Growing plants in hardiness zones outside their usual range

[moriel]

Japanese black pines can do very well in my zone 9b. Either potted trees or in the ground, no issues provided that they receive adequate light, water, soil, and nutrients.

However, I don't see many people attempting anything with Japanese White or Red pines in my area. I have a beautiful young JWP that's doing pretty well in the ground. But if you go to the local nurseries this time of the year you'll see Monrovia's potted JWP 'glauca nana' almost dead. The nursery will have them on discount 50% by the end of summer, and of course nobody in their right mind would buy any of those trees. It's funny because I see this happening every year and they don't seem to be doing anything to prevent this, no shade cloth or location change.

I also have other plants that are not recommended for zone 9b, such as Japanese snowbell (styrax japonicus) and Japanese umbrella pine.

What's your experience growing bonsais outside their usual range?

 

[penumbra]

All plants are more adaptable when they are young. They most often lose this adaptability as they get older. That JWP that is doing well for you now is likely to begin its decline in the future.

 

[moriel]

That JWP that is doing well for you now is likely to begin its decline in the future.

Not necessarily if you have a microclimate. I'm fortunate that a small creek crosses my property; about one acre is covered by ancient oak trees that lower the temperature considerably in summer. Of course if I put my trees near the black asphalt in the driveway, the outcomes would be catastrophic. But near the pond old and young conifers are thriving.

 

[Shibui]

That JWP that is doing well for you now is likely to begin its decline in the future.

Not sure how old the white pine will have to be to start decline. I've had 3 here for around 20 years with no sign of problems. My Mugho is closer to 40 years and apart from some rot in the trunk it appears as healthy as ever, despite being well outside its natural climate range.
It appears that a great many people are willing to throw in their theories as fact without any, or very little, first hand experience.
My very first white pine only lasted a couple of years so I assumed that the naysayers were correct and even started telling others that white pine won't grow in this area. More recent experience with the trees mentioned above probably means the original tree died from something other than climate related issues and that JWP can actually exist here.
I'm all for pushing boundaries and not giving up at the first hurdle.

Not sure what other species I grow that are outside their normal range because I don't often check what I should or should not be able to grow.

 

[Kanorin]

I think what @penumbra is concerned about is a potential lack of winter dormancy hours. Many hobbyists from the not cold parts of California have struggled to keep alpine pines thriving long term. But then again, there are so many micro climates there that two people separated by 50 miles may experience success vs. failure.

Please keep us updated on how it does in the future and if you can look it up, how many hours below 42 degrees F you get each winter (on average).

 

[moriel]

potential lack of winter dormancy hours.

I'd be more concerned about deciduous trees and the lack of winter dormancy hours. I'm always looking for scientific studies on deciduous trees to know what's the minimum dormancy period for each species. Unfortunately, I've only found studies done on specific cultivars of Japanese maples and we know that different cultivars can respond quite differently. Maples natives to China and Japan, such as trident maples, are very popular throughout California.

 

[Kanorin]

I'd be more concerned about deciduous trees and the lack of winter dormancy hours. I'm always looking for scientific studies on deciduous trees to know what's the minimum dormancy period for each species. Unfortunately, I've only found studies done on specific cultivars of Japanese maples and we know that different cultivars can respond quite differently. Maples natives to China and Japan, such as trident maples, are very popular throughout California.

Michael Hagedorn’s book “Bonsai Heresy” references a few studies I believe.

 

[MaciekA]

I also have other plants that are not recommended for zone 9b, such as Japanese snowbell (styrax japonicus)

This is wildly super duper not true. Styrax is bat-shit amazing in zone 9. Strong runners to the ceiling of the workshop, defoliate/cut/wire multiple times a summer. What source claimed specifically this? Portland is mostly zone 9 and must have literally thousands of snowbells growing in the landscape, I see them every day on every run/walk. Grow styrax, it is awesome.

 

[Paradox]

@moriel
@Shibui

Are your JWP grafted or on their own roots?
What are your winters like?

 

[moriel]

This is wildly super duper not true. Styrax is bat-shit amazing in zone 9. Strong runners to the ceiling of the workshop, defoliate/cut/wire multiple times a summer. What source claimed specifically this? Portland is mostly zone 9 and must have literally thousands of snowbells growing in the landscape, I see them every day on every run/walk. Grow styrax, it is awesome.

https://www.monrovia.com/japanese-s...dpiQ4TOR_6YSXp9A7mhRlb4dIgFToQV1qrJe5DpfBsqWr Zone 5 to 8, not found in our local nurseries. I agree that styrax does well, provided that it gets enough water in summer.

Are your JWP grafted or on their own roots?

I'm not sure honestly. I've heard that almost all JWP found in nurseries are grafted, but I can't see any graft line on my tree. I tried asking the people at my local nursery (where I purchased it), but they didn't know either. I guess I could try contacting the supplier directly.

 

[leatherback]

I'm not sure honestly. I've heard that almost all JWP found in nurseries are grafted, but I can't see any graft line on my tree. I tried asking the people at my local nursery (where I purchased it), but they didn't know either. I guess I could try contacting the supplier directly.

Show clear pictures of the trunk from multiple sides..

 

[Shibui]

Are your JWP grafted or on their own roots?
What are your winters like?

