Tesco’s half-price Christmas trees could be sagging by Christmas Day if bought too early, a grower has warned, recommending that households wait until about a week before Christmas Eve to put up a cut tree if they want it to last until New Year.

As retailers launch their festive ranges, the advice is to keep trees cool, away from radiators and supplied with fresh water. Trimming the trunk can help water absorption, while spraying the foliage can also help keep a tree looking fresh. Different varieties offer different benefits, from the non-dropping needles of Nordmann firs to the longer lifespan of pine trees. But can any cut tree bought now really last the full holiday?

When to put up your Christmas tree is a question almost as divisive as whether Yorkshire pudding has a place on the Christmas dinner plate. Some might feel the best time is just after Bonfire Night, others may think Christmas Eve is more appropriate, and most will probably plump for somewhere in between.

Tesco started selling Christmas trees at half-price this week and said more than 90% of its trees had sold out by the end of November last year.

Lidl and some other retailers are also launching their ranges next week, while others, including Dobbies Garden Centres, are waiting until the last week of November.

But with Christmas Day still six weeks away, is it unwise to rush into buying a real tree so early? And do you risk spending Christmas week cleaning up piles of pine needles?

Probably, says Mick Walker, from Bolton Christmas Trees, which grows trees in the Scottish Highlands before sending them to homes across the UK.

“It might last until the beginning of Christmas, but it won't last the full holiday,” he warns. “Unless it's a potted one, it's going to be sagging by Christmas Day — big time.”

He calls Tesco’s half-price deal “insane”, adding that it is “sucking them into buying something now that isn't going to do the job”.

So when would he suggest is the best time?

“If it was me, I'd put it up a week before Christmas Eve,” he says, adding that it would then last straight through until New Year.

According to the Royal Horticultural Society (RHS), cut Christmas trees should usually last about four weeks with the right care, although some retailers suggest their trees can last between four and six weeks.

Tesco says its range includes both cut firs and potted spruces and firs, but that all its trees have care instructions on their labels that should “keep them looking their best right up until Christmas Day”.

It encourages any customer who buys a product they are unhappy with to return it to the store.

How to keep your tree looking fresh

Walker has some practical tips for keeping your tree looking good for as long as possible this Christmas.

“Keep watering it, spraying the leaves, keeping it cool, keeping it away from radiators in the coolest spot in the room,” he says.

In addition to Walker’s advice, Forestry England recommends giving your tree’s trunk a trim when you get it home. Sawing around half an inch (1.2cm) off the base will remove any hardened sap, allowing the tree to absorb more water, it says.

And have you heard the one about using cola or corn syrup in the base to help keep your tree alive? It’s a myth, tree experts say.

“Your beautiful tree just wants a constant supply of fresh water — it's that simple,” Forestry England states on its website.

Forester Richard Cooper, from Forestry England, says keeping a cut tree outside in a shaded area might help prolong its life. However, he adds: “It depends how keen you are to get it up and decorated.”

Keeping a potted tree outside and bringing it indoors for Christmas each year is also an option if you have the outdoor space, he says.

But trees in pots should be brought indoors “as late as possible — the weekend before Christmas is ideal”, advises the RHS.

“Do not keep living trees in the house any longer than 12 days but be guided by the tree. If it looks unhappy, put it back outside.”

How to choose the right tree for you

The most popular Christmas trees available in the UK are Nordmann firs, a non-drop variety, meaning they do not drop their needles.

Norway spruce is another common variety and has a strong pine scent, but should generally be kept outdoors or put up just before Christmas.

Pine trees, Walker says, have the longest lifespan, but he concedes that they lack that classic Christmas look.

Or, of course, you could opt for a tried-and-tested artificial tree, which is what Katie McDonald, from Belfast, put up in her house last week.

“When I was a kid my mum always waited to the last minute to let us kids put the tree up. We would be the last house on our street and the last of all our friends to get the tree up,” she says.

“So I made myself a wee childlike promise that when I had my own house I'd be one of the first to put my tree up.”

She says she will replace her artificial tree with a real one in a few weeks, so it is in prime condition come Christmas Day.

Meanwhile, Steve Chapman, from Merseyside, says the festive season for his family is all about traditions. While his children would not settle for just 12 days of Christmas, “it's certainly not two months of Christmas”.

His family always try to resist the urge to decorate too soon, so in the first week of December they head to a local farm that grows Christmas trees. They select one from the field and have it delivered the same day.

“There is nothing better than the smell of a real tree at Christmas,” Steve says.