Cold hardiness zones

When you decide to start growing Tea roses the first thing you need to check is the number of your (cold) hardiness zone. 90% of all Teas and Tea Noisettes but also China's grow from zone 8b to 10b. Tis means they can be grown in temperatures between -12° Celsius and +35° Celsius or between 10/20 degrees Fahrenheit to 90/95 degrees Fahrenheit. Some Teas can take zone 7b and very few tolerate 6b. Zone 11b means tropical regions with all year round tropical temperatures with lots of moisture and it's no surprise that many Teas don't like that mixture.

Luckily, breeders like Viru Viraraghavan from India already started in the sixties to create more heat, drought and rain resistant roses. By crossing the European Teas with the wild R. Gigantea he has produced a few dozen of very heat / drought /rain resistant varieties perfect for hot and tropical regions. His work became even more important due to climate damage. Most European roses already are struggling with the much higher temperatures in Europe and the long periods of drought or rain. 

Viru died in December 2023 but his work will be passed on.

But what does it mean when you are living in zone 8b? It means that in winter the minimum temperature normally doesn't drop below -12° Celsius but in rare conditions it can drop lower. Even that's no problem as zone 7b is still a good zone with minimum temperatures of -16° Celsius.

But there are other aspects influencing the resistance of your Teas in winter. Dry, cold winds can dry out the wood of your roses causing major damage or even death and wet winters combined with severe frost can also be bad. Roses generally don't like winters with short periods of cold temp followed by short periods of milder temp. If it thaws several times in winter your teas won't like it. Better is a rather steady weather pattern in winter.

In Flanders (Northern part of Belgium) we have very mild winters combined with rather wet conditions. The past 14 winters had very few days with frost at night and in 2022 we only had 3 nights with frost from October till half of May and it never went below -7° in our garden.

Our garden is enclosed by old brick walls measuring between 5 and 2 meters tall. These walls keep cold easterly winds from Russia out of the garden and this has positive effects on our Teas. In summer, those walls absorb the heat of the sun making it even hotter in the afternoon and at night they slowly release that heat again. Lastly, these walls also absorb lots of water from the soil so it's essential to plant my roses at quite some distance from the walls and even then they need constant extra water in spring and summer especially the first year.

In another post I'll tell you what you can do to protect your Teas during days with severe frost.