My Lily crop needs HEAT

[Michael Layman <layman@utahlinx.com>]

Request for advice,

My Lily (Lilium longiflorium) crop is just reaching Visible Bud.

Height is on the tall side so I am trying to control with a 
negative DIF.

The greenhouse is primarily heated by a hot water system with a 
gas forced air heater for backup.  Unfortunately, the boiler is
down for about 10-14 days awaiting a new heat exchanger :-(

The unit heater is not keeping up.  I would like 68-70F Nights,
but can only maintain about 62-64F and the soil temp is 54.

So the question is:  If I put an unvented propane space heater in
the house will I run a greater risk of damaging the crop with gas than
trying to catch up on timing later?

Or shall I run up the day temps and have the tallest crop in the west?

Thanks for any and all opinions,

Michael Layman
layman@utahlinx.com