Long story short, last year we bought five "Suniq XXL" hardy hibiscus to grow in containers. These are Dutch hybrids which produce a profusion of flowers and are, allegedly, better suited to containers than standard hardy hibiscus.

This year we discovered these to be grafted plants: never seen a grafted hardy hibiscus before, this was a first. How did I find out? Simple: out of five plants, only in one the graft had survived. In all the others only the rootstock had survived, giving rise to horrible spindly looking plants which were quickly eliminated. But the one plant which survived... here is how it looks now:





And this is the second flush of flowers after the first in June.

We'd really like to keep this plant going next year and move it to a bigger container but the problem is I have no clue of how to keep the graft from meeting the same end as its siblings. If somebody has any experience on the matter I'd be very grateful.

Hardy hibiscus died back every winter and completely re grow. There are none grafted, that woudn't work since they die back to the roots. Where do you live, are you in the US?

Hardy hibiscus normally does not need grafting but, since this variety may have been developed by a florist company, they may be grafting somehow to keep the size in check or grow plants faster in cold lcations.

If the problem really was due to the cold weather, the answer would be to bring the plant into a more protected location this coming winter. Review what your last winter's coldest temperatures and keep the remaining plant warmer. The problem is going to be how much warmer. Since you do not want to lose your investment and only have one left, I would do two things: propagate via cuttings (the resulting non-grafted plants may be somehow slightly different - taller, etc.) and treat this hybrid as a hibiscus rosa-sinensis (temperature wise). And remember to water the plant during winter as lack of water in dry winters might kill them... once a week or so, depending on local rains and local temps. Check the drainage holes every time you water to make sure that water drains freely.

Some reasons why a graft fails: when the root-stock and scion tissue is not lined up properly, due to adverse weather conditions, mechanical damage to the union, virus/bacteria, etc. For example, I had a graft failure on a fruit tree once because my mild winters had warm temperatures for a while. That made the tree break dormancy just as cold temperatures approached. In the Spring, there was only growth from below the graft union.

Hibiscus re grows every spring from different points at the root system- there is no central leader to attach a graft. I just can't see in my mind how a grafted hardy hibiscus can even be possible

Here is more info Frillylily. But I am with you. I have never seen them grafted for sale here in the US although I have seen some Canadian locations graft plants that are normally not grafted down here. And you may be able to produce a plant with multiple/different colors.

https://www.ehow.com/how_85268...

The photo in that article shows a tropical hibiscus, not sure if they just used that as a free stock photo they had available, or if that is what they are referring to grafting? I have never grown a tropical hibiscus since they are not hardy here (too cold) but maybe those do have a central 'trunk' that is grafted onto? But the original poster's photos do seem to be of hardy ones. The only ones I've seen around here that bloom different colors are the grafted rose of sharons or the luna series hibiscus that they plant multiple plants in one pot and each is a different color that grow up together-giving it the appearance of a bush with different colors.

I can assure you that's not a tropical hibiscus. I know them very well as my mother grew them by dozen in the days.
This is some sort of hardy hibiscus with a spreading habit: don't know if it's just a cultivar of H. moscheutos or if it's an interspecific hybrid, but that's hardy alright, including the speed at which it grows in June. The plant you are seeing died back last Fall, was cut to the grown and behaved like any old hardy hibiscus.

I m-a-y have pictures somewhere (I'll try to dig them out) but a post-mortem of the spindly plants revealed what looks a whole lot like a dead 2" tall graft just below ground surface through and around which developed shoots from the rootstock. The rootstock is clearly a H. mosceutos, but with very spindly habit and clearly not developed to bring flowers: don't know if it's a volunteer or, much more likely, a cultivar developed to be a rootstock but it's really ugly. Never seen anything like this: I have two H. moscheutos in the garden (one Planet Griotte and one Fireball) and while there's clearly a relationship these "Suniq XXL" are clearly very sophisticated stuff.

That small graft on top is what I am trying to keep alive, but the instructions that came with the plant just say to "prune in the Spring". Thanks a lot.

Here's a bit of info on this one. Not much but a bit.

https://www.havlis.cz/karta_en...

pepper23 said:Here's a bit of info on this one. Not much but a bit.

https://www.havlis.cz/karta_en...

"Overall plant height of 50-60cm". Perhaps while it's growing up.