Planning/Maintenance/ Activities  

Average  Last  Frost  Dates:  Ellensburg:    11  May  Cle  Elum:    24  May  Prepare   and   prime   irrigation   system   for  summer.  

If   needed,   fertilize   rhododendrons   and   azaleas  with  acid-­‐type  fertilizer  after  they  bloom.      If   established   and   healthy,   their   nutrient   needs  should  be  minimal.  Remove  spent  blossoms.  

Use  a   soil   thermometer   to  help  you  know  when  to  plant  vegetables.  When   the   soil   is   consistently   above   60   degrees,  some  warm  season  vegetables  (beans,  sweet  corn)  can  be  planted  in  late  May.  

Apply  2  to  4  inches  of  mulch  around  plants.  Apply   over  well-­‐watered,  weed   free   soils.    Mulch  discourages   weeds,   conserves   moisture,   and  controls  temperature  Iluctuations  in  soil.  

Stake   tall   and   Eloppy   perennials   (peonies,  delphiniums)  as  they  grow.  

After   the   soil  warms  up   enough   to  activate   soil  microbes,  you  can  apply  organic  fertilizers  such  as  compost,  manure,  Eish  emulsions,  blood  meal  and  bone  meal.    

Pest Monitoring & Management If   unknown   problem   occurs,   contact   Kittitas  County  Master  Gardener  plant   diagnostic   clinic  for  identiEication  and  management  options.    

Manage  weeds  while  they  are  small  and  actively  growing  with  light  cultivation  or  herbicides.  Once  the  weed  has  gone  to  bud,  herbicides  are  less  effective.  

Monitor   aphids   on   Eirs,   roses,   arborvitae,  maples,  strawberries  and  ornamentals.  If  present,  control  options  include  washing  off  with  water,   hand   removal,   beneIicial   insects,   or   using  registered   insecticides   labeled   for   the   problem  plant.    Read  and  follow  all  label  directions  prior  to  using   insecticides.     In   lieu   of   using   registered  insecticides,   promote   natural   enemies   (predators  and   parasitoids   that   eat   or   kill   insects)   a   longer-­‐term  solution  for  insect  control  in  gardens.  

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Leafrolling   worms   may   affect   apples   and  blueberries.  Prune  off  and  destroy  affected  leaves.  

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Spittle   bugs  may   appear   on   ornamental   plants  as  foam  on  stems.    In  most   cases,   they   don't   require  management.   If  desired,   wash   off   with   water   or   use   insecticidal  soap   as   a   contact   spray.   Read   and   follow   label  directions   when   using   insecticides,   including  insecticidal  soap.  Control   cabbage   worms   in   cabbage   and  cauliElower,   12-­‐spotted   cucumber   beetles   in  beans   and   lettuce,   and   maggots   in   radishes.  Control   can   involve  hand   removal,   placing  barrier  screen   over   newly   planted   rows,   or   spraying   or  dusting  with  registered  pesticides,   labeled   for  use  on   the   problem   plant.   Read   and   follow   label  directions  when  using  insecticides.  Tiny  holes  in  foliage  and  shiny,  black  beetles  on  tomato,  beets,  radishes,  and  potato  indicate  Elea  beetle  attack.        Treat   with   Neem,   Bt-­‐s,   or   use   nematodes   for  larvae.   Read   and   follow   label   directions   when  using  insecticides.  Prevent   root   maggots  when   planting   cole   crops  (cabbage,   broccoli,   collards   and   kale)   by   covering  with   row   covers   or   screens,   or   by   applying  appropriate   insecticides.   Read   and   follow   label  directions  when  using  insecticides.  Monitor  rhododendrons,  azaleas,  primroses  and  other   broadleaf   ornamentals   for   adult   root  weevils.      Look  for  fresh  evidence  of  feeding  (notching  at  leaf  edges).  Try  sticky  trap  products  on  plant  trunks  to  trap   adult   weevils.   Protect   against   damaging   the  

bark   by   applying   the   sticky   material   on   a   4-­‐inch  wide   band   of   poly   sheeting   or   burlap   wrapped  around   the   trunk.   Mark   plants   now   and   manage  with  beneIicial  nematodes  when  soil  temperatures  are   above   55   degrees   Fahrenheit.   If   root   weevils  are   a   consistent   problem,   consider   removing  plants  and  choosing  resistant  varieties.  

Control   slugs  with  bait  or   traps  and  by  removing  or  mowing  vegetation  near  garden  plots.  Monitor   blueberry,   raspberry,   strawberry   and  other  plants  that  produce  soft  fruits  and  berries  for  Spotted  Wing  Drosophila  (SWD).      Learn   how   to   monitor   for   SWD   Ilies   and   larval  infestations  in  fruit.  Check  evergreens,   especially   spruces,   for   spider  mites;  treat  as  new  growth  begins.  Place  a  white  sheet  of  paper  under  branch  and  tap  lightly,  looking  for  moving  pin-­‐head  size  spots.  

