cold tolerance of Rubiaceae

[dogbane26]

I am thinking that some tropical species within the Rubiaceae are more cold hardy than what most literature reports.  

Some people will say Mitragyna speciosa is hardy to 40 degrees.  I think it is much hardier than that.

I left my plant which has secondary growth/wood outside when it was 28 here in North Central Florida and it was damaged but survived.  It may of been a 4 hour freeze.

It may of also been protected somewhat since it was close to a sliding glass door so the temperature may of been warmer from the heat inside.  

What I observed is the larger older leaves were all damaged by the cold  but none of the younger undeveloped leaves and also I am thinking the anthocyanins may provide some protection.  The stem remained undamaged.

I am growing the red veined thai kratom.  Some of the leaves not damaged lost the red coloration in the leaves.

I left my Noni outside and all but the leaves at the node where the main apical bud is located were damaged.

Luckily my Noni plant is still alive.  It is interesting how plants can allocate damage from freezes so it doesnt kill the whole plant.  I am sure if I left the Noni outside again the whole plant would be killed.

[AliceTepes]

I have always been too afraid to kill my plants to even think of leaving them out in the cold. so I applaud you for testing that. a have few succulents that grow outside year round(and get is below freezing for the winter here) and a neighbor of mine has Optunia cacti in his front yard that can handle even below 0* tempatures.

have you left any Psychotria outside?

[Stonehenge]

Psychotria are fairly cold hardy. Freezing will nip them but unless it stays in the low 20's they will not die back much and the roots will often come back even if the above ground parts die. My kratom  survived freezing last year and died back again this year but i hope it's ok. Same for my v africana. Same for some of my caapi.

The garden is for edibles and ornamental discussions. This would be better in the rain forest.

[cunningplatypus]

On a related note, I'm curious if anyone has had experience with plants surviving/thriving in temperatures where they "should" be unable to.

As an example, I was in Eugene, Oregon in October. I was surprised to find banana plants and fig trees growing lustily, albeit in only a couple of locations. A quick look at Google tells me that the winter low in Eugene is just about freezing (33 degrees F). I didn't think that either of the two plants could survive in those kinds of temperatures.

I also believe that Catha edulis in one of its native habitats (Ethiopian highlands) tolerates some fairly chilly temperatures, though the common wisdom seems to be that it's entirely a hot-weather plant.

[Stonehenge]

I've seen khat survive occasional freezes. It depends, the narrow leaf did fine but the broad leaf not so fine. They will lose leaves in a frost. Heavy freezing is no good for them.

[Amomynous]

My psychotria have handled the occasional light frost with no ill effect (but of course I move them inside before any hard frosts).

[dogbane26]

Ive tried other plants in Florida and they survived the summer but didn't do so well in the heat. The leaves wilted alot, turned brown alot even when it was well watered.    

Salvia dorsiana( Fruit Scented Sage) seems to produce larger leaves and more flushes of leaves from November-April in Florida.  

 I am guessing some  Salvia species like California native Salvias might rot and even die from  fungal diseases even if underwatered and planted in a well drained soil because of the high humidity in Florida?  

Id like to try Salvia apiana but I am not sure how it will do in the humidity even if I keep it out of the rain which is almost impossible on my balcony.

I leave my Salvia dorsiana outside almost yearround in a pot.  I think it can tolerate freezes into the 20's.  I guess humidity isn't a problem since it grows in cloud forests in Guatamala, but the high heat tends to be an issue in Florida.

[hedgenursery]

I have always been too hesitant to eliminate my plants to even think of creating them out in the cold. so I enhance you for analyzing that. a have few plants that create outside period round(and get is below cold for winter season weather here) and a next entrance next entrance neighbor of my own has Optunia exotic in his access that can handle even below 0* tempatures.