Seeking your valuable advice for overwintering a deciduous and cold sensitive Hawaiian mesquite

[Mikecheck123]

This is my 3-year old Hawaiian mesquite ("kiawe")(Prosopis pallida). Zone 10a in California was almost too cold for it and there was lots of dieback every winter.

Now I've done a thing and moved to zone 7a. (It's a souvenir grown from seeds collected on a Hawaiian beach, hence why I'm doing this masochistic thing of dealing with a tree not suited to my zone.)

If it was an evergreen tropical like a ficus, I would considering getting a grow light setup.

But it's deciduous. Does a grow light even make sense for a leafless tree?

I suppose option B is to stick it in a greenhouse/polytunnel of some kind and hope for lots of luck. As my entire bonsai career thus far has been in zone 10, I'm facing my first real winter and am scared!

 

[Forsoothe!]

Since you're not going to get normal growth due to shorter growing season, abandon trying to make it big and just grow it compact, as is. It will make a nice little bonsai and grow a little anyway. They are slender in nature anyway. Plan on reducing it greatly after it loses its leaves and just stick it on the best windowsill you have for the winter. It will try to leaf out in late Feb or Mar, weakly, and you'll be chasing leaflets, but it'll live and recover nicely each year to go outside when the conditions are right. You should mull over what kind of architecture you want and wire for that before trimming it down. The existing long branches could be arranged into the spreading Acacia arched flat top or a wind-blown pretty easily, but they make a nice ~compact form, too, if you chase down to 2, 3, or 4 leafs before #4 or 5 extend. You can decide by watching the twigs extend. As each new leaf extends, the previous internodes also continue to extend. You decide what maximum internode length you will accept is, and take off the tip at or before the internode between #1 & #2 is that length. When the tip is removed all internodes on that twig will stop extending. Bi-pinnately compound leaves means that one "leaf" is a cluster of 6 leaflets, each having 20 or so sub-leaflets (as I am using the word "leaf"). I wouldn't repot until it is spends a few weeks outdoors next summer.

 

[Perrywinkle]

This is my 3-year old Hawaiian mesquite ("kiawe")(Prosopis pallida). Zone 10a in California was almost too cold for it and there was lots of dieback every winter.

Now I've done a thing and moved to zone 7a. (It's a souvenir grown from seeds collected on a Hawaiian beach, hence why I'm doing this masochistic thing of dealing with a tree not suited to my zone.)

If it was an evergreen tropical like a ficus, I would considering getting a grow light setup.

But it's deciduous. Does a grow light even make sense for a leafless tree?

I suppose option B is to stick it in a greenhouse/polytunnel of some kind and hope for lots of luck. As my entire bonsai career thus far has been in zone 10, I'm facing my first real winter and am scared!


View attachment 394045

I have a water jasmine that becomes deciduous and loses its leaves every winter. I place it in a south facing window during winter and it does fine. I don’t think it needs the light, but the warmth does it some good I think. As long as it doesn’t dry out, I think it should be fine to overwinter in a windowsill.

 

[Mikecheck123]

I have a water jasmine that becomes deciduous and loses its leaves every winter. I place it in a south facing window during winter and it does fine. I don’t think it needs the light, but the warmth does it some good I think. As long as it doesn’t dry out, I think it should be fine to overwinter in a windowsill.

Cool, thanks!

 

[Pitoon]

You could keep it in a small seasonal greenhouse that you can find at any big box store and keep it on a heat mat to keep the roots warm during winter.

 

[Mikecheck123]

Updated pic. This plant does just fine indoors over the winter. It goes fully deciduous and sheds all its leaves. It starts growing again shortly after the winter solstice.

I've decided that the biggest breakthrough came in when to bring it back out. In 2022, I brought it back outside on April 15, where it just got absolutely battered by winds and sulked in the low temperatures.

This year I waited until June 1, and it's much happier. There's basically zero benefit to bringing any of my tropical plants outside here before June 1. They don't respond to the extra sunshine because they're getting battered by wind and pouting in the cold.

The dieback was extensive this season as shown, but the new growth has already far surpassed it. It remains to be seen how it does next winter now that I think I know what it likes.