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Hi I received my first lot of plug plants from suttons yesterday Potted them up into 70-90mm pots all bedding plants impatients petunias lobelia. Their instruction were for 15-18 degree ideal heat to grow on but I only have 2 paraffin heaters in my 8 by 6 greenhouse . I live in the scottish borders and it was minus 2ish through the night outside When I checked in the greenhouse was 6-7 If I maintain this temperature at night and hopefully warmer through the day will the plugs be ok ? This is my first time with plugs and my first year with a greenhouse Any advice would be very welcome. Thanks Mike.

Yes I think so, the soil temperature may be slightly higher, freezing is the real problem, with the sun out my greenhouse rapidly heats up to t-shirt weather even with it being cold outside. We are already at 13 hours of daylight so as the nights shorten the plants will be at less than optimal temperatures for a shorter time.

I'm not a biology expert but isn't it photosynthesis that drives a plant to grow? so logically it hasn't much to do at night anyway so as long as its warm in the day when its most active they should do fine.



Mike. i really wouldnt put them out yet unless you can guarantee temperatures above 10 for 24 hours a day. The light in the greenhouse is good but I think you will struggle with the temrature. Keep them inside


Mike, I have been potting up plug plants from mail order for years and putting them in my greenhouse. They arrive end of March. For sometime I used one parafin heater with two chimneys (Parasene). Now My OH has rigged up an electric supply and I have a small electric heater. It just keeps it above freezing and frost proof when the temperature outside is -3 or -4°. Of course, during the day the temperature is a lot higher, especially when sunny - then it's in the 20s. Your 6° - 7° is warmer than some nights in my greenhouse. The important thing is that they don't freeze and that they have enough light. Without enough light they will go leggy. The daytime warmth will be enough for them to grow.


I dont want to start an argument but with the weather we have been having and some suggestion that it may last another few weeks, plus your location in the Scottish borders I think you may be courting disaster having tender bedding in the greenhouse.


Hi Mike2li

Your plants should be O.K. with the parafin heater but make sure you provide adequate ventilation,open doors during the day when temperatures lift, obviously turning off heater.

Regards and good luck

Mike W

Hi and thanks for all the replies
They will need to stay in the greenhouse as I have nowhere else to put them
I potted up the rest when I got home from work tonight and have roughly 200 .
The green house was 9-10 without the paraffin heater and the door left open a couple of inches all day from 7am.
Going to light a couple of candles from asda
Giant tea lights with a 9 hour burn time with paraffin heaters
I'm sure they were ??2 for 10 , bought a few pack weeks ago when I read somone recommend lighting cheap candles as frost protection.
Anyway thanks again for the replies .
I really enjoy reading all the gardening experts comments and helpful advice for the novice gardener like me

Hi Mike2li

A word of warning ,you are going to get a lot of soot from candles which will mess up your G.H.


Mike W


Referring to the title of this thread, there are now frost proof petunias out there

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