Landscape Rehabilitation
A Twelve-Step Program to a Sustainable Landscape
Recommendations in seminar
 Apply to trees and shrubs (the backbone of permanent landscape)
 Are based on current plant and soil science for urban gardens
Roadmap





Understanding urban landscapes
Analyzing and preparing landscape site
Choosing appropriate and healthy plants
Installing shrubs and trees correctly
Maintaining landscapes sustainably
Step 1: Accept that problems exist
 Urban soils are not natural soils
 Ornamental landscapes are not agricultural fields
 Improper landscape management = poor plant health
Step 2: Analyze landscape conditions first
 Temperature, light, moisture gradients
 Seasonal changes
 What kinds of plants do well?
Soil analysis
 Soil tests required – http://www.umass.edu/soiltest/
 Texture? Moisture dynamics? Compaction? Organic matter? Minerals?
Soil hydration
 Poor drainage  flooding
 Poor retention  drought
Compaction
 Feet, vehicles, machinery and rainfall all compact soil
 Compaction  water and air movement   root movement
Urban soil fertility
 OM issues – how much is present?
 pH issues – acid or alkaline?
 Nutrient issues – what’s missing?
Step 3: Choose appropriate plants
 Consider both native and non-native, non-invasive species
 Consider mature sizes of trees and shrubs
Myth: Native plants are always the best choice for environmentally sustainable
landscaping
Fact: Many native plants cannot tolerate urban conditions
What is mature size?
 Depends on genetics
 Depends on local climate
 Depends on microclimate




Step 4: Select healthy plants
Are plants properly maintained (water, fertilizer, appropriately sized containers)?
Can you see the root flare? (good)
Are there surface roots? (bad)
Have the crowns been topped? (bad)
Step 5: Prepare soil
 Don’t dig a hole
 Don’t amend with organic matter (unless your soil is less than 5% OM by volume)
Myth: Adding high levels of organic amendment improves soil
Fact: Soil amendment temporarily increases drainage and reduces compaction, but
over time heavily amended soils are more vulnerable to subsidence and compaction,
and can lead to nutrient overload
Evidence of organic overload




Step 6: Remove all materials around roots
Remove all foreign materials
Remove container media or clay from B&B
Keep roots moist at all times
Bare-rooting improves root establishment by removing barriers
Myth: Root balls must be left intact during transplanting
Fact: Removing potting mix or clay from root ball:
…eliminates barriers
…allows for root correction
…ensures planting at grade
…enhances root growth
Step 7: Prepare and correct roots
 Prune excessively long roots
 Correct root defects
 Keep roots moist at all times
Step 8: Dig a hole to fit the roots
 Dig a shallow hole as deep as the root system and twice as wide
 In the center, form a soil mound to support the root crown
 Remove weeds and large stones




Step 9: Install plants properly
Arrange the roots radially over the mound
Be sure root crown is at or above grade
Backfill with the same soil that came out of the hole. DO NOT AMEND
Water in, adding more soil as holes develop – don’t press or step on soil
Step 10: Use coarse organic mulch
 Mulch will protect soil and reduces competition from turf and weeds
 Use at least 4” of mulch up to, but not touching, the trunk
 Do not use sheet mulches (including fabrics, plastic, cardboard)
Myth: Landscape fabric provides permanent weed control
Fact: Landscape fabric reduces water and air transport, interferes with plant root
health, and does not stop weeds
Benefits of organic mulches





Slow release of nutrients
Improve soil structure
Enhance plant establishment
Enhance beneficial soil microbes
Enhance diversity of soil animals




Step 11: Maintain sustainably
Add a nitrogen fertilizer (no phosphorus) as a top dressing
Water your tree well during the first year of establishment, especially if you’ve
removed roots or are planting during hotter seasons
Do not crown prune during root establishment. You will know your roots have
established when leaf flush occurs
Don’t waste money on transplant amendments
Myth: Phosphate fertilizer stimulates root growth
Fact: Excess phosphate destroys symbiotic fungi, interferes with nutrient uptake,
contaminates soil and aquatic systems
Myth: Transplanted plants should have their crowns pruned to compensate for
reduced root mass
Fact: Crown pruning redirects plant resources away from roots and towards new
shoot development
Step 12: Don’t be an enabler
 Stake low and loose
 Remove staking after one year
 Dig up and replant anything that cannot support itself
Myth: Newly planted trees must be firmly staked
Fact: Overstaked trees don’t develop taper and are more likely to snap after release





Final thoughts
Know your site, and your soils, before you add anything
Anticipate how your landscape plants and soils will change over many years – not
months
Realize that improper management practices cause more plant mortality than any
other environmental stress
Understand that plant and soil management practices need to be sustainable
Don’t look for gardening miracles in a bag, bottle or box
For more information:
Dr. Linda Chalker-Scott,
WSU Associate Professor and Extension Urban Horticulturist
Email: lindacs@wsu.edu
Webpage: http://www.theinformedgardener.com;
Blog: http://www.gardenprofessors.com
Books: http://www.sustainablelandscapesandgardens.com