Taking Dahlia Cuttings

blown_dry · 2023-02-04T23:34:14+00:00

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

SteveM

I have had fair results with "white cuttings" when I include the growing tip but no luck at all the one time i tried the "two-node" method. I have heard that some commercial growers use the two-node method with white shoots to great success but it was not me. I use the two node method with green shoots and have good luck.

bloomhjelm

I had no luck with white cuttings last year. They all seemed to want to still live underground.

There was a discussion yesterday on applying C02 to cuttings, maybe not in rooting stage but in growth stage. It potentially assists photosynthesis. I believe cannabis growers do this. Has anyone heard of this for dahlias?

SteveM

bloomhjelm Has anyone heard of this for dahlias

Co2 generators are used quite often in greenhouse growing, especially in the winter when the houses are closed up and don't get much outside air. I'm sure it would help dahlias but the systems and monitors can be pretty pricey so it would have to be a good sized operation to justify the expense. Maybe they make small systems for smaller spaces?

ksc

You would need high powered grow lights for the plants to utilize the extra co2. I believe the cannabis growers use co2 when your lights PAR value exceeds about 1500 whereas the average home growers lights put out about 100-200 PAR. The sun gives off a PAR value of about 2000 at noon on a clear day.

SteveM

ksc In a greenhouse, extra CO2 is beneficial during the daylight hours in a closed greenhouse. I have never used it but I believe the light levels are monitored automatically and CO2 is generated depending on the light intensity.

jistjul

Hello! I have a problem...I am starting my cuttings in the house, so the temperature is already 70-75. I have them under grow lights and a humidity dome, but with the dome on, the temperature gets to 85! I have the vents open and the dome partly propped open, but the temperature is just too high. How can I lower the temperature but keep the humidity high? without the dome, humidity is only 25%.

drewtheflorist

jistjul Move a bit farther from the lights

SteveM

jistjul How can I lower the temperature but keep the humidity high

If your lights are on 24/7 try decreasing the time to 16 on and 8 hours off.
Is 85ºF the constant temp and is it the air temp or the media temp?

jistjul

drewtheflorist I can't, the lights are as high as they will go.

Teddahlia

Too hot under the dome:
Every situation seems to be a bit different. What kind of lights? LED produce less heat than florescent. I liked my florescent lights as they had some heat and the temp in the room was a bit cool. I switched to LED for much of the area and have not noticed any heat difference but I have not taken temp readings. I did notice that the cuttings rooted 10-15% faster under the LED lights. Is that because I had more light(lumens) ? Probably, as fluorescents seem to get dimmer with age and I used "el cheapo" bulbs. Is 85F too hot? Maybe not but I have no experience.

jistjul

They are LED lights. Full spectrum. Thanks!

jistjul

SteveM Thank you! Lights are on 14 hours (on a timer) The temperature inside the dome (ambient air temp - not medium) is consistently 82 while lights are on. Humidity is between 50 and 60%.

Teddahlia

"Full spectrum" is what they say "grow" lights are. We are not generally "growing" dahlias under the lights but are rooting them. Growing means a full growth cycle : vegetative growth, blooming and production of seeds. I do not need "Full spectrum" bulbs to root my dahlias. I move them out to the green house to "grow" them to a size for planting. I bought a "full spectrum" Led fixture about 4 years ago and the light was really hard on your eyes and you could not see well with that light. I was glad when it failed after that first year as it did not root the dahlias any quicker and the light was annoying.

SteveM

I used to use the cheapo, cool-white fluorescent shop lights (from the big box stores) to root my cuttings but now I use the cheapo, cool-white LED shop lights (from the big box stores). The red spectrum isn't necessary for vegetative growth.

NCDahlia

I have my lights on a timer to turn on at 6 am and turn off at 10 pm. I do not use a heat mat (only for garden hard to germinate like peppers). I have 2 4-shelf, 16 tray light stands bought 10 years ago from "harris seed" probably is 3x what I paid back then with the inflation.

jistjul

NCDahlia Thanks! My lights are on a timer too. They come on at 6:30am and go out at 8:30pm

SteveM

jistjul 82º @ 50% RH should be close to perfect. I don't worry about it being too hot until it gets about 85º or above but that is under my growing conditions. The old saying "There are as many ways to store dahlia tubers as there are dahlia growers." also applies to taking cuttings. I have killed many, many cuttings learning and improving on what works best in my case. If you experiment you will soon find what works best for your specific conditions. Keep us posted!

bloomhjelm

Speaking of a million different ways. Some friends have suggested using a syringe to inject rooting gel into a rooting cube, instead of dipping multiple cuttings in the same plop of rooting powder. I only have rooting powder. I would like to try this, and am considering mixing it with aloe vera to make a "gel" though instead of buying a whole new thing of IBA in a different form. I can't think of any downside to this except taking my own time.

ksc

After numerous little experiments I've come to the conclusion that dahlia cuttings root despite using gels/powders, I also found some rooting products actually hinder rooting. I think that stable conditions in the right zone are far more important for quick rooting.

Teddahlia

We stopped using rooting hormones well over 20 years ago. We grow about 1,000 cuttings per year. They are done in batches of 36. After 12 days under the lights a typical batch has about 30 rooted. I define rooted as seeing white roots at the bottom of the small pot. Sometimes a couple rot. Sometimes a few do not root and they go into the hospital ward for unrooted cuttings. Most of them root but a few are just duds. Usually I have 4 or 5 pots with two cuttings in them and so generally get a full 36 from each flat.
I do cuttings off of tubers for 80% of them. I always do some leaf cuttings and it is fun to get plants from split stems. However, they take an extra 2 weeks of growing to be the same size as tuber cuttings. I do not mix white cuttings with regular cuttings and they are rooted in the hospital ward.
Would rooting hormones improve our results? I bet the leaf cuttings may benefit while the tuber cuttings probably not much. My big concern is the fact that rooting hormones are chemicals and my son the chemist always says if you can avoid exposure to a chemical, you are better off. So we avoid using the rooting concoctions and I do not have roots growing from my fingers.

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