storm drain systems, the soil mass filters impurities before the water enters into streams, ponds and aquifers.

Birch Tree planting works as filter

A Birch street tree planting used for testing as a green filter to remove particulate matter from the air we breath

Continue reading “Can a Tree Capture Particulate Matter from the Air?” »

Going it Alone?

What happened to life in the Golden state? The economy is slamming us all and the ongoing drought and water restrictions have caused many stressed property owners, home owner associations, property management companies, builders and developers to reduce or eliminate landscape design, construction, renovation and maintenance budgets. This is unfortunate timing as now is time to invest in sustainable landscape systems, we need to renovate old turf oriented water guzzling landscapes with better adapted, sustainable landscape with improved irrigation technologies.

For those who have taken landscape design, construction, renovation and maintenance issues into their own hands, beware you may easily make incorrect decisions that might ultimately cost you more money than consulting with a landscape professional.

I published an article that provides simple landscape and horticultural design tips for those trying to go it on their own.

The article discusses a process called Horticultural design as an alternative to traditional landscape design. This process uses plants cultural requirements matched to the specific site environment to determine the planting palette. Use this process to maximize plant establishment, vigor and vitality, reduce water consumption, insect and disease problems and reduce maintenance costs.

Use Horticultural Design to Enhance and Simplify Your Landscape

What a challenging time for property owners faced with landscape design and renovation projects in California. Aside from a difficult economic environment, the ongoing drought and mandated reduction in water delivery from Northern California and the Colorado River has deeply impacted landscape design, construction and maintenance practices throughout California, particularly in the central and southern part of the state. Sustainability is now a common buzzword in the landscape industry, however getting there is proving far more difficult than imagined.

Looking back at projects designed and constructed in the 80’s, 90’s and early 2000, there has been significant improvement and increased awareness in landscape plant and soil materials and dramatic improvements in irrigation technology. Growers and nurseries have introduced thousands of improved plant species, varieties and hybrids, improving traits such as disease and insect resistance, drought resistance, flower size, color, duration, and so much more

Older plant varieties such as Delosperma alba “Disneyland” (white ice plant) that had terrible root rot problems have been replaced with hardy, drought tolerant plants such as Baccharis and Myoporum ground covers. Hibiscus shrubs, loved for their flowers but highly susceptible to giant white fly and aphids, have been phased out, same with other shrubs that had disease problems such as Fireblight on Carissa (natal plum). Fast growing Eucalyptus species are declining with structural deficiencies due to repeated psyllid insect infestations, root rot, age and inappropriate use. Thousands of trees pose a major threat and hazard to property owners and the general public.

As water availability diminishes, rates will continue to increase, rationing is most likely a permanent fact of life. We are faced with major changes and decisions on how to create affordable, sustainable landscape development for single, multi-family housing, commercial and industrial sites, public and recreational facilities.

Homeowners, HOA’s, property managers and businesses face a tremendous challenge in making the correct decisions how to design or renovate new or existing landscape systems. With so many facets to consider, it is easy to become overwhelmed and loose site of the original goal, concept or objective in a landscape project. Landscape architects are design professionals whose expertise is a recommended resource. However, we are all struggling to make ends meet, budgets for landscape professional services are very limited and many businesses, property owners, HOA’s and property managers are faced with trying to go it alone or limited professional design and consulting to assist.

In response to questions from friends and clients, the following provide an alternative to the traditional landscape design process by simplifying landscape planting and design decisions during the planning stage, utilizing a process called horticultural design.

Horticultural Design

The term horticultural design is the process of creating a plant palette based on the compatibility of plant’s cultural requirements with the site environment. Don’t select a theme then try to force plants to work in an environment they are not adapted or suited to. Knowing plants cultural requirements is fundamental for horticultural design and plant selection.

