Hi Ruth,
Which Asarina is it?
I overwintered A. wislizensis as a tuber and there was a couple of feet of new growth when I potted them up this spring. As soon as I got them outside they filled out and I don't think pruning will benefit them.
If it is A. scandens they respond well to pruning and you can use your clippings to start more plants if you are so inclined.
I have grown others from seed but never over wintered them so that is the extent of my experience.
Alana

I overwintered these 4.

Asarina erubescens 'Magic Dragon'
Asarina A. erubescens 'Bridal Bouquet'
Asarina wislizensis 'Red Dragon'
Asarina purpusii 'Victoria Falls'

The 2 erubescens are the the ones that got to 6' or 7'.
Bridal Bouquest is okay, just really tall. It had something to climb on.
Magic Dragon had nothing to climb on and seems to be a tangled mess.
I didn't plan to repot, as I left them in the pots they were in last summer.

Bridal Bouquet is my favorite, but I have never overwintered it-I start with seeds every time I grow it. If you decide to prune either of the erubescens, I would love it if you would follow up with how it responds.

Does Asarina in general make a large tuber or does it depend on the species?

Joseph

Joseph, this is my first time to grow asarina so I'm not sure.
I can see that the Asarina wislizensis 'Red Dragon' has small tubers because the squirrels keep digging in that pot.
I planted some of the Asarina A. erubescens 'Bridal Bouquet' outside in the fall and it's starting to come up now. I believe it is tubers also.

I have grown a few varieties of this species but yet have seen its root system. I guess I treated it as an annual.

I will have to grow a couple more to check out the underground scene this summer.

Joseph, the tubers for A. wislizensis look kind of like small fleshy versions of Dahlia tubers. I don't leave any soil at all on them and keep them in a place that gets very cool but does not freeze.
A. erubescens (now Lophospermum erubescens) forms a similar tuber but I have never provided them the cool dry storage they require to overwinter here.
A. scandens probably forms a tuber too, but I have never checked the pots for them.
I choose to save wislizensis tubers because they are the slowest to bloom from seed for me.

Thank you Ruth and Alana!