[CANUFNET] Medians

[Alison Bond]

Ian,

In Collingwood (zone 5a...in southern Ontario's snowbelt) we find that
perennials tolerate snow better than shrubs as they don't get crushed.
We've tried Rosa rugosa, False Spirea, and Gro Low Fragrant Sumac with no
luck.  Karl Foerster Feather Reed Grass has been extremely successful in a
1m median (irrigated) and curbside planting beds (not irrigated.)  It is cut
once a year in the early spring (cool season grass that greens up early) so
we have the benefit of the grass in the fall/winter.

As for trees, we had moderate luck with honeylocust in a 1m x 1m x 1m tree
vault (the road engineers designed the vaults and we came in afterwards to
'green things up.'  Covering the canopies with burlap over winter (not an
easy job) improved the survival rate.  The ones that survived their first
year seem to be doing (relatively) well 4 years later.

Inspired by the Quebec City Urban Forestry Conference tours, we recently
tried planting one of the Dutch Elm Disease resistant elm cultivars in a
boulevard (zone 4.)  After the first winter there was 100% survival for the
elms and serviceberry (A. canadensis), if you can believe it.  Honeylocust
was third.  Red oak (native to the area) did terribly.  We don't know if it
was stock from a warmer seed zone or if the red oak is just not able to
tolerate that much salt and snow (trees were often buried in 2m snowbanks.)
Anyway, I'd try the elm in in a median if I were planting trees.

Finally, I've noticed that if trees are tall enough to have some of the
canopy above the salt spray, they seem to pull through.  We planted four
freemani maples in a boulevard.  As you may know, they grow almost too fast
and the stock at planting was very tall.  The lower canopy was killed off by
the salt but the rest of the canopy seems to be doing OK...again about 4
years later.

Alison

Alison Bond OALA CSLA
Landscape Architect and Certified Arborist
Envision-Tatham

On Mon, Mar 23, 2009 at 4:48 PM, Ian Wilson <IWilson at kelowna.ca> wrote:

>  I'm looking for information on low-maintenance plant materials and
> landscaping designs for road or highway medians that have "stood the test of
> time".  I just got a copy of the new "Planning the Urban Forest" book and
> saw a photo of an interesting median planting in Urbana, Illinois utilizing
> native plants, which got me thinking about what other cities might be using
> for medians.
>
> The City of Kelowna has been developing more medians in recent years.
> We've tried a variety of different designs and plant materials.  Medians
> seem to be among the most difficult growing sites in terms of maintenance
> and plant health.  Here's some of the challenges that we have had:
>
> 1)  Getting enough soil volume for trees and plants, particularly in
> narrower medians
> 2)  Salt spray due to winter road maintenance in our climate.  Some trees
> suffer bud dieback due to salt spray.  Others might suffer soil toxicity
> once the salts get too high.  One of the best trees we've found so far seems
> to be red oak.
> 3)  Sand accumulations in the planting bed.  Even if you have a nicely
> mulched bed, after a year or two it all ends up looking like a bed of sand.
> 4)  Worker safety in order to maintain median plant materials and remove
> garbage and maintain irrigation etc.
> 5)  Landscaping medians on highways with higher speeds - the additional
> wind and salt spray etc seems to be particularly hard on plants when the
> traffic speeds are higher.
>
> We have several different designs that we have tried, depending on
> situation.  We're starting to move towards a couple of different designs,
> one is more of a xeriscape design with trees in a large planting bed and
> xeriscape plant ground covers (where we have the space).  Where speeds are
> higher and sand and salt accumulation is an issue we're trying more
> hardscape with trees in "pits" and hard surfacing, but unless we use Silva
> cells or something similar we run into the challenge of limited soil
> volumes.
>
> Anybody have some good designs or ideas that they'd like to share?
>
> thanks, Ian
>
>  Ian Wilson, RPF, Certified Arborist
> Park Services Manager
> City of Kelowna
> Park Services
> Civic Operations
> 1359 KLO road,
> Kelowna, BC  V1W 3N8
> iwilson at kelowna.ca
> Phone: (250) 469-8842
> Fax:  (250) 862-3335
>
> [image: BestBlooming]
>
>
>
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