Northern zones are notoriously difficult locations for growing sweet cherries. Experts disagree on where the northern climate limits for the cherry is (Cornell has stated in the past that if your temperatures fall below -25 Fahrenheit, sweet cherries may not be for you). Most nurseries don’t offer sweet cherries even that cold-tolerant, and there’s a general consensus that sweet cherries are very hard to keep alive any further north than zone 5.
However… gardeners have been ignoring the rules for decades. If you can find a cold-hardy tree or fool a cold-sensitive tree into thinking it is in a warm zone – through strategic use of microclimates, tree protection, and other means – you may be able to build your orchard as an exception to the sweet cherry “rule.”
Choose A Cold-Hardy Cherry Tree
Not all cherry trees are the same, and the most important thing you can do to ensure survival of your mini-orchard is to start by selecting the right cultivar.
When you are shopping around for a cold-hardy sweet cherry tree, do you understand the difference between bush cherries, pie cherries, and sweet cherries?
Of these three cherry “types,” by far the most difficult to grow in a cold climate is the sweet cherry. The only tree I have consistently seen advertised as a cold-hardy sweet cherry tree is the Kristen Sweet Cherry, which is guaranteed cold-hardy to zone 4 by several nurseries.
Another variety I’ve seen advertised in multiple places as a cold-hardy sweet cherry is the Chelan cherry tree – but reports differ on the tree’s cold-hardiness, so it may take a few years before the final “specs” on this relatively new variety are pinned down.
Provide Trunk Protection
A widely accepted best-practice when gardening sweet cherries in zone 4 and colder? Wrapping, painting, or otherwise protecting the trunk.
Oddly enough, your goal isn’t to insulate the trunk from the cold. Your goal is to protect the tree from the warmth of the sun!
When a cherry tree goes dormant for the winter, it is protecting itself. Systems shut down, and the tree essentially “sleeps” throughout the cold months like a hibernating bear.
If the tree wakes up too early, the cold weather can destroy its fragile tissues. That’s exactly what happens when the sunlight hits a cherry tree during the winter months. When afternoon sunlight rests on the trunk, it can warm the bark just enough to make the tree “think” that spring has arrived.
If the tree does wake up, the shock of frigid weather when the sun goes down can destroy sections of bark, underlying woody tissue, and – if the tree broke dormancy far enough – the entire tree. This is called sunscald, and it is a MAJOR problem for cold-sensitive trees.
To avoid this problem, you have to keep winter sunlight from waking up your tree. Personally, I use tree tubes – tall, plastic tubes that I pop loosely over the top of “whips” when I plant new trees. Wraps accomplish essentially the same purpose.
Alternatively, you can paint the tree white (the color is important! Black attracts and holds the sun’s energy, while white deflects it).
Regardless of what method you use, make sure to monitor your efforts each year. A tube won’t last forever, and needs replacing as the trunk diameter grows. The same is true for wraps, and paint will need to be reapplied as well!
Make trunk protection an annual part of your fall maintenance schedule, and your sweet cherries will have a better chance of survival.
(Looking for an ag-extension source on sunscald in sweet cherries? This publication on sweet cherries by Cornell University covers sunscald and tree protection on page 4.)
Be Aware of Gardening Microclimates
You have to be very careful about where you plant a cold-tender tree. Gardening microclimates can make a huge impact on your plants’ survivability – and they are more common than you might think!
Where could a microclimate come into play? You will most often see additional climate zone fluctuations when you live in an area with varying topography that funnels cold air to or away from your orchard.
Other factors that could catalyze a microclimate include large bodies of water, or even man-made structures as small as a sun-warmed wall or as large as the urban “heat-sink” factor stemming from storage of the sun’s energy in concrete.
It’s fairly easy to recognize a microclimate, but it takes significant effort to adapt your gardens accordingly. Don’t plant cold-tender sweet cherry trees where they will be facing an additional cold-burden. Analyze your property’s topography and structure, and find a planting site that won’t sabotage your tree.
With some extra planning and effort, it is possible to get a sweet cherry tree to survive outside of its comfort zone (pun intended)… but a microclimate can aggravate the challenges beyond what the tree can tolerate. Know what to avoid!
Winterize Your Fruit Trees
There are steps you can take every autumn to ensure your tree is prepped for the long winter. Winterizing your sweet cherry trees will
Don’t skimp when it comes to steps like mulching to ensure the roots are protected. Yes, heavy snow can affect root temperatures for your fruit trees, but you can’t be sure that winter snows will arrive before cold temperatures do.
My area commonly sees a few weeks of low temperatures without any snow on the ground, so I can’t rely on snow as a natural mulch.
Additionally, you should plan ahead for heavier browsing pressure from the local wildlife. If your area has exceptionally snowy or cold winters, the deer, rabbits, and other herbivores will look to your trees as an alternate food source.
Sweet cherries have a hard enough time surviving the temperatures even without animal damage, so don’t leave them vulnerable!
Protect your trees with fencing, tree tubes, wraps, or whatever you can use to block access. In a pinch, I’ve even used a 55-gallon oil drum dropped over the top of the tree like a giant tree “tube.”
Growing Sweet Cherries in Zone 4
At the end of the day, it’s always going to be a gamble trying to grow a cold-tender sweet cherry outside of its “target” climate zone.
You may find it difficult to get past year one; alternatively, you might be able to get the tree through a few mild winters, only to be hit with a devastating freeze-injury from an unseasonal cold-snap just when the tree is about to bear fruit!
However, with a little extra selection, planning, and maintenance, you may be one of those fruit gardeners that beats the odds. Best of luck!
Interested in growing other stone fruits in zones 4 and colder? Check out my articles on growing peach trees!