diff --git a/biogeochem/EDPhysiologyMod.F90 b/biogeochem/EDPhysiologyMod.F90
index 4c6bbb8a4e..cc6e498094 100644
--- a/biogeochem/EDPhysiologyMod.F90
+++ b/biogeochem/EDPhysiologyMod.F90
@@ -661,10 +661,31 @@ subroutine phenology( currentSite, bc_in )
     endif
     !
     ! accumulate the GDD using daily mean temperatures
-    if (bc_in%t_veg24_si .gt. tfrz) then
+    ! Don't accumulate GDD during the growing season (that wouldn't make sense)
+    if (bc_in%t_veg24_si .gt. tfrz.and. currentSite%cstatus == phen_cstat_iscold) then
        currentSite%grow_deg_days = currentSite%grow_deg_days + bc_in%t_veg24_si - tfrz
     endif
     
+    !this logic is to prevent GDD accumulating after the leaves have fallen and before the 
+    ! beginnning of the accumulation period, to prevend erroneous autumn leaf flushing. 
+    if(model_day_int>365)then !only do this after the first year to prevent odd behaviour
+
+    if(currentSite%lat .gt. 0.0_r8)then !Northern Hemisphere                                           
+      ! In the north, don't accumulate when we are past the leaf fall date.
+      ! Accumulation starts on day 1 of year in NH.  
+      ! The 180 is to prevent going into an 'always off' state after initialization
+      if( model_day_int .gt. currentSite%cleafoffdate.and.hlm_day_of_year.gt.180)then !
+       currentSite%grow_deg_days = 0._r8
+      endif
+     else !Southern Hemisphere 
+      ! In the South, don't accumulate after the leaf off date, and before the start of
+      ! the accumulation phase (day 181).  
+      if(model_day_int .gt. currentSite%cleafoffdate.and.hlm_day_of_year.lt.gddstart) then! 
+        currentSite%grow_deg_days = 0._r8
+      endif
+    endif
+    endif !year1 
+
     ! Calculate the number of days since the leaves last came on 
     ! and off. If this is the beginning of the simulation, that day might
     ! not had occured yet, so set it to last year to get things rolling
@@ -694,9 +715,12 @@ subroutine phenology( currentSite, bc_in )
     if ( (currentSite%cstatus == phen_cstat_iscold .or. &
           currentSite%cstatus == phen_cstat_nevercold) .and. &
          (currentSite%grow_deg_days > gdd_threshold) .and. &
+         (dayssincecleafoff > ED_val_phen_mindayson) .and. &
          (currentSite%nchilldays >= 1)) then
        currentSite%cstatus = phen_cstat_notcold  ! Set to not-cold status (leaves can come on)
        currentSite%cleafondate = model_day_int  
+       dayssincecleafon = 0 
+       currentSite%grow_deg_days = 0._r8 ! zero GDD for the rest of the year until counting season begins. 
        if ( debug ) write(fates_log(),*) 'leaves on'
     endif !GDD
 
@@ -907,7 +931,7 @@ subroutine phenology_leafonoff(currentSite)
     real(r8) :: store_c_transfer_frac  ! Fraction of storage carbon used to flush leaves
     integer  :: ipft
     real(r8), parameter :: leaf_drop_fraction = 1.0_r8
-
+    real(r8), parameter :: carbon_store_buffer = 0.10_r8
     !------------------------------------------------------------------------
 
     currentPatch => CurrentSite%oldest_patch   
@@ -936,8 +960,11 @@ subroutine phenology_leafonoff(currentSite)
                                                                 ! stop flow of carbon out of bstore. 
                    
                    if(store_c>nearzero) then
-                      store_c_transfer_frac = &
-                            min(EDPftvarcon_inst%phenflush_fraction(ipft)*currentCohort%laimemory, store_c)/store_c
+                   ! flush either the amount required from the laimemory, or -most- of the storage pool
+                   ! RF: added a criterium to stop the entire store pool emptying and triggering termination mortality
+                   ! n.b. this might not be necessary if we adopted a more gradual approach to leaf flushing... 
+                       store_c_transfer_frac =  min((EDPftvarcon_inst%phenflush_fraction(ipft)* &
+                            currentCohort%laimemory)/store_c,(1.0_r8-carbon_store_buffer))
                    else
                       store_c_transfer_frac = 0.0_r8
                    end if
diff --git a/parameter_files/fates_params_default.cdl b/parameter_files/fates_params_default.cdl
index 41a49c5e42..82142bf816 100644
--- a/parameter_files/fates_params_default.cdl
+++ b/parameter_files/fates_params_default.cdl
@@ -1172,7 +1172,7 @@ data:
 
  fates_phen_drought_threshold = 0.15 ;
 
- fates_phen_mindayson = 30 ;
+ fates_phen_mindayson = 90 ;
 
  fates_phen_ncolddayslim = 5 ;