Here are some basic cultural requirements to look for when determining a plant palette:

  • Sunlight exposure
  • Size at maturity
  • Hardiness to frost or exposure to heat
  • Climatic zone.
  • Water and drainage requirements.
  • Soil type and preference.
  • Resistance or tolerance to pests and disease
  • Environmental micro-climates, winds, salt air, pollution
  • Flower showiness
  • Foliage showiness
  • Fruit showiness
  • Attract bees, hummingbirds
  • Use: Accent, foundation, understory, foreground, hedge, screen
  • Plant origin, native to where

SITE ANALYSIS:

In order to select plants that are best suited to your location, perform a thorough site analysis of the property; take pictures to document site conditions. The success of horticultural design relies on selecting plant material adapted to site conditions. The site analysis should confirm:

  1. Sunlight, shade and part shade exposure.
  2. Existing trees, shrubs, fences, walls, etc.
  3. Footprint of the residence within the site.
  4. Location of utilities such as water, gas, electric, telephone, CATV.
  5. View corridors and screen/privacy requirements.
  6. Grade/drainage conditions.
  7. Above and below grade obstructions.
  8. Dimensions and area requirements of the site.

A complete site analysis may include drafting a plot or site plan. A scaled plot plan is useful for organizing your thoughts and design concepts. The plan should show the confines of the property, footprint of the house, driveway and other flatwork, hardscape or masonry. Use the drawing as a template, then overlay sketch paper to try different ideas or concepts.

PLANT CULTURAL REQUIREMENTS:

A plant palette is developed once the site analysis is completed. Using the cultural requirements, select plants appropriate to the conditions in the site analysis, consider:

  1. Sunlight exposure and geographic area to start the process. South, southwest, and west exposure are for full sun plants. East, southeast, and northwest exposures are for part sun part shade plants. North is strictly full shade plants.
  2. Size at maturity is often overlooked, resulting in serious relocation or maintenance expense down the road. Understand the full height and width of the plant and plan appropriately.
  3. Make sure the plant can tolerate the heat or cold extremes of the site. Succulents, citrus, avocado, and many tropical or sub-tropical plants cannot tolerate a hard frost; understand the hardiness rating of the plant.
  4. In conjunction with the hardiness rating is the geographic zone rating where your site is located. The geographic zone rating is based on the climatic influences and temperature extremes. Plants that flourish in a Midwest climatic zone may not perform will in a Southern California climatic zone.
  5. Understand the soil type you plan on landscaping or gardening. Clay soils drain poorly, hold water and create root rot problems. Sandy soils drain quickly but lack organic content and nutrients. Know whether the plant likes wet or dry soil conditions. Soil structure, drainage, aeration and nutrient content can be improved with soil amendments and fertilizers.
  6. Drainage, often overlooked, is one of the most important aspects for a successful garden or landscape. Make sure the site maintains a 1-2% surface gradient away from structures. Provide sub-surface drainage systems as required to avoid saturated conditions.
  7. Avoid plant genus and species that have disease or pest problems. Select newer improved hybrid species and cultivars that are disease and insect resistant.
  8. Inspect your site for microclimates, exposure to a prevailing wind condition (Santa Ana’s in Southern California), salt-water exposure from coastal wind, pollution from adjacent heavy traffic.

DESIGN CONSIDERATIONS:

Some simple, basic design considerations include:

  1. Accent or hi-light plants, usually a tree(s).
  2. Foundation or background shrubs to anchor the landscape.
  3. Understory, foreground shrubs and perennials.
  4. Ground covers, annuals and perennials for borders, accents, foliage and flower color.
  5. Existing site home, building or office architecture and finish surfaces. Select plant material that will enhance existing site features.
  6. Grade changes, retaining walls and site elements to create movement and interest.
  7. Pathways, including D.G., sidewalks, pavers, bricks etc.
  8. Entertainment areas, BBQ, outdoor kitchens and bars.
  9. Water features, objects d’ art.
  10. Utilitarian uses such as doggie run area, trash storage, and pool equipment.
  11. Exterior site lighting, many fantastic low voltage lighting options for hi-lighting, safety and security.
  12. State of the art automatic low volume “smart” irrigation system for efficient distribution and maximum water cost savings.

PRACTICAL CONSIDERATIONS:

  1. Group tree and shrub planting based on sun exposure. Never mix plants with different sun exposures i.e.: full sun with full shade plant.
  2. Layer plantings based on height and size requirements.
  3. Repeat planting patterns to reinforce the plant theme.
  4. Avoid using too many different plants. Don’t attempt to create a botanic garden.
  5. Avoid using too many different flatwork and hardscape finishes. Select finish surfaces that compliment and enhance existing structures or features, do not introduce foreign finishes that detract from the property.
  6. Create separate irrigation zones for turf versus planter areas, shade versus sun exposure area.
  7. Make sure the grading and drainage create a favorable growing condition.
  8. Avoid standing water on pathways.
  9. Avoid land locked planters or install sub-surface drainage in the planter.
  10. Remember that an effective, efficient, beautiful design for a garden or landscape is usually based on simplicity and repetition to reinforce an effective theme.

