Soil Temps: What's too hot?

AZRuss · May 27, 2009

I want to plant out some seedlings (determinate varieties mostly) for a mid to late November fall harvest. I have calculated that I need to do this at least by mid August for any chance of success. Air temps here August through mid September are 95+ day and 75+ night.

I use SWC's primarily. Yesterday I checked the soil temperatures in SWC's that contain fully mature tomato plants, and the temps ranged from 85 to 95 degrees. It's only May. I can expect that the soil temps will be at least that at plant-out time. (This is in white SWC's with white plastic mulch.)

Will seedlings grow in soil that warm?

dice · May 28, 2009

>90F is detrimental. They might make it anyway and merely
underperform at this early stage of development. This document
comparing soil temperatures, etc with different mulches has a
note on "maximum soil temperature":

http://www.public.iastate.edu/~taber...0/redmulch.pdf

AZRuss · May 28, 2009

dice,

Thanks for the informative article. I am going to start taking steps to reduce soil temps by insulating each SWC in white styrofoam. I did a test yestereday and it really works.

Also, interesting to note that clear plastic mulch produced the highest soil temps--very useful information for next February's plant out.

amideutch · May 29, 2009

Russ, have you thought about burying your SWC's in the ground? Dig a small hole equal to the height of your SWC's and take a temperature reading at the bottom of the hole. And since drainage is not a big player with SWC's you shouldn't have any problems. Ami

travis · May 29, 2009

Drainage could become a concern in a SWC if buried in the ground since the overflow drain hole may become bocked.

However with some precautions to accomodate the drain hole and by rigging a float gauge (maybe a ping pong ball superglued to a stick and stuck down the fill tube, or some such thing), I guess you could bury an SWC and monitor the water level adequately.

May 27, 2009	#1
AZRuss Tomatovillian™ Join Date: Nov 2008 Location: Tucson, AZ Posts: 171	Soil Temps: What's too hot? I want to plant out some seedlings (determinate varieties mostly) for a mid to late November fall harvest. I have calculated that I need to do this at least by mid August for any chance of success. Air temps here August through mid September are 95+ day and 75+ night. I use SWC's primarily. Yesterday I checked the soil temperatures in SWC's that contain fully mature tomato plants, and the temps ranged from 85 to 95 degrees. It's only May. I can expect that the soil temps will be at least that at plant-out time. (This is in white SWC's with white plastic mulch.) Will seedlings grow in soil that warm?

May 28, 2009	#2
dice Tomatovillian™ Join Date: Jan 2007 Location: PNW Posts: 4,743	>90F is detrimental. They might make it anyway and merely underperform at this early stage of development. This document comparing soil temperatures, etc with different mulches has a note on "maximum soil temperature": http://www.public.iastate.edu/~taber...0/redmulch.pdf __________________ -- alias

May 29, 2009	#4
amideutch Tomatovillian™ Join Date: Feb 2006 Location: Germany 49°26"N 07°36"E Posts: 5,041	Russ, have you thought about burying your SWC's in the ground? Dig a small hole equal to the height of your SWC's and take a temperature reading at the bottom of the hole. And since drainage is not a big player with SWC's you shouldn't have any problems. Ami __________________ Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘...Holy Crap .....What a ride!'

May 29, 2009	#5
travis Tomatovillian™ Join Date: Jan 2006 Location: Evansville, IN Posts: 2,984	Drainage could become a concern in a SWC if buried in the ground since the overflow drain hole may become bocked. However with some precautions to accomodate the drain hole and by rigging a float gauge (maybe a ping pong ball superglued to a stick and stuck down the fill tube, or some such thing), I guess you could bury an SWC and monitor the water level adequately.