How to Care for evergreens

Evergreens are highly valued plants in the landscape because of their year round colour and interest they provide.  There are different types of evergreens as follows:

  • Pines, spruce and fir have needles
  • Junipers and cedars have scale-like leaves
  • Broadleaf Evergreen – rhododendrons, azaleas

Evergreens are beautiful plants that provide shelter, screen undesirable views, help blanket noise, enhance privacy, reduce air pollution and add property value. These benefits make evergreens a valuable investment, especially with careful selection, planting and long-term care.  At Sunnyside our friendly, knowledgeable staff are here to help you choose the right plant for your site so you will be able to enjoy the splendor that evergreens add for many years.

We install a selection of evergreens from common to unique varieties in our landscapes.  We start bringing in our nursery stock in May and get fresh stock in on a weekly basis until September.  We have something to suit everyone’s needs no matter how green their thumb. 

There are lots of different varieties that are spectacular performers for Vancouver Island, despite how wet it can be.  The work being done with plant breeding is amazing and each year we are inspired by new varieties that have improved hardiness, disease resistance and ornamental attributes.

PLANTING

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

HARDINESS ZONE

Hardiness zone is a geographically defined area in which specific plant life is capable of growing.  It encompasses climatic conditions such as plants ability to withstand minimum temperatures.  Nanaimo is located in zone 6.  We experience a large variance of climatic conditions within the city, depending on where you are located.  You will notice different microclimates within your yard that allows you to grow plants that would otherwise be out of your zone.  It is recommended to use zones as a guideline when selecting plants.  Zones 1, 2 and 3 are ideal candidates for landscapes in Alberta.  Zone 4 evergreens can be seen growing successfully in many different landscape situations; a little extra care may be required.

WATERING

Since evergreens retain their foliage throughout the year, they are constantly losing moisture through needles and leaves.  Moisture loss is the number one killer of evergreens and usually isn’t noticed until early spring when they start to break dormancy.  Not something we need to really worry about on Vancouver Island but good to keep an eye on to ensure our evergreens thrive and survive in Nanaimo’s volatile winters.  

All evergreens require water regularly while becoming established; the first two years are crucial. New stock needs to be watered frequently and thoroughly.  What does 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 20-45 minutes; this will ensure root ball and surrounding soil has enough water available to support 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 evergreens thoroughly in the spring, in the fall and during periods of drought. 

In the early fall, allow the soil to dry slightly so growth slows down in preparation for winter.  Depending on temperatures, watering deeply every 2-3 weeks is ideal.  In the late fall it is extremely important to water everything thoroughly to increase winter survivability.  All plants, especially new ones, need a good drink before the ground freezes; this prevents damage to roots from cold dry, soils which in turn will prevent damage to above ground portions of trees and shrubs.

If the soil around evergreens does dry out at any time through the winter, shallow roots may suffer so adding water could help prevent any stress or damage from occurring.

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 2-3 inches (5-7.5cm) of organic matter on an annual basis will help add nutrients to the soil.  They also benefit greatly from the regular application 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 they should be hardening off and preparing for the winter.

PRUNING

Evergreens generally don’t require much pruning except corrective pruning to remove dead, damage 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 the new needles have opened out.

PREVENTING WINTER INJURY

 There are certain things you can do to prevent damage from drying winds and warm temperatures.

  1. Use hardy varieties
  2. Do not apply fertilizer after August 1
  3. 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
  4. Use anti-desiccant sprays in the fall to prevent moisture loss from needles
  5. Adding a layer of mulch around the base to keep moisture in the soil
  6. Winter protection for tender evergreens or evergreens planted in exposed sites. Build a burlap screen on the south and west sides of the tree, this will shade them 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, than light brown starting at the top of the tree working down, and from the inside out.  Water 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. 

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