CASE STUDY:

The front yard of this estate has a full sun exposure with a very hot microclimate. The raised bed planter had no drainage outlets or sub-surface drainage system, the soil was very moist exhibiting anaerobic respiration and root rot. Existing Betula alba trees (European White Birch), were declining due to excess heat and root problems, leading to borer insect damage. The Carissa (natal plum) shrub in far right background mounded to 5’, covering windows and showing symptoms of fireblight. An ancient Boxwood hedge served no purpose other than hiding the plants behind. The large urns at the front entry contain an old Bougainvillea.

By removing the hedge, the entire planter area became visible and usable. Sub-surface drainage system removed excess moisture previously accumulating in the raised planter bed. Hi-light trees included Agonis flexuosa “After Dark” and Magnolia grandiflora “Little Gem”, trees adapted to full sun exposure, with contrasting foliage color and textures, complimented the architectural building style and color.

Foundation shrubs include Leptospermum scoparium “Ruby Glow” (tea shrub), and Duranta repens, (Sky flower), foreground shrub is Callistemon viminalis“Little John”. Notice the improved, colorful walkway entry to the side yard; previously it was all turf grass. High volume irrigation spray heads were retrofitted with low volume nozzles, cutting irrigation water up to 50%

Renovated landscape with new accent trees and natural theme

Below is a backyard hi-light, or what can be seen of this very cool fountain. Unfortunately, the existing rear yard hedge used to provide privacy had engulfed the fountain. Poor maintenance shearing techniques turning shrubs into geometric shapes destroying what should be a beautiful, informal hi-light viewing area. The wonderful planter urns had been neglected and provided little color or interest. This was a challenging area because it faces south and receives full sun exposure, however the upper-story tree hedge provided mixed partial shade. The goal was to enhance the prominence of the fountain and design an informal, colorful, relaxing area.

Is there a fountain back there?

Below is the same fountain however the large tree hedge limbs have been pruned to open the sight line corridor to the fountain while still retaining screening for privacy. Cercis canadensis “Forest Pansy” (Eastern Redbud) tress frame the fountain while providing breathtaking spring flower color, followed by ever-changing foliage color throughout the summer and fall. The existing urns were replanted with Abutilon hybrid shrubs as the anchor, surrounded with annual and perennial color. All the plant materials were selected for a full sun exposure, a particular size, effect, foliage or flower color or other special effect specific to the site.

Fountain hilight with Cercis Redbud trees

With so much to consider, the design process can be a significant hurdle for novices and those going it alone. Try to keep things simple. Start by going to a local nursery, preferably a wholesale growing grounds that has a large selection of trees and shrubs from one gallon to 60” boxed trees. Take pictures and make notes about the plants you like. Research your findings; the Sunset Garden book is an excellent resource for understanding plants and their cultural requirements.

In summary, selecting plants based on their cultural requirements that are adapted to your site will determine the theme for the landscape rather than the traditional method of having a landscape design that arbitrarily imposes an artificial landscape theme. The plants will thrive, establish quicker, use less water, and have fewer insect and disease problems, ultimately providing a less costly footprint with improved sustainability. With fine-tuning, the plant palette can be refined to suit any particular theme, coordinate and enhance site architecture, color, or specific features. Using an artificially designed landscape that does not suit the site with incompatible plant material will establish slowing, poorly, have disease and insect problems, lack vitality, consume more water and have far greater maintenance and renovation costs.

Even with the suggestions contained within this article, plant selection and the design process requires knowledge, research and creativity. Jeremy Rappoport is a professional horticulturist, C-27 licensed landscape contractor and certified arborist. For over two decades, Mr. Rappoport teamed with prominent public and private master development companies and community homebuilders as a land development specialist, with postings as a landscape, grading and offsite superintendent, purchasing agent, manager of sales, bidding and estimating, Director of Operations and Director of Land Development.

Mr. Rappoport combines his extensive work experience, professional degree and industry certifications providing landscape, horticulture, arboriculture and site development consulting, design and expert witness services. For more information, contact Jeremy Rappoport at 858-205-4748.