They are one of the most popular ways to grow delicious fruit and veg for longer without worrying about the extremes of the British weather.

But gardeners who have a greenhouse in their garden are being warned that they still need to prepare for the upcoming cold snap, which could cause chaos for seedlings and crops over the next few days.

The Met Office is forecasting snow for parts of England on Saturday, with a yellow weather warning for snow and ice in some areas of northern England, including Newcastle, York and Leeds.

Even in other areas of the country, temperatures are set to plunge again.

Gardeners often assume that greenhouses will protect their plants even in colder conditions but if the temperature drops below 5C, as it is forecast to for much of the UK on Saturday and Sunday, everything in your greenhouse could be killed off.

A spokesperson for GardenBuildingsDirect.co.uk said: “The weather at this time of year is very unpredictable and temperatures can dip suddenly. But being prepared means you have every chance of saving tender seedlings you’re nurturing in the greenhouse.

“There are some simple ways gardeners can make sure the greenhouse is warm enough. Filling small cracks and holes is a quick fix which will make a big difference. Covering plants with fleece and bubble wrap are both cost effective ways to keep them warm.

“On very cold nights, think about covering your plants with horticultural fleece to give them added protection. Remove it during the day so plants get the light and ventilation they need.

“Applying bubble wraps to windows and pots inside the greenhouse is a good way of keeping the heat in. It’s also a cost effective option.”

The Met Office says in its forecast: “Outbreaks of rain, sleet and snow are likely to develop early Saturday before easing from the west during the afternoon. Snow is more likely to the east of the Pennines, particularly above 150 metres, where 2-5cm may accumulate over the North York Moors and Northumberland.

"To lower levels, any falling snow may struggle to accumulate though some places may see up to 2cm before gradually easing during the afternoon. There is also a risk of ice over the Pennines, particularly above 200 metres where freezing rain is possible.”