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Trees & Shrubs

Caring for Evergreens

 

Evergreens are highly valued in landscaping because of their year round colour and interest. 

Preparing the Soil

Evergreens prefer a moist, well-drained soil that is rich in organic matter. When preparing a site for evergreens loosen up the surface of the soil and add some organic matter (compost / manure). This will allow tender roots to grow into loose soil.

Planting

Plant containerized evergreens anytime from spring through fall.  Spring is a great time to plant as you get the best selection and it allows plants to establish before the onset of winter.

General Rules for planting:
  • have a soil mix ready for backfill that contains existing soil mixed with compost or manure at a ratio of 3 parts existing soil to 1 part compost or manure
  • make sure tree or shrub is planted at the same depth as it was in the container
  • pack firmly to eliminate air pockets
  • water well after planting and use a transplant fertilizer (10-52-10)
  • newly planted evergreens should be thoroughly watered frequently

Watering

Since evergreens retain their foliage year round, they are constantly losing moisture through their needles.  Moisture loss is the number one killer of evergreens and usually isen’t noticed until early spring when plants start to break dormancy.  Therefore watering plays an important role ensuring evergreens thrive and survive Calgary's volatile climate.

All evergreens require water regularly white becoming established; the first two years are crucial.  Newly planted stock needs to be watered frequently and thoroughly.  What this mean?  A general guideline is a deep watering twice a week, and more often during hot weather.  Place a hose at the base of the tree on a slow trickle for 20 to 45 minutes; this will ensure the root ball and surrounding soil has enough water available to support plant growth and establish a deep, strong, root system.  Monitor new plants and if at any time the root ball feels dry, water deeply using a slow trickle.  It is especially important to water evergreen thoroughly in the spring, in the fall, and during periods of drought.

Fertilizing

Soil contains all the nutrients plants need to grow and thrive; unfortunately soils may not have nutrients in sufficient quantities to suit each plant's needs.  It is advisable to add 5-7.5cm (2-3 inches) of organic matter on an annual basis this will help add nutrients to the soil.  Plants also benefit greatly from regular applications of fertilizer.

New Plants: It is strongly recommended to use a starter fertilizer at the time of planting for all new transplants.  Choose a fertilizer that is high in phosphorous, such as 10-52-10, will encourage the development of a strong root system which is necessary for healthy growth and production.  It will also help prevent transplant shock.  You can continue to use this fertilizer throughout the first growing season.

Established Plants: There are a variety of fertilizer formulations available for established plants.  Regular applications throughout the growing season are recommended, following label directions.  Stop fertilizing at the end of July, late summer or fall fertilizing may stimulate new growth at a time of year when plants should be hardening off and preparing for the winter.

Pruning

Evergreens generally don't require much pruning except corrective pruning to remove dead, damaged or diseased branches.  If the leader is damaged or broken, it can be removed and one of the top lateral branches should be tied up immediately to form a new leader.

Dwarf, rounded, and columnar evergreens may need to be lightly sheared to re-shape.  To create a bushier, dense tree pinch back up to ½ of the new growth after the new candles have elongated but before new needles have opened out. 

Preventing Winter Injury

Chinooks can cause added stress to evergreens during the long winter months.  There are certain things you can do to prevent damage from drying winds and warm temperatures.

  • use hardy plant varieties
  • do not apply fertilizer after August 1
  • water thoroughly in the fall, watering with a slow trickle for 1 hour per tree to ensure they freeze deep and won't dehydrate over the winter
  • use anti-desiccant sprays in the fall to prevent moisture loss from needles
  • add a layer of mulch around the base of plants will help keep moisture in the soil
  • winter protection for tender evergreens or evergreens planted in exposed sites.  Build a burlap screen on the south and west sides of the plant, this will shade plants and prevent excessive moisture loss to winds

Damage to Foliage (browning needles)

There are a number of reasons for needles on evergreens to change colour.  

  1. Autumn Needle shed - loss of older needles towards the inside of the tree is a natural process. Evergreen needle shed is a gradual process, but there are occasions when many needles will discolour simultaneously and drop.  Any factors that increase stress on evergreens with intensify autumn needle shed.
  2. Winter colour - Some varieties of evergreens naturally change colour as temperatures drop.
  3. Spring Frost Injury - late spring frosts can severely injure or kill new emerging growth.  New growth droops, turns brown and dies.
  4. Herbicide Damage - improper or careless application of herbicides can result in minor distortion to complete defoliation (death)
  5. Drought Damage - most evergreens are shallow rooted - very sensitive to moisture depleted soils.  Needles gradually turn yellowish, and then light brown starting at the top of the tree working down, and from the inside out.  Water plants thoroughly and frequently to prevent needle loss.
  6. Animal Damage - dog urine dicolours needles and rabbits, mice, deer may feed on bark
  7. Salt injury - salt spray from roads or excess salt in soils
  8. Nutrient deficiencies - Iron chlorosis is common with our alkaline soils.  Use an evergreen fertilizer that contains micro-nutrients

**note browning of needles is commonly caused by environmental conditions not insects or diseases.
Winter injury includes desiccation (drying), sunscald and cold temperature damage.  The main symptom is discoloration of needles on previously healthy plants. 