Lawn

Tackle   lawn  weed  problems  on  warm  days   and  continue  to  mow  regularly.      Weed-­‐n-­‐Feed   products   are   fatal/damaging   to  broadleaf  and  needled  plants  and  trees.    Do  not  use  Weed-­‐n-­‐Feed   near   the   plants   root   zone.     Always  use  weed  killers  according   to   label  directions  and  use   accurate   measurements.     Spot   treat   lawn  weeds   with   broadleaf   weed   killers   rather   than  spraying  the  entire  yard.    

You   can   still   aerate   or   power   rake   an   existing  lawn  and  over-­‐seed  an  old  lawn.  

Start  infrequent  deep  watering  of  lawns.  New   lawns   must   be   watered   daily   until   they  germinate.    Then   it   is   time   to  cut  back  and  water  deeply  but  less  frequently.  

Woody Landscape Plants & Fruit Trees

Prune   spring   Elowering   trees   and   shrubs   after  the  Elowers  fade.  Flowering  almond,  quince,  forsythia,  and  lilac  stay  more   compact   and   bloom   better   with   annual  pruning.    Cut  out  dead  or  broken  branches  and  up  to  one-­‐third  of  older  stalks.    

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Avoid   pruning   oaks   and   elms   during   the  growing   season,   typically   early   April   through  October.  Oak  wilt  and  Dutch  elm  disease  are  spread  by  sap  feeding   insects   carrying   the   disease   from   tree   to  tree.  

WAIT  to  prune  birch,  elm,  maple,  and  walnut  trees  until  late  fall.    Although  harmless,  these  trees  bleed  sap  on  sunny  days.  

Thin   fruits   of   apple   (and   other   fruit   trees   if  needed)  about  3  weeks  after  petal  fall.  Apples  should  be  spaced  on  the  average  of  about  8  inches  apart;  peaches  at  6  inches  apart.     If  a  large  crop   is   set   and   no   thinning   is   practiced,   all   fruit  will  be  small  and  branches  may  break.  

Plant   balled-­‐and-­‐burlapped   or   container  nursery  stock  trees,  and  water  thoroughly.    

Remove   and   destroy   overwintering   bagworms  from  landscape  trees  and  shrubs.  

Prune  evergreens  once  new  growth  has  begun  to  appear.  

If   summer   and   fall   blooming   perennials   have  become   overgrown,   dig   them   up   and   divide  them.    

Flowers, Vegetables and Small Fruit

Sow  hardy  annual  Elowers  outdoors  in  early  May  (sweet   alyssum,   bachelor   buttons,   calendula,  cosmos,   sweet  pears).    Wait   until   after   the   last  frost   and   the   soil   has   warmed   before   planting  tender  annuals  (marigolds,  portulaca,  zinnias).      

Pinch  chrysanthemum  and  annual  Elower  plants  to  keep  them  compact  and  well  branched.  Start  in  the  spring  when  the  new  growth  is  4  to  6  inches  long.  Pinch  all  shoots  and  Ilower  buds  every   two   or   three   weeks   until   late   June;  continuing   longer   will   prevent   Ilower   formation.  

The   plant   will   then   grow   new   shoots   and   Ilower  buds,  and  they’ll  bloom  in  the  fall—right  when  you  most  want  a  little  extra  color  in  your  garden!    

When  selecting  new  roses,  choose  plants  labeled  for  resistance  to  diseases.  Fertilize  roses  and  control  rose  diseases  such  as  mildew  with  a  registered  fungicide.  

Deadhead   spring   bulbs   when   they   are   done  Elowering  to  direct  energy  back  into  bulbs.  Do  not  remove  foliage;  let  it  die  back  naturally.  

Plant  perennials  in  your  garden.  Choose  the  right  plant  for  the  right  location.  Place   mulch   around   your   perennial   bed,   but   no  more  than  two  inches.  

Vegetable  gardens.      Begin  harvesting  early  produce  (asparagus,  lettuce  and  onions  to  thin,  spinach,  and  peas).  

Remove   blossoms   from   newly   set   strawberry  plants.  This  will    allow  better  runner  formation.  

Remove  unwanted   sucker   growth   in   raspberries  when  new  shoots  are  about  a  foot  tall.  

Use  a   soil   thermometer   to  help  you  know  when  to  plant  vegetables.  Wait  until  the  soil  is  consistently  above  70  degrees  to   plant   tomatoes,   squash,   melons,   peppers,   and  eggplant.  

Hill  up  around  potatoes  as  they  grow.  Use  compost,  or  pine  needles,  or  the  like.  

Thin   seedlings   of   earlier   planted   crops   such   as  carrots,   lettuce,   spinach,   and   beets,   as   they  

emerge  to  their  proper  spacing.  Remember   to   add   Nitrogen   as   a   side   dressing   to  plants  that  need  it.  

