I thought it would be fun to buy a Dahlia imperialis (tree Dahlia) double white form and see how many plants I could get out of it.

See the link at the bottom if you are not familiar with the plant. The most important limitation to be aware of is that Dahlia imperialis is both frost tender, huge and blooms late in the year. Unless you live in an area with little frost or have a tall greenhouse you may never see it bloom.

Here the plant is, from Annie's Annuals:

I posted a photo earlier of a Dahlia imperialis double white from Annie's Annuals. That was the same variety but a different plant. I won't give the details of the fate of the first one yet--I consider that my "practice". I'll just say I got at least one plant out of it so far.

Anyway, here's the deal. If you want a plant propagated from the one shown in the picture I will send you one for postage as long as I have a supply. If I turn the above plant into 3 plants, I will send it to the first 3 people who respond. So everything that results from this propagation exercise will go to someone who responds below.

Here's the "contest". I will also be propagating a second Dahlia Imperialis, the single pink form. If you can guess the number of plants I'll end up with within a month (yes, this will drag one for a while) then I will send you a rooted cutting of the other form, pending success in rooting it.

Here's the other guy, that I will be propagating just by cuttings:

So, if you are interested in a plant (it might be division, a rooted cutting, who knows) post here how many plants you think I will get (and thus how many I will send out for postage--all will be sent out). If you are the first to guess correctly, hopefully you will end up with both the double white and single pink forms of Dahlia imperialis.

Guessing zero plants would still get you one as long as there ends being a sufficient supply.

I talked to a professional grower of Dahlias (also, tree Dahlias) last week, and that's what he told me to do. He says they rot when they are sitting in soggy soil. He also said they root best if left outdoors, unless there's a chance of a freeze - then, drag them inside.

I'm not sure whether people should be allowed to revise their votes. I don't feel strongly either way and am open to suggestions.

Perhaps I should mention that I'd like to get Dahlia campanulata, depending on what the price at the retail store is, and depending on the timing I could add a cutting (hopefully rooted) of that.

Something tells me that it might end up on their "mail order only list". In that case I will definitely not get it. If anyone knows, or hears that it is available, let me know.

It's not a Dahlia, but if when I get Rojasianthe superba at Annie's, if there's a way to quickly propagate it, I will do that and add it to the "prize". I suspect I would have to wait either until it is large and branched, or makes seed, though. I don't know what time of the year they sell the plant.

Anyway, here's what became of the first double white D. imperialis, after I chopped it up (so it's about a week and a half later):

Clearly the three that were divisions containing a tuber and some growth should make it (top row, in pots). One actually had very little in the way of tuber, because it broke off. All of those divisions lost a lot of leaves, and our now putting out strong new growth. They need to go outside.

I don't think the broken tuber has a dormant eye (though it could, it's a close call). Its root growth is amazing.

I think the three larger cuttings will make it. I suspect they will put out roots in couple days.

I root most things in perlite under 24 hour illumination. This looks like it will work here, and that's what I'm doing for the single pink D. imperialis cuttings.

Anwyay, I will get anywhere from 3-6 plants out of that.

I chose the second plant so as to have the maximum number of viable pieces. Chosen from dozens of plants at Annie's retail store...

By the way, I do have another Annie's plant (bought at a small nursery nearby): Cobea scandens. I'm going to put that up for trade, probably with a whole bunch of other stuff, mostly rooted, maybe on the Hoya or tropical forum. I will be looking for rare most likely indoor stuff. Just in case you need anything to climb a Dahlia. This is a plant in a 4 inch pot that needs to be transplanted immediately (photo elsewhere).

Photo taken of a plant at a really cool (and new to me) nursery in Albany, CA called Flowerland (between Richmond and Berkeley). I did not buy the Cobea there. I did get an Akebia for my sister.

Here are the pieces that came from the other plant--I think this is the picture I sent you. I'm hoping to hit double digits, actually. I also took 3 small cuttings from what is shown here.

