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| Winterkill on Roses, The How and the Why by Peggy-Anne Pineau |
"Gosh, that plant was supposed to be hardy!" If a person was a little bird in Maritimers gardens this time of year
you'd hear that a lot. Seasoned gardeners have become accustomed to some sort of winter damage on plants while
what most of us simply call winterkill.
What exactly is winterkill? Why does this happen? Should it happen to so called "hardy plants" and what, if anything,
can we do about it.
The most common form of winterkill is black, dead tips & branches of plants in spring that were green and healthy
the fall before. It can be less noticeable in the fact that shrubs like forsythia that fail to bloom or fruit trees that fail to
flower & bear fruit The bark of shrubs if one looks closely is cracked maybe just a little or as much as a gaping hole.
It can also be as drastic as a totally dead plant!
Why and to what extent this happens depends on many factors. First and foremost it has to do with the plants
genetic make-up. If it has inherited dominant genes that give it super cooled cells then it has a fighting chance to
survive winter; given that the fall temperatures continue to decrease gradually to the freezing point & stay there until
spring. The most common reason why hardy plants suffer winterfill is that temperatures remain very warm in fall and
then suddenly drop to freezing. A very common occurrence in Nova Scotia! This coupled with a very wet fall can
really do damage to plants.
Super cooled cells need time to shed water from within themselves and this can only be done if temperatures
steadily continue to drop. Heavy rainfall right up until freezing also limits the plants ability to shed water. When this
happens the water in the cells freezes and expands bursting the cell walls and killing the tissue. The result in most
cases is death or, if your lucky, bark splitting (frost cracking).
Bark splitting in many cases goes unnoticed by gardeners. It can happen from over fertilization in fall, after a hot dry
autumn followed by a very wet fall or by sharp temperature changes in spring. Winter sun scald can also lead to
bark splitting. Plants most susceptible are the ones that are newly planted or young stock (both have very thin bark).
Bark splitting can be found anywhere on the shrub; trunk, branches or canes. This doesn't always lead to the death
of the plant, that depends on the severity. It does give an entry point for diseases and insects that will weaken the
plant.
Desiccation is another kind of winterkill that damages our plants in winter. This happens when the ground is frozen
and the roots cannot supply the plant with enough water to compensate for its loss in the above ground tissues.
Evergreens, who's leaves are their needles really suffer form this. Climbing rose canes, even the hardy ones also
can suffer badly if planted in exposed places. Rhododendron leaves will curl , boxwood and yews will turn yellow to
brown.
Have you ever visited your garden beds in the spring thaw and found your perennials setting on top of the ground,
roots and all? This is caused by the soil freezing and thawing and unless you push them back down immediately
their chances of surviving are very slim. I remain firm on the belief that the only way to ensure your perennials
survival is to cover them to some extent so that the sun cannot warm the soil during the winter months. The key is to
keep them frozen, not keep them from freezing! Especially on a southern exposure!
Fallen leaves are an excellent source of free bed covering. Mother Nature knows what to do! Too bad a lot of us
don't take the time to notice and copy her example! Evergreen boughs do the trick wonderfully. The Christmas tree
in our home is recycled twice. First to cover some beds & then to the chipper for compost.
As you read this hopefully you will come to a better understanding of why some of your plants are damaged or die
over winter. Remember, plants are a lot like us humans. They are living things directly effected by their environment.
And a harsh one in the Maritimes at that! My advise to try to cut your losses goes as follows:
Keep your plants as healthy as you can. A plant is only as hardy as it is healthy! Diseased & damaged plants are
weak and are most likely to die in a severe winter.
you'd hear that a lot. Seasoned gardeners have become accustomed to some sort of winter damage on plants while
what most of us simply call winterkill.
What exactly is winterkill? Why does this happen? Should it happen to so called "hardy plants" and what, if anything,
can we do about it.
The most common form of winterkill is black, dead tips & branches of plants in spring that were green and healthy
the fall before. It can be less noticeable in the fact that shrubs like forsythia that fail to bloom or fruit trees that fail to
flower & bear fruit The bark of shrubs if one looks closely is cracked maybe just a little or as much as a gaping hole.
It can also be as drastic as a totally dead plant!
Why and to what extent this happens depends on many factors. First and foremost it has to do with the plants
genetic make-up. If it has inherited dominant genes that give it super cooled cells then it has a fighting chance to
survive winter; given that the fall temperatures continue to decrease gradually to the freezing point & stay there until
spring. The most common reason why hardy plants suffer winterfill is that temperatures remain very warm in fall and
then suddenly drop to freezing. A very common occurrence in Nova Scotia! This coupled with a very wet fall can
really do damage to plants.
Super cooled cells need time to shed water from within themselves and this can only be done if temperatures
steadily continue to drop. Heavy rainfall right up until freezing also limits the plants ability to shed water. When this
happens the water in the cells freezes and expands bursting the cell walls and killing the tissue. The result in most
cases is death or, if your lucky, bark splitting (frost cracking).
Bark splitting in many cases goes unnoticed by gardeners. It can happen from over fertilization in fall, after a hot dry
autumn followed by a very wet fall or by sharp temperature changes in spring. Winter sun scald can also lead to
bark splitting. Plants most susceptible are the ones that are newly planted or young stock (both have very thin bark).
Bark splitting can be found anywhere on the shrub; trunk, branches or canes. This doesn't always lead to the death
of the plant, that depends on the severity. It does give an entry point for diseases and insects that will weaken the
plant.
Desiccation is another kind of winterkill that damages our plants in winter. This happens when the ground is frozen
and the roots cannot supply the plant with enough water to compensate for its loss in the above ground tissues.
Evergreens, who's leaves are their needles really suffer form this. Climbing rose canes, even the hardy ones also
can suffer badly if planted in exposed places. Rhododendron leaves will curl , boxwood and yews will turn yellow to
brown.
Have you ever visited your garden beds in the spring thaw and found your perennials setting on top of the ground,
roots and all? This is caused by the soil freezing and thawing and unless you push them back down immediately
their chances of surviving are very slim. I remain firm on the belief that the only way to ensure your perennials
survival is to cover them to some extent so that the sun cannot warm the soil during the winter months. The key is to
keep them frozen, not keep them from freezing! Especially on a southern exposure!
Fallen leaves are an excellent source of free bed covering. Mother Nature knows what to do! Too bad a lot of us
don't take the time to notice and copy her example! Evergreen boughs do the trick wonderfully. The Christmas tree
in our home is recycled twice. First to cover some beds & then to the chipper for compost.
As you read this hopefully you will come to a better understanding of why some of your plants are damaged or die
over winter. Remember, plants are a lot like us humans. They are living things directly effected by their environment.
And a harsh one in the Maritimes at that! My advise to try to cut your losses goes as follows:
Keep your plants as healthy as you can. A plant is only as hardy as it is healthy! Diseased & damaged plants are
weak and are most likely to die in a severe winter.
- • Good plants begin with good, rich organic soil.
• Water in times of drought.
• Never fertilize with a high first number fertilizer in fall. You don't want new tender growth going into
winter. Use compost for autumn & fall feeding.
• Pay strict attention to plants in a southern exposure. Unlike common thought, southern exposures don't
cool down gradually in fall, plants stay too warm & thus don't shed the water as needed. There's nothing you
can do except apply evergreen boughs over them by late September. This cools them down away from the
suns rays and by total freeze up time they're prepared as best they can be. Leaves work well here too but be
sure to put something down to deter the mice population from setting up house in your prize plants!