Start  pumpkins  and  melons  indoors  to  transplant  in  early  June.      

Continue  planting  leafy  greens,  beets  and  carrots  in  small  amounts  for  a  staggered  harvest.  

Continue  planting  seeds  and  transplants  such  as  cauliElower,   cabbage,   Brussels   sprouts ,  artichokes,  lettuce,  squash.  Some   transplants   may   need   protection   if   planted  before  the  last  frost  in  your  area.    

Make   successive   plantings   of   beans   and   sweet  corn  to  extend  the  season  and  harvest.    

As   seedlings   mature   and   transplants   grow,  increase   watering   duration   and   decrease  frequency.      Kittitas   County   is   very   windy   in   Spring   and  Summer,  especially   in  the  afternoon,  so  set   timers  to   come   on   in   early   morning.     This   also   allows  plants   to   dry   out   and   helps   prevent   certain  diseases.    

Begin   to   water   fruit   trees   and   berries   deeply  every  week  rather  than  every  other  week.    Drip  systems  work  well  for  this  on  berries.  

Keep  weeds  out  of  garden  and  berries  by  lightly  cultivating.  Observe  fruit  trees  for  pests.    If   trees   need   treating   this   season,   note   time   ‘till  fruit  ripens.    Do  not  spray  while  bees  are  present.  (See  February  calendar   for  Apples,  Cherries,  Pears,  Plums,  and  Prunes  spray  schedules).      

 

Gardening  in  Kittitas  County  

Gardening  in  Kittitas  County  presents  many  challenges  and  opportunities.    While  there  are  ample  days  of  sunshine  and  nights  that  meet  and  exceed  plants’  chilling  requirements,  there  are  extremes  of  heat  in  the  summer  and  cold  in  the  winter.    Wind  is  a  constant  in  all  parts  of  the  county  and  snow  depth  is  a  factor,  especially  in  the  higher  elevations.    Add  to  this  the  fact  that  Eastern  Washington  has  an  arid  climate  and  most  plants  require  additional  regular  watering,  especially  while  becoming  established.    Last,  but  certainly  not  least,  are  the  pests  that  prefer  ones’  garden  and  orchard  to  their  natural  diet  and  would  ravage  these  if  homeowners  did  not  use  special  precautions  against  them.  

Kittitas   County,   not   unlike   many   counties   in  Washington,   has   differences   within   the   county  with   respect   to   rainfal l ,   e levat ion,   and  temperature.     Therefore,   the   length   of   growing  season   is   different   depending   on   location.    While  the  ground  may  be  workable  in  Ellensburg  (lower  county)   at   the   beginning   of   April,   it   may   still   be  covered  in  a  foot  of  snow  in  Roslyn  (upper  county).    

While   the   lower   county   may   require   minimum  winter   protection   for   most   crops,   upper   county  requires  maximum  protection  for  most  perennials  that  do  not  naturally  grow  there.  

At   higher   elevations   such   as   Ronald   (2,349   feet),  the   average   growing   season   is   90   days   with   last  frosts   in   early   June   (approximately   June   9th)   and  Iirst   frosts   in   early   September   (approximately  September   2nd);   In     Cle   Elum   (1,930   feet),   the  average  growing  season  is  90  to  120  days  with  last  frosts   in   late   May   (approximately   May   24th)   and  Iirst   frosts   in   the   middle   of   September  (approximately   September   11th).     Cle   Elum  receives   about   22”   of   rain   on   average.     At   lower  elevations   such   as   Ellensburg   (1,542   feet),  conditions   are  much  drier   and   frost-­‐free  days   are  longer.  The   average   growing   season   in  Ellensburg  is   about   120   days   with   last   frosts   in   early   May  (approximately  May   11th)   and   Iirst   frosts   around  the   end   of   September   (approximately   September  25th).    

Ronald,  Rosyln,  and  Cle  Elum  are  rated  USDA  Zone  4  (-­‐30ºF  minimum  temperature)  while  Ellensburg  is  rated  at  USDA  Zone  5  (-­‐20°F.  minimum).    

The   authors   of   this   e-­‐book   are   using   techniques  deemed   necessary   for   their   particular   region  within  Kittitas  County.  The   reader’s   to  do   list  will  be   speciIic   to   their   area   and   their   particular  climate.     Be   sure   to   check   resources   provided   to  determine  speciIic  climate  area.  

This  calendar   is  a  compilation  of  many  sources  of  information.     Many   thanks   for   the   outstanding  guidance  provided  by:  Washington  State  University  Extension,   Purdue   University   Cooperative  Extension  Service,  The  Morton  Arboretum,  Oregon  State   University   Extension   and   many   others   as  evidenced  by  the  extensive  use  of  hyperlinks.  

By    Laura  Stanley    and  Barbara  Raabe  Kittitas  County  Master  Gardener  

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Phone  (509)  962-­‐7507  

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