Hardiness zones & growing tropicals in sub-tropical climates

[geeheeb]

Hi all! An insurmountable storm of doubts have gnawed at me for a while. Not sure why I didn't take the 30 seconds it takes to make an account here before.

I'm living in a climate that fits a 9a to 9b hardiness zone. I've seen a few successful Brugmansias here. While being tropicals, they're rated 8 to 11.
Now, Lophphora sp. are seemingly rated 8b {-9.4 °C (15 °F) to -6.7 °C (20 °F) }. But I've had Lophophoras dying from frost in my 9a zone.

So would you please give some guidance on how to use the hardiness zone chart to plan for growing other tropicals.

Thanks a lot!

 

[cpp gardener]

Welcome to the party!

Generally you can push the zones about half a zone cooler, as long as you can accept a few losses along the way. Expect to do some covering with bedsheets or plastic on extra cold nights. Some plants, especially cacti and succulents, are more sensitive to being wet AND cold more than just cold. If you are at the bottom of a slope, you will be cooler than upslope a bit; cold air sinks. A west-facing or north-facing wall (so weird to advise a warm north-facing wall) will give a little more warmth from re-radiated heat. It’s a matter of finding those little nooks that stay juuuuuust a little warmer than right over there. The zones are pretty good until you get right to the edges where small changes in topography or sun/shade affect temperatures.

Happy Plant Parenting!

 

[geeheeb]

Wow! All of that is on one hand so obvious, and yet on the other none of those factors occurred to me! Thanks a lot for your reply. A lot to think, plan and test! _/\_ <3