NAME  HEIGHT SPREAD ZONE FOLIAGE EXPOSURE FEATURES

FIR - DWARF BALSAM

Abies balsamea Nana                        

 1-2'  

30-60cm

                

 3-4'

90-120cm          

3

dark green

sun or shade 

small rounded flat topped plant with  short flat aromatic dark green leaves

JUNIPER - Chinese

Juniperus chinensis

3-10'

1-3m

5-8'

1.5-2.5m

3-4 varies based on variety   full sun to light shade conical tree to spreading shrub with sharp pointed needle-like leaves

JUNIPER - Common

Juniperus communis

 1-5'

0.3-1.5m

 2-7'

0.6-2m

2-3 varies based on variety full sun to light shade spreading shrub to small columnar tree; spine with white band along leaves

JUNIPER - Creeping

Juniperus horizontalis

4-24"

10-60cm

3-10'

1-3m

2-3 varies based on variety full sun to light shade low growing, prostrate, creeping shrub with soft textured feathery leaves

JUNIPER - Savin

Juniperus sabina

1-4'

0.3-1.2m

5-8'

1.5-2.5m 

3 varies based on variety full sun to light shade spreading shrub with a dense, layered branching habit

JUNIPER - Rocky Mountain

Juniperus scopulorum

5-16'

1.5-5m 

3-10'

1-3m

3-4 varies based on variety full sun to light shade dense, upright, pyramidal tree with sharp pointy foliage

JUNIPER - Squamata

Juniperus squamata

1-2'

30-60cm

4'

120cm

3-4 varies based on variety full sun to light shade slow growing dense, rounded shrub with star-shaped sharp foliage

JUNIPER - Eastern Red Cedar

Juniperus virginiana

 13-16'

4-5m

3-7'

1-2m

3-4 varies based on variety full sun to light shade columnar to broadly pyramidal in habit; sharp pointed needle-like leaves

LARCH - Weeping

Larix decidua Pendula 

13-16'

4-5m

7-10'

2-3m

3 green turning yellow in the fall full sun to part shade graceful weeping tree with an irregular habit; tolerates wet soil and windy sites

LARCH - Siberian

Larix sibirica

40-50'

12-15m

10-23'

3-7m

2 green turning yellow in the fall full sun to part shade broad pyramidal tree with arching branches and soft needles, fast growing

CYPRESS - Russian

Microbiota decussata 

1½-2½'

45-75cm

6-8'

1.8-2.4m

2 bright green sun or shade low growing, flat topped shrub with arching branches; shade tolerant

SPRUCE - Bird's Nest

Picea abies Nidiformis

1½-2'

45-60cm

3-5'

1-1.5m

3 light green full sun to part shade unique, flat-topped (nest-shaped) dwarf with light green needles

SPRUCE - Christina Norway

Picea abies Christina

23-26'

7-8m

3½-5½'

1.1-1.5m

3 dark green full sun to part shade columnar tree with short green needles; hardy tree great for small spaces

SPRUCE - Dwarf Norway

Picea abies Pumila

3'

90cm

4-5'

1.2-1.5m

2 bright green full sun to part shade dense, globe-shaped shrub with bright green needles; resistant to winter burn

SPRUCE - Little Gem

Picea abies Little Gem

1½'

45cm

1½-3'

45-90cm

2 dark green full sun to part shade compact, dwarf, flat-topped shrub; very dense dark green needles

SPRUCE - Pyramidal Norway

Picea abies Fastigiata

20-30'

6-9m

4-8'

1.2-2.4m

3 dark green full sun to part shade very narrow, upright columnar tree; great for small spaces

SPRUCE - Weeping Norway

Picea abies Pendula

7'

2m

10'

3m

3 dark green full sun weeping tree with long narrow slightly twisted branches; size varies depending on training

SPRUCE - White

Picea glauca

66'

20m

16'

5m

3 dark green full sun large broadly pyramidal native tree

SPRUCE - Baby Blue Eyes

Picea pungens Baby Blue Eyes

16'

5m 

10'

3m

3 blue full sun to part shade compact, slow growing pyramidal tree one of the bluest spruce

SPRUCE - Bakeri

Picea pungens Bakeri

16-20'

5-6m

10'

3m

2 powder blue full sun to part shade compact, slow growing pyramidal tree with powder-blue needles

SPRUCE - Colorado

Picea pungens

60-66'

18-20m

26'

8m

2 green to blue full sun to part shade hardy, large pyramidal tree with sharp needles in shades of green and blue

