soil temperature variation with depth in a bulb garden

David Pilling
Wed, 20 Nov 2013 08:47:08 PST

In message 
<>, Chad Schroter <> writes
>If bulb chill hours are similar to fruit tree chill requirements - then 
>the hours at or below 40 are important. Growing at a greater depth may 
>actually reduce the chilling hours since the daily lows would be 
>averaged out.

That's the key do bulbs respond to average temps or peaks.

I did a similar experiment here (North West England, zone 8), it showed 
that temps above ground could be sub zero C for 24 hours or more, but 8 
inches down they would be above zero C.

Old conclusion, bulbs in the ground are safer than those in pots.

You can see my temperature logger results below and above ground for 
Winter 2012-2013 [1].

Here the problem is keeping bulbs warm, for Gastil it is the opposite.

In Winter, days are shorter than nights, on average things should be 
cooling down. One expects the temperatures below ground to lag and 
smooth out any short term fluctuations.

So on average temps underground should be higher. But bulbs may respond 
to the peak higher temperatures which will be lower underground.


Sensor above ground:

Sensor 8 inches down:

or as text

David Pilling

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