Taking Dahlia Cuttings

blown_dry · 2023-02-04T23:34:14+00:00

Continuing from https://cubits.org/Dahlias/thread/view/92091/#end_of_thread

KitCMC

Teddahlia has anyone mentioned planting deep and burying leaf nodes - similar to tomatoes?

I often grow these cuttings (or expensive, new release tubers) in 7-10 gallon grow bags. It allows me to grow them later into the season. I pull them in and out of my garage at night/in morning all fall to give tubers extra time to develop. Would work even better in a greenhouse/high tunnel. Probably not an issue for warmer zones.

SteveM

KitCMC has anyone mentioned planting deep and burying leaf nodes - similar to tomatoes?

That is a great way to increase tubers. Bending a branch over and burying it will form nice tubers at every buried node. Can be a bit tricky to find when digging if the location is not marked.

SteveM

Teddahlia When you buy an expensive cutting. how do grow it to be sure you get some tubers?

A couple of ways to "force" tuber formation:

Grow the cuttings under short day lengths to promote tuber formation. I define anything less than 12 hours as "short day" but that is just a general guideline and could be off by a few hours (might be closer to 10 hours?). Also, it is actually the length of the dark period that is important and not the day length (even though I say 'day length').
grow the cuttings in small pots to stress the plant and induce tuber formation. Other types of stress might also work but I have never experimented with other stresses. Maybe nutritional stress would also work?

MIDahlias

At the last local society meeting we were told, that if you don't plant a node, you can still get a plant that will bloom but it will not give you tubers. Now, I'm questioning if when I just cut up the three small plants I had if I was greedy and didn't plant a node on each. Time will tell.

MissyWeitzel

I know there is much discussion and varied opinions regarding how many hours to have seedlings and cuttings under grow lights before planting out. There may very well be other drawbacks to my light to dark ratio, but I have always had my grow lights set for 12 hours on and 12 off. If the cuttings have been around and rooted for a bit before I plant them out, they always have small tubers already forming that I can feel as I pull them out of their trays to plant. The only time I have gotten roots only from cuttings were ones that other people made. I have always gotten at least a small tuber clump from every cutting, with leaf node cuttings producing the smallest clumps.

Is it my light ratio while the cuttings are rooting? Is it magic and happenstance? Not sure. Since I always get tubers, I'll just keep doing what I do.

I have experienced that burying more nodes, whether it be by planting more deeply or by covering a stalk definitely works and those tubers are perfect with easy to find eyes. Usually 3 tubers per node. Heck - tubers will form even if the stalks are merely laying on the ground and not buried. I discovered this when a windstorm nearly took out my pompon patch. I didn't have them planted tightly enough to hold each other up with the corral method and several stalks of several cultivars just lay on the ground from August 'til frost and all of them had nice tubers on the stalks!

Juliarugula

MissyWeitzel The only time I have gotten roots only from cuttings were ones that other people made.

I don’t know if this is the case for you or not, but for me, I’d take it a step further and say that the only times I have gotten roots only from cuttings were ones that were shipped to me from other people. I’ve always wondered if it’s the added stress of shipping that sometimes causes problems. I would say that it’s because cuttings shipped to me have had less time for tubers to form (since they might have been shipped late, etc), but! I’ve received mailed cuttings, planted them, and then rooted the first pinches, and gotten tubers from the pinches, but not the original shipped cuttings!

(Some shipped cuttings I’ve had no trouble with, however…)

SteveM

MissyWeitzel Is it my light ratio while the cuttings are rooting?

Yes, your 12 hour nights are right on the edge of not forming roots. If you gave even longer nights your cuttings will only callus over and not form roots at all. For me, cuttings that have only roots are more desirable than cuttings with tubers. In addition to starting faster when planted out, the first blooms are fully double instead of open-centered. The long day length treatment is especially important if you grow seedlings and plant the seedlings out early in the spring. At my latitude, I will not get fully double blooms if I plant outside when the day length is less than 12.5 hours (April 1)

Any (most) commercial grower that ships cuttings will root the cuttings under long-day lighting . Some growers leave the lights on 24/7 to ensure vegetative growth and fast rooting. I keep my lights on for 16 hours and don't like to go much shorter than that. The mother plants also need to be kept on a long day schedule.

Maybe I am straying from the original question...

KitCMC

MissyWeitzel do the 12 on, 12 off cuttings adjust to longer days without any issue when you transition them outside in the spring?

MissyWeitzel

SteveM interesting, thank you. Maybe I'll play around with 24 hour lights on one of my racks next season. 😊

SteveM

MissyWeitzel The 12/12 ratio you are using might be the secret to growing early pot tubers and something I will consider if I ever decide to sell pot tubers. Too many experiments, not enough time!

MissyWeitzel

KitCMC Yes! Usually I harden them off pretty slowly so it isn't such a shock. Shade for a couple hours for a day, then 1 hour of sun and a few hours of shade, then 2 hours of sun, etc. over a week to 10 days.
Last year I accidentally went too fast with sun exposure and I killed a bunch of them, but I won't make that mistake again! I will now set a timer on my phone so I remember to get them out of the sun at the appropriate times. When late April and early May weather cooperates, I actually have them all living outside in trays for several weeks before planting. They go in the garage at night if the temperature drops, but I always feel a lot better planting them out when they have been accustomed to the temperature fluctuations in addition to light differences for as long as possible!

KitCMC

MissyWeitzel Thanks Missy! Might try a little 12/12 test this spring.

