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Twelfth Night is coming.....

What do we do with our Christmas tree now the needles are starting to drop? Well there's no needles that will drop from this beauty, but read on.

Every New Year it’s the same. So many of us seem to have the same dilemma. Now that Christmas Day and Twelfth Night have been and gone, what do we do with it? Do we leave it out with our wrapping paper and empty New Year’s Eve bottles? Do we take it to the recycling centre and throw it in that big skip with all the others? Or is there merit in trying to recycle them ourselves?

The other year we heard about how some people gather up all the needles that have fallen onto the carpet under their tree – and the rest that fall as the decorations are removed and the tree is taken outside – and then use them to create their own compost or mulch for acid loving plants.

And we started to wonder how much truth there is in that and if it works, or whether it’s simply a gardening myth. After all it sounds like it might be feasible and benefit plants that like acid soil but if it’s not actually doing any good then might we better off just taking the old tree and needles to the recycling centre after all?

So the first thing we did was have a look at a rather good book we were given a year or so back. It’s called Gardening Myths and Misconceptions and is written by the local no-dig advocate, Charles Dowding. We thought if anyone would know, then Charles would.

Alas we couldn’t find any reference to it in Charles’ book so we started to look a bit further afield and stumbled across an article that started with the premise that if your soil is alkaline – it has a pH value of 7 and above - and you want to make it more acidic then, as pine needles are thought to be acidic, then adding them to your soil will help.

Soil has a certain pH level which is expressed as a number between 1 and 14. A value of 1 is extremely acidic, a value of 14 is extremely alkaline and a value of 7 is consider neutral – neither acidic or alkaline.

So the first thing we’d need to establish is the acidity of our soil, and how much that matters in terms of the plants that we’re wanting to grow.

One way of establishing the type of soil you have is to buy a test kit. Typically, you get a small plastic container in which a small quantity of soil is mixed with some water. Then some powder or capsules that come with the kit is added to the mixture and, as the colour of the water changes it is compared to a colour chart. Oddly enough the kits don’t necessarily indicate the results using the blue and red that we might recall from our science lessons – but comparing the colour of that mixture to the colours on the chart will tell us whether our soil is acidic or alkaline.

Then once you know the pH value of your soil you can then determine the effects your type of soil will have on the plants you want to grow. Most plants like a soil that is neutral – a pH score of between 6.4 and 7.5. But - and it’s a big but – some plants will only thrive in certain types of soil. Azaleas and rhododendrons prefer acid soil and will start to look sickly if the soil is too alkaline. One tell-tale sign of having soil that’s too alkaline is that the leaves of those acid loving plants might turn yellow and eventually drop off.

So if we have plants that need acidic soils can those needles from our Christmas trees help? Can we use them to alter the acidity of the soil by, say using them as a mulch?

To test that we took a walk up through the woods by Longleat – where there are loads of pine trees – and we gathered up a few samples that we then brought home to test.

The first thing that we brought home were some green needles that we took from one of the trees. Then we brought home a bag of needles that were brown and that we had scooped up off the forest floor. We also dug up a small amount of soil from the foot of one of the pine trees. And then finally we dug up some soil from an area in the woods were there weren’t any pine trees.

Mixing each of those samples with some rainwater – we used rainwater as that was the most neutral source of water that we could find – we found that:

1. The fresh green needles were only slightly acidic,

2. The ones that were brown were mainly neutral and

3. That the soil samples from both areas – those that had pine trees growing – and presumably must have had years of needles falling – and those areas that didn’t - had no noticeable difference between the acidity at all.

So what does all of that actually mean? Well in terms of what we might do with our Christmas trees it probably means this.

Bearing in mind that your tree was probably cut down sometime ago then the needles you’ll have will be more brown than green. And – admittedly whilst not a strictly controlled scientific test – we found that brown needles are mainly neutral. So that premise that we started with – the idea that pine trees and their needles are acidic and can be used to alter the acidity of our soil is probably, at best, a bit fanciful.

Now that doesn’t mean that we can’t get some benefit from our pine needles and Christmas trees. The addition of any organic matter can help improve the structure of our soil and whilst it’s a good idea to be aware of all of the properties of your soil – it’s highly unlikely that a few branches of brown needles will have much of an effect on it’s acidity!


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