Parking Lot Landscape Islands, what is the best approach?

[Jason T. Radice]

Interesting…the excuse I always hear is that the trees in the islands act to shade the parking lot to reduce the heat island effect. Yea…right. You would need a real canopy for that to happen, not twigs placed at 50′ on center. Besides, just how often are the trees allowed to grow? Overzealous landscapers tend to make them into lollypops. I know…I know, this is done to prevent overhang to reduce liability. Well, just make the islands bigger and get rid of the narrow green strips and sidewalks in the middle of the parking lots nobody uses! An island should be a minimum 6′, preferably the width of a parking space (too keep spacing even).

 

Some had sugested soil volume? Bingo! There are a number of ways to do that; structural soils (eww), root trenches, and my favorite… Silva Cells. I have yet to find a client to buy into them (almost had one, then the project got canned…stupid economy), but they seem like a great idea can can kill many birds with one stone. http://www.deeproot.com/products/silva-cell/silva-cell-overview.html

[Jason T. Radice]

I’ve got a collection started, too. My favorite is the sprinkler system on when it is pouring rain. And I’m getting more. I’ve hit the motherlode in upstate NY…where design goes to die.

[Brett T. Long]

http://land8lounge.com/photo/diy-center/next?context=user   This was a simple, integrated stormwater and native habitat restoration that revitalized a commercial lot.  Design capacity is a twenty year storm event infiltration as required by the regional planning agency.  Removed 13,000 sf of asphalt from a car lot and cut in bio-swales from the existing 120,000 sf of AC.  We had 280″ of snow this past year and only lost (3) 15 gallon Aspen that were planted a little too low in one of the bio-swales and were under water until July.  Thet he plants and trees are thriving. The client didn’t want to pay for flush concrete curbs, but the AC edges are holding up pretty well as the AC is 6″over 8″.

[James Couillard]

What kind of difficulties are you finding with rain gardens in small parking lot islands?  And what is small?  200sf?  400sf?

 

[James Couillard]

May I reprint this picture please?

[James Couillard]

Please see http://hort.ifas.ufl.edu/pubs/abstracts/efg/efg9605.shtm regarding root barriers. 

 

and http://hort.ufl.edu/woody/spacing.shtml about spacing, which is great by the way.

 

and lastly, http://miami-dade.ifas.ufl.edu/pdfs/disaster/Hurricane%20Preparation%20files/Where%20to%20put%20the%20money,%20the%20tree%20or%20the%20hole.pdf.

 

They are all great resources.  This is a great topic.  Islands can be tough.

[Mike G]

Go for it.  Fraxinus americana if you’re looking for the species.

[Thomas J. Johnson]

Trees, rain gardens (where appropriate, IE around the perimeter so the plows can push snow into them during the winter… raised islands in the middle, so the plows won’t dig up your plants), massing of grasses/sedges… low hardy ground covers… If you do rocks, do river stones 3-4″ min… wood mulch is becoming outdated and the good stuff is environmentally unsound…
Shrubs always look abused… because they are…
People are going to want to cut across the islands. Anticipate this and make a path, so they don’t make one for you… I don’t know why no one ever does this but you always see broken shrubs, trampled ground cover and dirt paths haphazardly cut through the islands…
That’s about all I’ve got to say about parking lot islands…

[Andrew Garulay, RLA]

Curious about good mulch being environmentally unsound.

 

[Jason T. Radice]

Many (well most I deal with) commercial developers will not allow any type of gravel or rock mulch be used in the landscaping for a number of reasons. One, if it is too fine and escapes the bed/curb, it can become a liability from being a tripping hazard. Two, it can be a real pain to keep neat and to weed. Third, if it is large, it can be used for nefarious purposes…projectile, childs plaything, window/door opener. Lastly, gravel in the wrong installation can draw out soil moisture, not keep it in.

[Thomas J. Johnson]

Cedar – not good trees to cut down… especially for the sole purpose of shredding and spreading…

Pine is ugly and breaks down quickly… acidic?

The mixed stuff from municipalities isn’t worth mentioning…

The dyed stuff is best reserved for miniature golf courses…

Cocoa shells are cool (sustainable) but tend to float away…

The best stuff I’ve seen is Black Forest which is triple shredded and fairly decomposed. It’s dark, consistent and contributes to the soil composition pretty quickly.

[Thomas J. Johnson]

yeah, yeah, yeah… and wood mulch needs to be reapplied every year, encourages fungus/mold/insects, has a tendency to float away when it rains, looks like 1980 and the good stuff is not so good for the environment… It’s an imperfect world…

[Andrew Garulay, RLA]

Real pine/spruce/hemlock BARK mulch is not bad at all and looks fine as it breaks down. The problem is that it can no longer be found because it is always mixed with recycled wood. It used to be the norm, but this is one of the negative sides of the “green revolution” – recycled crap is added to everything to make more money and hide behind the “green curtain” (can I trademark that?)

[Jordan Lockman]

Mulch in general is okay for the soil. In my area we tend to have really alkaline soil so acidity is a bonus, though you would be surprised how little evergreen litter actually acidifies the soil. In general lime is the alkaline agent and organic matter of all kinds is slightly acidic so no matter what you add you are adding to the acidity of the soil. 

The thing that makes mulch bad for the environment is the fact that we are cutting and shredding trees solely for the purpose of spreading them out in  a 4″ blanket over our plantings. Also the dyes cant be great or at the least not trusted and the same goes for the recycled mulch. 

[Jordan Lockman]

Don’t forget about the mold and blob that forms on Cocoa shells. Not healthy for animals either.

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