Grow Your Own Magazine

Am thinking of getting a small paraffin heater for my 4ft x 4ft glass greenhouse. Would the Parasene Super Warm 4 681 be suitable or would the smaller Warm Lite 499 heater be more appropriate? Or am I just wasting my time in a 4ft x 4ft greenhouse?

A lot depends on what you want to grow.
If you were just wanting to keep the frost off a small paraffin cold frame heater would do. I have one which I use in a partitioned section within my greenhouse just for frost protection. It is a parasene model (no idea of number). You can supposedly use it for 14 days without a refill but I tend to get a week from a filling.

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My Majesty made for him a garden anew in order
to present to him vegetables and all beautiful flowers.- Offerings of Thutmose III to Amon-Ra (1500 BCE)

If you put a small heater under a bench and your plants on top. of the bench. with some kind of cover (mini-greenhouse best , or fleece), you can grow in late winter and you can use a small heater.
If you want to heat the whole greenhouse, a heater that uses 5 litres/week is needed.

I have a 8x6 greenhouse: even when lined with bubblewrap and using a blueflame heater (4 litres in 3 days) in cold winter nights we get -1C inside the greenhouse ... so I use a minigreenhouse on top of a bench and heater underneath and raise temp on cold nights to 5C inside the minigreenhouse.

Of course these temperatures are so low as to be useless for tomatoes or anything tender.

mind you when we had proper winters some 10 years ago overnight frosts of -8C were not uncommon.