Spirea (from the Greek speira, or “wreath”) is a beautiful flowering shrub. It is deer resistant and tolerates poor soil, drought, and heat. That still leaves the question of cold hardiness, though.
So, can spirea tolerate cold? Many spirea varieties tolerate intense cold, surviving in USDA Hardiness Zone 5 (down to -20 Fahrenheit or -29 Celsius). Some spirea varieties can survive in Zone 3 (down to -40 Fahrenheit or -40 Celsius). For cold-sensitive spirea varieties, a row cover helps to protect the plant from extreme cold.
Some types of spirea can handle severe cold better than others. You can see this in the USDA hardiness zones for a given variety.
In this article, we’ll take a closer look at spirea cold hardiness and what happens if they are exposed to frost or freezing temperatures. We’ll also talk about ways to keep spirea alive if you live in the coldest regions.
Let’s get started.
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Can Spirea Tolerate Cold? (Spirea Cold Hardiness)
Many spirea (spiraea) varieties can tolerate cold – perhaps more than you think! This plant can survive winter in places that face long months of frost and freezing cold temperatures.
Specifically, most spirea varieties can survive in USDA Hardiness Zones 4 through Zone 8. Zone 4 can see temperatures as cold as -30 Fahrenheit (-34 Celsius).
Some spirea species (such as Spiraea alba or Spiraea trilobata) can survive in Zone 3, where temperatures may sink as low as -40 degrees Fahrenheit (-40 degrees Celsius) in winter.
Other spirea species (such as Spiraea cantoniensis or Spiraea prunifolia) can only tolerate Zone 5, where temperatures reach a minimum of -20 degrees Fahrenheit (-29 degrees Celsius).
Note that Zone 3 is cooler than Zone 4, Zone 4 is cooler than Zone 5, and so on. (You can look at a map to find your hardiness zone – and learn more about USDA Hardiness Zones – here).
Clearly, spirea can tolerate severe cold in winter! Even so, preparation is the key for plants to survive winter in cold areas and grow well when spring arrives.
Can Spirea Tolerate Frost?
Spirea (spiraea) can tolerate frost. Frost is a temperature of around 32 degrees Fahrenheit (0 degrees Celsius). Many species of spirea can withstand temperatures well into negative territory (some as cold as -40 Fahrenheit or -40 Celsius).
There is no need to worry about spirea due to a frost or freezing temperatures. Still, if you live in a USDA Zone with severe cold (like Zone 1 or 2), you will need to do something to protect your spirea from cold.
What Is The Lowest Temperature Spirea Can Tolerate?
Most spirea species can withstand temperatures as cold as -20 degrees Fahrenheit (-29 degrees Celsius).
Some types of spirea can tolerate temperatures down to -40 degrees Fahrenheit (-40 degrees Celsius).
If you grow your spirea in a medium sized pot, you can bring it inside during winter to avoid the worst cold. Otherwise, you can use a row cover on the coldest nights to keep the plant a little warmer (a heavy row cover can provide 6 to 10 degrees of frost protection).
If you live in Zone 4, choose spirea species that are hardy to Zone 4 (-30 Fahrenheit).
If you live in Zone 3, choose spirea species that are hardy to Zone 3 (-40 Fahrenheit).
If you live in Zone 2, choose spirea species that are hardy to Zone 3 (-40 Fahrenheit) and use a heavy row cover to give them a chance to survive in winter.
If you live in Zone 1, you might not have any choice but to plant spirea in pots and bring them indoors during the worst cold.
What Do You Do With Spirea Bushes For The Winter?
You don’t need to do much with spirea bushes for the winter. They are deciduous, so they will drop leaves on their own.
You can prune spirea if you wish – but do it at the right time! Otherwise, you might prevent your plant from blooming.
Pruning spirea in late summer or fall will remove flower buds, eliminating the possibility of flowers in the following year. For best results, prune spirea right after it blooms.
A harsh winter may cause damage to spirea that prevents flowering, at least during the next year. Check your USDA zone and compare it to your spirea’s hardiness zones.
Many spirea species can tolerate drought. Once established, they are very low-maintenance and don’t need much care.
In extreme drought conditions, a mulch of wood chips helps to retain soil moisture. (You can learn more about spirea’s water needs here).
In USDA Hardiness Zones 5 and warmer, you can leave spirea out for the winter. It will survive, despite the cold.
In USDA Hardiness Zone 4, you will need to cover (or bring indoors) any spirea species that are only hardy to Zone 5.
In USDA Hardiness Zone 3, you will need to cover (or bring indoors) any spirea species that are only hardy to Zone 4.
In USDA Hardiness Zone 2, choose spirea that are hardy to Zone 3 (-40 Fahrenheit) and use a heavy row cover to protect them from cold. This gives them a chance to survive winter outdoors (you can also grow them in pots and bring them inside).
In USDA Hardiness Zone 1, you probably have no choice but to keep spirea in pots and bring them indoors during the coldest part of winter.
Conclusion
Now you know the cold severity that spirea can tolerate (a surprising amount!) and how to ensure your plant makes it through winter in cold areas.
I hope you found this article helpful. If so, please share it with someone who can use the information.
Remember that spirea prefers full sun (6 or more hours per day) and needs at least partial sun (2 to 6 hours per day).
If you can’t find an area with at least partial sun, it is probably best to skip spirea and find something more shade tolerant. (On that note, you can find 10 great flowering ground cover plants for shady areas in this article).
You can learn about the best soil type and conditions for spirea here.
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~Jonathon