Air, Rockwool, And Dome Temperatures.., which one is MOST important?

[Cesar Chavez]

Hello, I am trying to fine tune my temperatures for the germination process, using Rockwool Mini-Cubes, in a humidity dome, with heat mat and controller. I pulled out my commercial heat mat and began tinkering with the temperature controller. Set it between 74-75. I have a window temperature gauge inside humidity dome, and I have a Honeywell sensing probe also in there placed at seed level. Now onto my questions. I seem to be getting a few different temps. The Honeywell sensing probe ranges from 80.6-87.8, and when the sensing probe reaches its peak, 87.8, the window gauge registers 92-94. However, the meat thermometer placed in the rockwool stays between 77-80 the entire time. My air temperature outside of the dome is around 76. Which temperature reading should I be focusing on more? The probe and window instrument gauge? Or is the meat thermometer more accurate for seed germination? Thanks to anyone who may reply.

 

[smokingjoe]

Gotta be honest, I have cloned hundreds of plants and never bothered measuring any of those quantities. Ambient temp and humidity are normally in the appropriate range in my part of the world.

If you are in a colder enviroment you would need to pay attention to both. That said keep the temp right and the odd spray/mist from a spray bottle oughta take care of the humidity.

 

[Cesar Chavez]

I hear yuh, but I have had a horrible time getting seeds to germinate, whether in RW, RR, or soil. I have narrowed it down to temperature control. In the begining it was way to hot, and I burnt seeds. This last batch I think was too cold. After 41 seeds and only 6 plants to show for, I desperately want to get this right.

 

[smokingjoe]

Is the honeywell digital?

 

[smokingjoe]

How old are the seeds?

 

[Cesar Chavez]

Honeywell is digital. Seeds are from Attitude seed bank; shipped to me less then 2 months ago.

 

[Smokey Mcpotster]

First off I have only germed seeds once, a week ago. I got all 8 to pop in 48 hours. (beginners luck) When I started reading here I found a couple of posts that hit home for me. Keep it simple, Hippie in England or Hick made the comment that these seeds have been around forever. They got by this far without our help.
I took a 20 year old heating pad, turned it on low. I put my dome on a couple layers of towels and took readings for a day. I ended up with 5 layers of towels on top of the mat. This kept my temp between 77-81 degrees.I put my seeds in rockwool, kept the rw damp, mother nature did the rest. I kept a towel over the top, except for the 10 times a day I checked them, lol. The only temp I monitored was the air temp in the dome. I would make sure your dome has a stable temp for 10-12 hours before using it. To me the only temp that matters is the temp in the dome.
I know from life that you can make something simple way to f'n complicated (not saying you did). I would take a step back and look at other peoples methods. I read one that detailed how to germ the seeds in the rockwool. Most use the paper towel method, I just chose the one that made me feel most comfortable. Good luck to you, you'll get there.

 

[dirtyolsouth]

Hi,

I usually stick my tempstat probe into a rockwool cube, root plug or directly in the soil... whatever I'm using. That's going to be the most accurate gauge of the temp where the seed is. Be careful not to let things get too hot... I'd keep things under 85 personally but heat really does help seeds to germinate and roots to develop.

Also... humidity domes are great to use but only until they germinate. As soon as you get a few seedlings to show their heads above the cubes get the humidity dome off of their or you'll risk encouraging 'damping off' (root rot) and temps inside the dome could make them wilt or fry them.

Peace!