Michigan State University Extension
Home Horticulture - 01701524
01/01/96

Blueberry



     The   lowbush  blueberry is the low growing  type  that

grows  wild.   The highbush blueberry is  the  type  usually

planted   in  commercial   plantings.    This    information

applies   to  the highbush blueberry.  Grow  varieties  that

mature   at   different  times  to  prolong   the   harvest.

Blueberries  do  not  need cross  pollination  in  order  to

produce  a  crop.  Some varieties  are:  Bluecrop,  Bluejay,

Rubel and Jersey.                                           


Site                                                        


     Highbush  blueberry needs an average growing season  of

160 days and is badly injured by temperatures of -20 to -25.


     A   loose  soil is best.  A mixture of sand  and   peat

gives  excellent   results.   Heavier  textured  soils   are

suitable  if acidic and high in organic matter.  Peat  soils

may  stimulate late   growth  that  fails to  harden  before

winter    or   such  soils  are  often  in  frost   pockets.

Blueberries  must have an acid  soil  with  a pH  between  4

and  5.1.   The  pH  can   be lowered with  applications  of

sulfur.   If the pH is very high it  may  not be   practical

to   try   to lower the   pH.    A soil   with   a  constant

moisture  supply  is  best.   The  water  table   should  be

within 14 to 22 inches of the soil  surface most of the time

but good surface drainage is needed.                        


     Good   air  drainage  reduces frost  injury  and  helps

control  diseases.    Problem  weeds  should  be  controlled

before  the blueberries are planted.  Unless a home gardener

has  almost ideal conditions for blueberries it may be  wise

to grow some other fruit.                                   


Planting                                                    


     The   best planting stock is 2 or 3 years old.   The  3

year  old   stock  usually costs more.  Avoid  stock   older

than   3 years.   The  best planting time is  early  spring.

Set   the  plants  4  feet  apart in rows  10  feet   apart.

The   plants should  be set about 2 inches deeper than  they

were  growing in the nursery.  Mix a shovelful of acid  peat

into  each hole at  planting  time if the soil is sandy  and

low  in  organic matter.                                    


Cultivation                                                 


     Blueberries are shallow rooted so cultivation should be

no  deeper   than 2 to 3 inches.  A cover crop may  be  sown

after harvest.                                              


Mulching                                                    


     Most  organic  materials may be used but  they   should

be   allowed  to  weather  before  being  applied   to   the

blueberries.  The  mulch should be about 6 to 8 inches deep.

Double  the amount  of nitrogen applied until the mulch  has

decomposed.   Leguminous  mulches such as clover or  soybean

vines  may  be harmful.                                     


Fertilizer                                                  


     Avoid   using  nitrate forms of nitrogen  and  chloride

forms  of   potassium.   The nitrate and  chloride  may   be

toxic  to blueberries.   Use a blueberry fertilizer such  as

16-8-8-4.   The   4  refers  to  magnesium.   If   blueberry

fertilizer is  not available use ammonium sulfate or urea.  


     Fertilize    new   plants   about   4    weeks    after

planting.   Sprinkle  the fertilizer thinly about 12  to  18

inches  from the plant crown.                               


     Established   blueberries   are  fertilized  in   April

before growth starts.  Spread the fertilizer evenly and keep

it off wet plants to prevent injury.  A very sandy soil  may

need   a  second  fertilization.   If  so, use 50   to   100

pounds   of  ammonium   sulfate  after  spring  rains.   The

following  chart tells how much fertilizer to use per plant.


         Year in Field                Ounces per Plant      

         1 or 2                       1                     

         3                            1.5                   

         4                            2                     

         5                            3                     

         6                            4                     

         7                            4.5                   

         8 or more                    5                     


     A   foliar  analysis  may  be  helpful  in  identifying

specific nutritional needs.                                 


Pruning                                                     


     Fruit   is  produced  on the previous   seasons   wood.

New  plantings  need no pruning until about the  3rd   year.

Then  prune  during the dormant season to remove  the  small

twiggy growth  near  the base of the plant.  After  the  3rd

year,  remove  dead or injured branches,  fruiting  branches

close   to  the   ground,  spindly bushy  twigs  on   mature

branches,  and older  stems  of low vigor.  Heavier  pruning

gives  larger berries  but fewer of them.  Remove old  black

canes  at  the ground level.                                


Watering                                                    


     Blueberries   need  1  to  2 inches  of  water  at   10

day intervals during dry weather.                           


Harvesting                                                  


     Blueberries   ripen  over a period  of  several  weeks.

Three to  5 pickings are needed to harvest all the  berries.

Pick  only   the ripe berries.  A reddish  tinge  means  the

berry  is not yet ripe.                                     


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