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Tomato heating cable

Hi Stan.... Underground electric cable heaters have been used by commercial
greenhouse growers in New Zealand, but I don't think the practice was
widespread. However, I suspect any lack of interest in the system would
most likely be linked to survival instinct rather than any ineffectiveness
because our domestic electricity is rated at a rather lethal 230 volts.

Just a few points that might help with your quest for the elusive early
tomato. 

Optimum air temperatures are 13-15C (56-59F) by night and around 18-19C
(65-66F) by day. Big swings between night and day, as experienced in early
Spring, have an adverse effect on the way tomato plants grow and certainly
reduces cropping.

More importantly the soil temperature MUST be 15C (59F) or higher before
you plant, otherwise root growth is restricted and an insidious form of rot
sets in that eventually cripples the plant after much wasted effort.

The other issue to consider when going for an early tomato crop is the
amount of light that is available. I don't have a definitive measurement
for you except to say they need lots of good bright light to do well. If
you provide bottom heat without enough light the plants grow leggy and the
lowest flower truss might form 3 feet up the stem.

Having said that, it is important to realise you are unlikely to ever meet
all these requirements totally. I would never be able to plant a single
tomato given strict adherence to these requirements, but I know when
conditions are likely to get as close as they ever come to them and I have
my seedlings ready to plant then.


Regards  Ian Gill
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