Oregano can theoretically survive winter outdoors in almost every climate and is hardy right down to -30°F (for reference, that covers most of Alaska!). So why is it so hard to grow outdoors here, and what can gardeners do to help oregano survive winter?
Well, the answer lies more in the type of winter than the temperatures you face. Cold, wet winters are much worse for these Mediterranean herbs than cold dry winters. So, snow, ice, hail, and rain should be avoided, but we’ve also got some valuable tips for oregano winter care to get these delicious kitchen herbs right through to spring.
Oregano is a hardy Mediterranean herb with woody perennial stems which come back every year. It is part of the mint family (Lamiaceae) and thrives in any climate with good sun and decent drainage.
Unlike most herbs, oregano actually has its best flavor when dried and is easy to harvest in summer for your winter larder. When fresh, its leaves can have a bitter aftertaste. When dried, oregano has a sweet earthy flavor that brings out the sugars in other food and adds a cozy flavor to most dishes.
What temperature can oregano survive?
One of the most common problems with oregano is that it rots in winter. It’s a common misconception that frost and freezing temperatures kill oregano in winter, when in fact, it’s moisture that usually sees an end to these delicious plants (illustrated by our table below).
Oregano hardiness table:
|Coldest winter temperature
|Is oregano hardy?
Why does oregano die off in winter?
Oregano dies in winter due to prolonged damp temperatures, and a lack of evaporation or need for water in the soil. When water is left standing, particularly in containers, it stagnates and harbors bacterial and fungal pathogens which attack the roots of plants.
Oregano is completely dormant during winter outdoors, following an active year of vegetative growth, flowering, and setting seed. So if your oregano browns off and drops its leaves, it’s part of a natural cycle and not a problem.
The problem starts when those plants are left in damp ground or pots are left sitting out in the rain through all and winter.
How to overwinter oregano
To help get your oregano plants safely through winter, bring them indoors, or move them to a sheltered spot. Obviously, this is easier for container-grown plants, but it’s well worth digging up a clump of oregano from the garden and overwintering in a cold frame or greenhouse too. That way, even if your main plant dies, you’ve got a replacement ready for spring.
To prepare oregano in pots for winter:
- Cut stems back by about 2/3
- Move pots into a greenhouse, cold frame, or indoors.
- If that’s not possible, cover pots with fleece to keep most of the rain off.
To prepare outdoor oregano for winter:
- Plant it correctly. Add plenty of grit to oregano planting holes so that they are never sat directly in wet soil. Add a 2” layer of grit to the base of the planting hole to add extra drainage.
- For existing plants: Dig up half the plant, carefully teasing the roots away from the main plant.
- Prune back stems back by about 2/3.
- Store the division in a plastic pot away from rain, snow, or hail.
Pruning oregano for winter
Don’t over-prune oregano, as this can make it very hard for the plant to recover in spring after cold winters. In fall, when the flowers have finished and the leaves begin to drop, cut back around two-thirds of the top growth, leaving some foliage at the base of each stem. Not only will this prevent frost damage to top growth, but it will create bushier plants in spring.
Tip: Like mint, you can cut half of any oregano plant back to its lowest leaves in summer when it begins flowering. You can continue to harvest the flowering stems and will get a second flush of fresh leaves in late summer.
How to keep Oregano going through winter
To continue harvesting oregano right through winter, grow it in pots and prune back after flowering. Then bring it indoors to a warm, bright spot, where it will continue to grow new leaves through winter. Harvest sparingly and leave it for a few weeks in cooler temperatures for at least 3 weeks of dormancy before spring.
Oregano is one of my favorite herbs, but it took a long time to get right. We’re in zone 9 here, but the winters in recent years have actually had temperatures down to 0°F (zone 7). By pruning our oregano plants back to the lower leaves, and keeping them dry through winter, they burst into life in spring.
So, don’t always assume that warm climate herbs need warm winters, consider the other aspects of climate differences, like humidity, moisture, and wind. So, to answer the original question… yes, oregano will definitely survive winter.