What can I tell you – it’s been darn cold. Here in Duvall, WA we had snow followed by sub-freezing temperatures for several weeks. Today is the first day in what seems like forever when my grass has been green rather than frosty white so I ventured out into the garden to see how things had held up. It wasn’t pretty.
Following the weather forecast across the country these past few weeks I’m know I’m not alone surveying the aftermath of crazy winter storms, assessing one sad looking plant after another. This is where inexperienced gardeners would be tempted to grab their pruners – DON’T! Except in the case of dormant deciduous trees and shrubs, pruning can stimulate new growth which will get killed by the next frost and possibly cause die back further down the branch.
Before you start hacking, chopping or pruning take a few moments to read this post and determine if the plant in question is ….
Dead, sulking or sleeping?
The answer depends on the type of plant and the severity of the damage. Here are examples from my own winter-weary garden this afternoon
For the most part these are remarkably resilient and some of the most cold-hardy foliage in the garden. However if your Hinoki cypress looks like this, forget the pruners – get the spade out!
This has been on a slow decline for two years following a summer drought the year it was planted. I gave it a fair chance but when this much of the foliage is brown, it is toast.
If you have Blue Star junipers (Juniperus squamata ‘Blue Star’) with one or two small sections that have turned brown (a common occurrence in my garden during winter ) you will be able to snip that off in spring after danger of a freeze has passed, and by summer you’ll never know it happened.
Most of my conifers thankfully looked OK.
It is common to see brown or black, frost-damaged leaves on shrubs such as this winter daphne. The more exposed foliage suffers the worst; branches closer to the house or protected by adjacent shrubs or upper branches may be completely unscathed.
Although these brown leaves will drop, the plant itself is still fine with most buds and a lot of the inner foliage still intact. No action is needed other than raking up leaves as they fall. New foliage will grow in spring.
So much depends on location. This Goshiki Japanese holly (Ilex heterophyllus ‘Goshiki’) suffers frost damage and die back every year, yet another bush that is closer to the house and under a deciduous tree is completely untouched.
This young Spider’s Web Japanese aralia (Fatsia japonica ‘Spider’s Web) may eventually lose the blackened leaves but I expect I shall see new growth from the base (at soil level) as well as the main plant in spring.
Many shrubs are listed as semi-evergreen which means the plant will keep its leaves in mild winters but may lose the majority when the weather is colder. For me this includes abelia, and fringe flower (Loropetalum). No action on my part is needed until spring at which point I will prune out any branches that show no sign of life by late April and trim healthy branches back to the uppermost bud (thereby removing frost damaged tips). Some shrubs will grow from the base as well as breaking from dormant buds along the stems – leaving the frost-damaged branches in place will protect these inner areas.
Tender shrubs and perennials
Lavender falls into this category for me – some varieties are more cold hardy than others. Russian sage, hardy fuchsias and gaura should also be treated in the same way.
You can see this lavender plant has a mix of healthy silver needles and cold-damaged brown ones. DO NOT PRUNE UNTIL ALL DANGER OF FROST HAS PASSED. Right now there are signs of healthy silver foliage right down the length of each branch. Those lower, healthy buds are the insurance policy in case any more of the exposed areas get frost damaged. Avoid any pruning until temperatures are warmer as it will encourage the shrub to push out delicate and vulnerable new growth.
Rosemary is another tender plant for me and some do better than others….if only I could find the tags!
My Jerusalem sage (Phlomis russeliana) is another frost casualty.
I actually prefer to cut this to the ground in spring anyway as it helps maintain a nice shape to these shrubby perennials. My approach with this plant is to cut it half way back just to get it off the grasses. I will leave approximately 2′ of frost damaged stems in place to protect the crown from further frost damage before cutting the whole thing down to ground level in March or April when it is warmer.
Donkey tail spurge (Euphorbia myrsinites) was added to my garden last year to repel the psky voles so I’m really hoping it survives the winter despite my less than favorable clay soil, getting trodden on by deer and being frozen for several weeks.
I can see new growth at the crown and the tips themselves look OK even if the stems appear to have lost some leaves.
Even super-hardy perennials such as fleabane (Erigeron sp.) can suffer frost damage as can be seen by all the blackened leaves.
I wait until spring to pull these out, knowing that new foliage will be healthy and green. In fact leaving the frost damaged foliage in place can shield the inner leaves.
Rock rose, also called sun rose (Helianthemum cvs) is either evergreen or semi-evergreen. Mine are showing blackened leaves in patches which will eventually fall away. However I’m confident that new growth will emerge from buds along the branches in spring. I’ll just gently rake the groundcover with my fingers to remove any slug-enticing mush (a new horticultural definition for you).
In the case of my semi-evergreen dalmation iris (Iris pallida ‘Aureo-variegata’), the frost damaged leaves are lost – but new growth is already apparent.You can tidy it up by removing the old leaves now.
Finally, check your plants for frost heave. This deer and rabbit nibbled heucherella has been pushed up out of the soil with the freeze-thaw action. I need to dig a new hole and re-plant it correctly. Many smaller plants are susceptible to this.
Celebrate the Survivors!
Thankfully there are still many great looking shrubs and trees even in January. Besides the many conifers, Little Heath andromeda (Pieris japonica ‘Little Heath’) has to be a favorite of mine, especially with its rosy winter blush.
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