Propagating dahlias - what gives the best results?

I've decided to plant (even) more dahlias this year, specifically a dahlia hedge which I'm hoping will consist of some very tall varieties, including a gorgeous wine-red cactus type I saved from last year. I've split this one up into three separate tubers and got two cuttings off them which seem to be rooting.

I've also bought loads of other tubers, some of which I've already divided with a knife and potted up.

My question is this: will I get more or earlier flowers from a cutting or a tuber? Also, will I get more or earlier flowers from a single undivided tuber or from the same tuber cut into two and grown on?

 

If dividing Dahlias you must make sure that each dividion has a stem bud attached,. You can`t just cut off a tuber and expect it to sprout because it wont. Go the cuttings route.

 

Each division has a goodly chunk of old stem tissue attached so I'm not too worried. Hate it when those useless bits of tuber drop off, though.

I'm really asking about comparative performance, not how to do it.

 

I am not sure of the answer - not having done the experiments.

However, I spoke to some people from the British Dahlia Society at a big flower show. I asked them how they propagated their Dahlias. They explained that it could be done by division or by cuttings, but they all personally said they did it by cuttings - as Dai said.

As far as the number of flowers is concerned, I suspect that you get more by division as each part has one or more tubers (ie resevoir of food). I think the reason for cuttings is that you can get many more cuttings from the same sized original plant. So logic says that with so many cuttings you will have more plants, but they will be smaller in the first year.

As far as flowering is concerned. The same logic would suggest that the divisions with tubers attached should have a head start and might do better. However, remember that most (but not all) Dahlias are short day flowering, which means that they won't start to flower until the daylength is less than 14 hours which won't be until about August. So an early start might lead to a bigger plant, but may not lead to earlier flowering.

There was a thread here on Dahlias http://gardenerscorner.co.uk/forum/...on/9537-dahlias-10-things-you-didnt-know.html

 

I've not grown dahlias for quite a few years, other than the odd "bishop of landaff ", but I always found you needed to take cuttings early, around Feb to get good results.
In many cases you could still divide the tuber after taking cuttings, and if you dont want lots of the same variety I think division is the way to go.

Regarding flowering, as Peter says, most flower with the shorter days, so getting them to flower earlier is not going to happen.
But divisions will always be bigger plants with more stems than plants grown from cuttings.
That just my experience, but I have grown them from seed also and had some pretty sizeable plants by Autumn, so the type and strain also plays a part.

 

If you know how to do it, then you`ve obviously tried it, so why ask?

 

MY view is that if you take a slip-cutting with some tuber then it will form a stronger tuber for next year. I expect you will get a stronger plant, and more flowers.

If you take a cutting above / at the first node then the sprout will break from the bud and you will either get more cuttings, or something to plant out but it will create a weaker plant / smaller tuber in the first year.

Depends a bit if you are after volume, or quality I reckon

 

I'm asking how good the results are, not how to actually carry out taking a cutting. I've taken cuttings before but not often of dahlias, and thought there would be people here who would know if there were advantages to each method - and there are! Yay!

 

Good point about the day length - mine are always late getting going. I'm sure other people get theirs into flower faster than me, however, so I wondered if there was some magic secret I was missing.

My feeling is that if you plant something out with a bit of tuber under it it should be stronger than a fresh cutting with a new rootball - but sometimes gardening is counter-intuitive!

 

This could be relevant. The tubers I used to harvest the cuttings have now each produced a crop of new growth points - maybe if I'd not cut the first shoots away these wouldn't have been triggered into growth. I definitely want more but smaller blooms, so I'll steel myself to pinching the tips out.

Anyone know how high I should let them get before pinching?

Great set of dahlia points - especially about the feeding and watering, always a bit haphazard in my plot.