Temperature & the time it takes different seeds to sprout!

[Bobberman]

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!

[rainbowgardener]

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.

[Bobberman]

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

[applestar]

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.

[Bobberman]

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!

[rainbowgardener]

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.

[IndyGerdener]

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....