HelpfulGardener.com

Is there a chart that tells you the best temp per seed for sprouting? Does anyone measure the surface soil temp of the seed box that has a heat pad under it? What temp are the heat pads set too? Should a flat or seed box be covered with plastic or insulation while using a heat pad to preserve more heat in the box? It seems that a tomato seed will take 10 days or more to sprout at 50 degrees buy only a few days at 75 degrees!

I posted this once before, but here it is again:


https://tomclothier.hort.net/page11.html

scroll down a bit to the chart:

Percentage of Normal Vegetable Seedlings
Produced at Different Temperatures

so reading across the tomato row: (degrees F)


Soil Temp 32...41....50..........59.......68........77.......86......95....104
Tomatoes 0.....0....82(43)..98(14)...98(8)...97(6)...83(6)..46(9)...0

so at 32 and 41 deg, none of the seeds sprouted. At 50 degrees 82% sprouted, but it took them 43 days to do so (!). At 59 deg, there was almost complete germination by 14 days, at 68 it took 8 days and at 77 only 6. At 86 deg, it still took 6 days, but germination percent is beginning to decline again.

Of course YRMV, but this gives an idea of the effect of temperature on germination rate and percent.

Thanks Rainbow that is a nice chart and good to know!

Yep -- agree! I think I had a link to this on the old iPad but lost it in the transition to the new.
Thanks for posting it.

Its hard to figure in my solar greenhouse since the temp goes from 80 down to 30. The heat chamber helps! to many boxes to use a heat pad. The heat pad does not work on Styrofoam box and would get too hot and maybe burn out!

You need a soil thermometer. For seeds, the only temp that matters is soil temp. If you can keep the soil warm, doesn't matter what the air is doing.

I keep my germination grow room at 80. It has a space heater on a thermostat. It seems to me that most all seeds like 80 degrees. I sprouted Jalapeno peppers in 8 days this year!! When I was checking germination percentage I germinated green beans in less than 24 hours....