The one in the upper right has neither roots nor obvious growth. The two in the lower right have no obvious bud/leaf growth

Would you mind posting a tutorial on the process you used to get these cuttings rooted? Thanks!

The divisions looks like they are about to put on strong growth. I see green in at least 9 pots at this point--I think I'll know soon how many I get. The small cuttings do not look good--one has rooted and another appears to have started to rot.

The somewhat larger cuttings of the single pink Dahlia look better, although there are no roots yet.

The cuttings I took earlier of the double white: the one that had a root lost it (possibly I broke it off?), another one has rooted. I get the suspicion that these guys would do better in a perlite/peat mix than straight perlite, and may transfer them when they root.

New plant: I picked up Rosjianthe superba at Annie's Annuals ($7.50 for 1 gallon size). There were only 4 others out for sale, so I suspect my timing was good. There appear to be a bunch of future cuttings growing on the stems...

The plant looks like it is cutting grown.

I'll try to have a rooted cutting available for whomever is closest guessing. This could possibly delay things--we'll see. If the plant gives me material for multiple cuttings perhaps I will have more available. If possible, I would offer rooted cuttings to those getting D. imperialis 'Double White'. I have no idea how easy it is to root.

By the way, if the article I linked below from Strybing Arboretum is correct, the plant can live outside for virtually nobody during the summer due to intolerance of heat. I'll look/ask around and find out if that is indeed true.

BTW congratulations on your great rooting successes. I also would be interested in the process you used to get these cuttings rooted.
Thanks.
Clare

To follow up on your earlier question about a tutorial. The D. imperialis cuttings that came with a piece of tuber were easy. Those were just the result of dividing the tubers carefully so that each growing shoot ended up with a small tuber or piece of tuber.

Of course younger plants (such as the D. imperialis) single pink form, did not have tubers. There cuttings were the only way to go. I did start some small unrooted tubers of D. imperialis double white from the pot I divided above; however those appear less successful. Slightly larger cuttings of the double white form (from the first Annie's plant) were more successful.

Here's a description of how I root Passiflora cuttings. This is essentially the same as I used for D. imperialis cuttings (those without tubers, which are probably more accurately called divisions)

http://forums.gardenweb.com/forums/load/passiflora/msg100542156419.htm l

And here is a small cutting of the single pink D. Imperialis, just starting to root:

The root is in the lower left, pointing towards about "7 o'clock"

I have not been using peanuts lately (and I actually don't have a supply).

The 10 plants themselves are outside, but likely not getting enough sun. It might be easier to trim some of them back before maling. I'll have to contact those who were interested in them and figure out how/when to ship.

The Single Pink cuttings have generally stayed alive, and often put out short roots. However these have not been persisent, for reasons that are not clear (fungus gnats are one possibility). The thicker bamboo-like cuttings so far are mixed. One has a lot of leafy growth, but no roots. The others are not clear yet.

I have yet to see other varieties of tree Dahlia here.

I have Rojasianthe, but haven't tried a cutting yet. The largest of the sideshoots has just gotten big enough so that I can attempt one.

I will have seeds in a few days, probably, of Roldana petasitis, which is a (former) Senecio that has some features of tree daisies and grows a 10 foot bush.

Rferguson--I will probably have extra, but I don't want to commit to anything immediately. Please contact me directly and/or I'll try to remember to contact you.

Janine--I'm going to start trying to root some soon, and there are already a few people who are interested. Unless I kill the plant I should have rooted cuttings and/or seeds at some point. So far it seems pretty vigorous and a lot will depend on how quickly it branches and whether cuttings root easily. You might want to contact me in a couple months. I'm not sure if it's past the blooming season for this year or not (one site says February-May and I have not noticed buds yet). The plant appears to be cutting derived. Since Annie's generally prefers to propagate by seed, possibly there's a reason for this? (maybe either seeds are difficult/slow/etc. or cuttings are easy).