I have JWP from seed and cuttings (own roots) and grafted onto JBP. All seem to be growing well but I have nothing to compare growth rates and health with but they are all alive and growing for more than 15 years now.
Winter nights here dip just below freezing for a month or so. Extreme cold night is -4C. Snow falls once maybe every 15-20 years. Winter days are sunny and always above freezing.
This winter was warmer and shorter than usual though we did have a couple of extra cold nights around -4C during one cold snap.

 

[MaciekA]

https://www.monrovia.com/japanese-s...dpiQ4TOR_6YSXp9A7mhRlb4dIgFToQV1qrJe5DpfBsqWr Zone 5 to 8, not found in our local nurseries. I agree that styrax does well, provided that it gets enough water in summer.

Maybe worth mentioning my styrax came from a grower in the central valley in CA, just one out of a big batch of trunks grown over years. Monrovia shouldn’t be using the frost hardiness zone to classify this because the ground surface area of zone 9 and 10 places that can grow it in the US alone is probably the size of a state or small country

 

[Maiden69]

My Mugho is closer to 40 years and apart from some rot in the trunk it appears as healthy as ever,

I tried a mugo and the sucker looked fine the first year then dropped dead. I checked the root ball and it looked fine, no pests or bad roots. It was a 3 year old in a 1 gallon container so I thought I was going to be able to adapt it. After that I have not tried to do any other conifer out of their zone.

JBP thrive in hot weather, so no surprise it is doing well in a zone 9, JRP does well too as far as I can tell. I have several JMs that have endured Texas heat for 3-4 years, as long as you protect them from the sun the entire summer. I don't think I have a long dormancy, most of them start loosing leaves around the end of November till January, and start budding out around the end of February, so far that seems to do the trick.

 

[Paradox]

I have JWP from seed and cuttings (own roots) and grafted onto JBP. All seem to be growing well but I have nothing to compare growth rates and health with but they are all alive and growing for more than 15 years now.
Winter nights here dip just below freezing for a month or so. Extreme cold night is -4C. Snow falls once maybe every 15-20 years. Winter days are sunny and always above freezing.
This winter was warmer and shorter than usual though we did have a couple of extra cold nights around -4C during one cold snap.

Honestly I don't think your climate is all that bad for JWP. I've been told they like cold winters, but people keep them here in areas that have warmer winters than I experience.

If your night temperatures are typically below freezing for a month with days below 40F (4.4C) most of the winter, you're probably fine.

I am also a bit concerned with the trend towards warmer and shorter winters with trees that need dormancy. Time will tell if it truely becomes the norm

 

[eugenev2]

Fascinating topic this, because i still have to find advice that @Shibui provides that doesn't work for me, but interesting that our winters seems so different, ours rarely hit the minus degrees if ever, generally we have 0C to 5C for the lows with the highs of 15 to 22C, but we are both 9b...or i should say supposedly 9b...i don't know how accurate these usda zones outside of the us actually are. But it's interesting to read that my temperatures are just just enough for Japanese maple dormancy...possibly not for Japanese white pine tho, although there are some who grow them here.
Bougainvillea for example is not "supposed" to grow in most of the our areas, but you seem them everywhere so

 

[RaginCajun]

I am in zone 8b, keeping Scot’s pines and Japanese white pines going on 3yrs now with no issues.. they definitely need protection from the sun in northern Louisiana unlike the black pines but they are growing and doing well.
I’ve tried Japanese larch twice and sure enough, just as everyone says, once the temperature got in the 90s they started cooking. There was no helping it with shade, our shade temperatures reach 103 degrees plus in July and August every yr. It was worth the 2 seedlings I tried just to watch them open up in the spring. I think Japanese larch are beautiful trees. Wish they would work here.

 

[Shibui]

I tried a mugo and the sucker looked fine the first year then dropped dead. I checked the root ball and it looked fine, no pests or bad roots. It was a 3 year old in a 1 gallon container so I thought I was going to be able to adapt it. After that I have not tried to do any other conifer out of their zone.

The first JWP I had died after a year so I assumed that was because it was outside its normal climate zone - lots of advice telling me this was the reason - so did not try again for many years.
When I finally did try again I was surprised to find they grew well.
I guess the moral of this is that what we assume is the cause of something may not be so.

 

[RaginCajun]

The first JWP I had died after a year so I assumed that was because it was outside its normal climate zone - lots of advice telling me this was the reason - so did not try again for many years.
When I finally did try again I was surprised to find they grew well.
I guess the moral of this is that what we assume is the cause of something may not be so.

The first one I tried died as well.. I thought it was because it was outside its “zone”… when I took it out of the pot and inspected the roots I found the roots girdled so bad it made me believe right away that was the cause of its death.. I tried again and haven’t had any issues.

 

[gooeytek]

I've seen banana trees, tropical hibiscus, and others that shouldn't be outside during our winters here in NY/7a, and yet they've been surviving.

The banana trees are normally cut down to about 8" above the soil surface, then covered with the cut banana leaves, left to endure snow and freezing temps.
It starts growing again the following spring.

We have a tropical hibiscus that was kept indoors, and had an aphid/gnat infestation that was pervasive despite applying a systemic insecticide last year. I've left it outside since last fall, expecting it to just wither and die. It's grown back lusher than ever. I hope I didn't just jinx myself