KitCMC

I was looking over my cutting tray this evening and noticed that a potted tuber has some greenish mold on the crown area, around the sprouts. I separated it from the "herd" immediately. I've taken one cutting from this one, which luckily has already rooted. Pics of mold below.

I will make sure to reduce the general moisture/humidity, but is there anything I can do to prevent mold from spreading through this area like wildfire? This one, and all the others, are potted in Pro-Mix BX.
Does anyone have advice for how to help this particular tuber? Is it trash? I would love to get another cutting or to at least plant it. I think one/some of you have mentioned lysol . . .

MIDahlias

Since I'm only still experimenting with cuttings myself, I have a question about a cutting I received.
The cutting
Arrived in a clam shell
Securely packaged
The total length of the plant is 7.5"
2" was the rooted area wrapped in a wet paper towel
3 leaf sets were removed from the soil medium up 3"
The top 3" had 3 small leaf sets

The cutting is now dying and has severe powdery mildew.

I potted it up on day two. I've had it 4 days and I have to throw it away. Edit: I'm going to cut it down and see if it regrows.

I have successfully potted up 5 cuttings and taken getting ready to pot up a sixth I received from a society friend in a 2" pot last Tuesday. All six of these plants look great.

Is the plant dying because so many leaf sets were removed? Is it more likely to get powdery mildew because it's trying to recover from the leafs being removed?

SteveM

MIDahlias Is the plant dying because so many leaf sets were removed? Is it more likely to get powdery mildew because it's trying to recover from the leafs being removed?

I'm guessing the vendor removed the lower leaves before shipping because they were mildewed. I would notify the vendor and let them know of the mildew. A good vendor will want to know and will probably offer you a refund or replacement.

If you try to save it I would do as Ted recommends. And keep it away from your healthy plants.

Teddahlia

I just got off the phone with club member who has powdery mildew on a cutting plant he got from a friend. Comment: If it ain't fungus gnats it's powdery mildew. 😳
The least "chemical " solution is hydrogen peroxide. 3 to 1 as a spray on the leaves, once per week. More powerful chemicals are out there but if this works, hydrogen peroxide is very safe.
Tubers die generally because thy have rot and it is generally incurable., although surgery may save it. The powdery mildew you get from "friends" may be a version that is hard to control.

edewitt

Well I made the mistake of taking my time with digging up my tubers and should've just left them in the ground as the sprouts are quite big. They're already withering today and I'm not sure if that's gonna ruin the eye for good if it continues. Should I just slice off the sprouts for now and take what I can for cuttings to save the eyes on the tubers?

SteveM

edewitt In the past I have dug clumps with 6-8" sprouts and chopped the clump in half (with a shovel) and immediately replanted with 2-3 sprouts/clump. They looked pretty sad for a few days but eventually took off. I don't know how it would damage the eyes unless the sprout rotted back to the crown. I would probably water them in well and give them some shade, if possible. Your air is less humid than mine but I would give them a few more days to see if they recover.

blown_dry

edewitt I'm never sure what to do with those either. That said, I don't think you have to worry about damage to the eyes. My limited experience is that if you divide conventionally, the big sprouts are often a loss and you may as well cut them off, but the tuber will perform fine, ultimately. The only loss is some growing time and maybe not much of that.

Dahlia53

I'm sorry - it's late and i don't have time to look back through almost 500 posts in this thread. I have a dilemma. My friend dug her Taratahi Ruby (which I had given her many years back). It seems to be weak and dying out. She gave me one tuber which had winter rot and didn't make it through storage. She gave me another; this one has a long sprout about a foot long and it was a double tuber start, but one was completely rotten and the rot looks to be in the remaining tuber when I went to cut off the rotted tuber, so I want to try to use this long cutting which is beginning to color up; it's not white anymore - because I think the tuber won't make it. Her double tuber seems OK - I left her the good one but I suspect the whole plant got rot in all its tubers and hers might die too.

If it could be rooted, how would I cut it down? close to the tuber or leave some sprout, even with no leaves? It is so long and spindly and I don't even think it has made two sets of leaves yet but everything is up near the sprout end. Has anyone tried this to save one of their dahlia varieties - and would it even work? Day lengths are rapidly increasing; maybe 15 hrs now. I've wanted Taratahi Ruby back for many years and have never had luck obtaining one in the dahlia sales. I don't even know if I have any rooting hormone but i can get some in the morning. would I need to make a little 'mini' greenhouse to hold in moisture while it roots?
I am going to try to find an article on this. If I need to buy rooting hormone, what should i buy? I remember someone talking about mycorrhizal rooting hormone and that they like it better - if i can get anything like that on an island with few choices.

What medium should I use and how deep to bury the end, if there are no obvious leaf nodes?How would the roots form if I didn't have at least one leaf node buried?

I also have a few 1" or shorter sprouts that have broken off. It's late but I thought to try cuttings on those, just as an experiment. Would any of these have the chance of making any tubers? I'm sorry if this is elementary and redundant or in the wrong thread. Any references, even to a post in this thread by its number, would be appreciated. If i am wasting my time and energy for no return, just tell me to forget it since I still have over too many tubers to plant in an overgrown, weedy garden so things are taking way longer than anticipated.

SteveM

Dahlia53 In addition to what Ted said:

If you are taken cuttings inside it is probably pretty dry air so most growers will place the cutting inside a plastic bag (or similar) which is closed at the top. This is to keep the humidity high until rooted. I do my cuttings outsider and the humidity here is high enough that I don't need an enclosure to raise humidity. Also, if doing inside, keep the lights on for 16+ hours/day to encourage roots.
Keep the temperature at 70-75F. High temps + high humidity will rot the cuttings.

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