Monday, 9 May 2011

Using dead tree leaves for improving the soil.

I went down the allotment just to have a look.  I looked closely at the oca row - as is my want and believe it or not I found oca growing.  Makes gardening worth while.  I just hope that it does not get caught by the frost next week.  I will have to take a photograph of it.  My camera has gone phutt so the oca might get a little bigger before I can get a new camera and some photographs.  I might borrow one though - camera I mean not photograph.  The camera card still works just not the camera.  Not sure what I have done to it.  These digital ones cannot be taken apart and poked at with a stick to make them work unfortunately. Still the old ones did not really respond well when I did it to them.

Now I have just been asked again about using leaves on the allotment. All plants have leaves and tobacco leaves have an NPK (nitrogen, phosphorus, and potassium) of 4.0:0.5:6.0, while comfrey leaves have a NPK of 1.8:0.5:5.3. These are live leaves though.

If we confine ‘leaves’ to those of trees, there is a noticeable drop in their nutrient content, however they still do contain some nutrients. Oak leaves for instance have an NPK of 0.8:0.35:0.2 and apple having 1.0:0.15:0.4. Even pine needles have an NPK of 0.5:0.12:0.03 – not much but still better than a sharpened stick with nails stuck in your eye. Dead leaves would contain less nutrients.

The fact that tree leaves did not have many nutrients was noted by the Victorian gardeners because they used leaf mould to make seed compost. Seed compost needs less nutrient because the seed is mostly stored food and this is used in germination. The compost does not need great amounts of nutrient, however it does need to be open and friable and this is what leaf mould adds to a seed compost.  

Using dead tree leaves for a mulch could possibly remove some nitrogen from the soil but I would suggest that it does not remove as much as some people seem to think.  However, I would rather pile them up in a compost heap for a year and then use the leaf mould as a soil improver.  The majority of the rotting process has begun to slow down so less nitrogen would be taken from the soil.  

Lets face it any organic matter added to the soil will improve it.  

There is a toad in the greenhouse and a good job too.  No slugs.


  1. I find that if I mulch with dead leaves in the autumn, most of them have disappeared by the time things start growing again. Regardless of it;s nutritional content, it keeps the weeds down and builds up organic matter in the soil. When I tried digging in dead leaves, I found I was digging them up apparently unchanged the following year.

  2. I tend to agree with you Robert. I am coming to the belief that it is better to allow them to rot down before digging them in - whether through mulching or composting.

  3. Many home-owners here in Texas too lazy to tend their own gardens hire 'landscapers' (a euphemism for 'yard cleaners'), who use blowers to fully remove any mulch the home-owner had spread only the week before, because when it is covered in pine needles it no longer looks aethetically pleasing! I leave the leaves/pine needles in situ and simply cover them with the next layer of mulch that I have delivered. I've found that they break down over about 15 months, I have dark rich well-drained soil with an abundance of earthworms, but I cannot attest to the actual pH of the soil.