The Tropical Fruit Forum

Thanks, I think I will try and source a variety, but flying dragon may be the best I can do.

Hello, just joined!

I live on the west coast of British Columbia, Canada. Technically zone 9, but I'll get into that in a sec. I've been growing mostly from seed, as I enjoy it, but also have a meyer and a sudachi. Living where I do, cold tolerance is a concern, especially because there is a high likelihood I will be moving to a zone 7 location in a few years.

In past winters, all my trees and seedlings have come inside in the winter, but I've gradually started leaving them outside longer...and then this winter decided to test them entirely outside. Of course this winter we had the coldest temperatures I have ever experienced in this location. It went down to -12 Celsius (10F), possibly a bit colder. In preparation for this, I moved my trees into an unheated garage and shed. They still definitely all experienced at least -5 (23F), the shed probably went colder. The most extreme was a Eureka lemon seedling and a rooted cutting, which were left wrapped outside the first night of the cold snap where it wasn't supposed to go below -5 (which I know it can take from experience), yet I woke up to -9. Presumably it was colder overnight. The pots were frozen completely solid. Fortunately, despite losing every leaf on the original tree, and all but 2 leaves on the rooted cutting, along with most of their branches, 2.5 months later both are putting on new growth. I lost a few seedlings, which I expected. The worst was a well-established potted meyer lemon which now has severe bark splitting. I sort of expect it to slowly die at this point. Compared to my seedlings it has always struggled. Do not know why.

What I am wondering is:

1. How do daytime highs impact citrus hardiness? A lot of zones are rated higher around here than most people think, partly because this is Canada, and partly because we tend to spend more time near the low end of our zones in the winter. Specifically I am looking ahead to my likely future, and wondering if poncirus is viable outdoors where it will experience cold snaps where temperatures do not come above freezing for days at a time.

2. My seed grown trees have been very impressive with their vigor, and now ability to withstand cold. What I am concerned about is their natural roots. Should I be acquiring poncirus for rootstock and grafting? Or are they likely ok if healthy so far? Does rootstock have any impact on cold tolerance?

3. My first store bought tree was the meyer lemon previously mentioned, and at the time I understood them to be hardy. Yet this plant has constantly struggled. No net growth over four years, constantly losing leaves, and now the bark splitting. Are there any reasons why this tree would struggle more so than others I have that are supposed to be less hardy?

Thanks in advance for any information that may help me better understand how citrus handle cold. Most of my learning so far has been my own from experience. Very little information about growing in this location.

I've included a pre-disaster photo of my "Shrimp-Ring Lemon". It is the Eureka lemon seedling I spoke about above. I call it that because I saved a single seed from a lemon wedge in a shrimp ring while preparing a batch of grapefruit seeds. It was an afterthought "why not" at the time, but is now one of my favorites, and fastest growing citrus trees. And apparently it can survive a pretty severe freeze.