PUTTING OFF-GRID GREENHOUSE HEATERS TO TEST

As the days get colder keeping your precious plants warm within the greenhouse becomes more of a challenge. But what can you do if there's no power on your plot? Here KG takes a look at four heaters that could help to keep things growing through the winter days...

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When the nights turn cold, keeping your greenhouse frost-free can be tricky – especially if there's no power supply on site. We tested four off-grid heaters to see which can take the chill off a greenhouse, polytunnel or cold frame, using only paraffin or bottled gas.

Most allotments and garden plots have no electricity, and running outdoor cabling is expensive, potentially unsafe, and often not allowed. For many gardeners, paraffin or gas heaters remain the only practical option for keeping frost at bay.

To find out how today's models perform, we ran a series of overnight tests using four popular heaters - three paraffin and one gas - in real-world conditions. Tests took place in a 6x3m polytunnel, a small hexagonal greenhouse and a double-glazed cold frame with a 3cm vent along the front edge.

Although conditions were unseasonably mild, what matters most is the difference between inside and outside readings. Each heater was judged on its temperature 'uplift' - how much warmer it kept the space compared with the ambient air.

In colder weather the same differentials would apply, though fuel use would inevitably rise. During the second set of tests, rain arrived in the early hours, briefly lifting outdoor temperatures and narrowing the gap between inside and outside readings - a realistic reflection of British autumn nights.

CRAZYGADGET® LARGE PARAFFIN SUPER WARM HEATER - SINGLE BURNER £19.99