SPRUCE - Columnar

Picea pungens Fastigiata

16-20'

5-6m

7'

2m 

3 silvery-blue full sun to part shade narrow upright columnar spruce with silvery-blue needles

SPRUCE - Fat Albert

Picea pungens Fat Albert

33'

10m

16-20'

5-6m

3 intense blue full sun to part shade dense pyramidal shape with sharp intense blue needles

SPRUCE - Globe Blue

Picea pungens Glauca Globosa

4-6'

1.2-1.8m

4-6'

1.2-1.8m

3 silvery-blue full sun to part shade dwarf globe-shaped shrub with silvery-blue needles

SPRUCE - Montgomery

Picea pungens Montgomery

7-10'

2-3m

7'

2m

3 blue full sun to part shade compact, globe-shaped shrub that forms a leader becoming more upright

PINE - Bristlecone

Pinus aristata 

13'

4m

7'

2m

2 dark green with white flecks full sun to part shade irregular dense conical tree with upturned branches; dark green white flecked needles

PINE - Swiss Stone

Pinus cembra 

33-40'

10-12m 

13-20'

4-6m

3 dark green full sun to part shade dense, narrow pyramidal tree; soft dark green needles and smooth bark

PINE - Lodgepole

Pinus contorta var latifolia

 40'

12m

10-16'

3-5m

2 dark green full sun to part shade a slender native pine with an open branching habit and smooth bark

PINE - Limber

Pinus flexilis

33'

10m

16'

5m

2 blue-green full sun to part shade a broad pyramidal tree that becomes rounded with age; soft, twisted blue-green needles, adaptable, resistant to wind burn

PINE - Columnar Mugo 

Pinus mugo Columnaris

7-10'

2-3m

3-4'

1-1.2m

2 dark green full sun to part shade very narrow upright pine, dark green needles, small cones, orange-red bark

PINE - Dwarf Mugo

Pinus mugo pumilio

4-5'

1.2-1.5m

5-7'

1.5-2m

2 dark green full sun to part shade dense, low growing shrub with dark green needles; annual pruning to keep smaller

PINE - Mops Mugo

Pinus mugo Mops

2-3'

60-90cm

2-3'

60-90cm

3 dark green full sun to part shade dwarf dense uniformly rounded shrub with dense needles; no shearing required

PINE - Mugo

Pinus mugo mugus

7-13'

2-4m

7-10'

2-3m

2 dark green full sun to part shade dense upright mounded shrub with short green needles; annual pruning for shaping

PINE - Slowmound Mugo

Pinus mugo Slowmound

2-3'

60-90cm

3'

90cm

2 dark green full sun to part shade dense low globe-shaped shrub with tight dark green needles, no shearing required

PINE - Tannenbaum Mugo

Pinus mugo Tannenbaum

10-13'

3-4m

5-7'

1.5-2m

2 dark green full sun to part shade compact pyramidal pine with dense dark green needles; low maintenance

PINE - Austrian

Pinus nigra

40-50'

12-15m 

16-26'

5-8m

4 dark green full sun to part shade dense pyramidal tree with spreading branches, furrowed bark, and long needles

PINE - Ponderosa

Pinus ponderosa

40-50'

12-15m

16-20'

5-8m

4 dark green full sun to part shade an irregular pyramidal tree with long dark green needles and furrowed orange-brown bark

PINE - Scotch

Pinus sylvestris 

40-50'

12-15m

16-26'

5-8m

3 bluish-green full sun to part shade low maintenance broad pyramidal tree, furrowed orange bark, twisted needles

PINE - Columnar Scotch

Pinus sylvestris Fastigiata 

20'

6m

4'

1.2m

2 bluish-green full sun to part shade dense upright columnar tree with twisted needles and orange peeling bark

PINE - Dwarf Blue Scotch 

Pinus sylvestris Glauca Nana

3-6'

1-1.8m

4-6'

1.2-1.8m

3 bluish-green full sun to part shade dense round globe-shaped shrub with pointed bright blue-green needles

PINE - Mountain Pine

Pinus uncinata

13'

4m

7'

2m

3 dark green full sun to part shade upright pyramidal tree with dark green needles and dark brown cones

YEW - Hick's

Taxus x media Hicksii

10-13'

3-4m

3-4m

0.9-1.2m

3 dark green sun or shade narrow, upright shrub with dense dark green needles and red berries (poisonous)

YEW - Morden

Taxus cuspidate Morden

3-4'

1-1.2m

4-5'

1.2-1.5m

3 dark green sun or shade slow growing spreading shrub with dense green needles and red berries (poisonous)

CEDARS

Thuja occidentalis

2-13'

0.6-4m

2-7'

0.6-2m

3-4 green full sun to part shade Cedars require moist soil and a sheltered site protected from winds and hot sun