The Garden Community for Garden Lovers

Acid soil


By Cmalley

United Kingdom Gb

I have a very old well established garden, which generally has an alkaline soil with a ph of 6- 7. Over the last twelve months I have developed a problem in one corner where I noticed that my established hedge of lilac bushes were dying at one end. The end which is affected has a very large old conifer tree, which on close inspection is also not looking very well. It has lost most of its needles especially up the centre of the tree. This is all around the tree not just on one side and the ends of the branches are the least affected, so I do not think it is wind damage. This spring we did apply a mulch of well rotted horse manure over the whole of the front area, in an attempt to save the lilacs but to no avail. The lilacs at the other end of the hedge appear well and are putting out healthy runners as usual, they also had the manure applied this spring.

Having dug out the dead lilac bushes (three or four) and cleared the ground I tested the soil to find that the usually alkaline soil has become very acid in that corner (ph 4-5). However on the other side of the conifer and around the conifer it remains alkaline (ph 6.3-6.8). What is more I find that the deeper I dig the more acid the problem corner becomes (ph 3) as opposed to the rest of the garden (including around the roots of the conifer) where it becomes more alkaline the deeper I dig (7.1).

What is happening and what should I do?

Do I give up on the conifer and have it cut down?

Is there something I can plant, which will reduce the acidity of my soil in that area?

Will this problem spread?



Hi Cmalley well I know a great many people collect horse manure but live in a rural location and always been advised to avoid it and only use cow manure. Generally felt that horse manure very high in acidity - yes roses love acid content - but few others able to absorb high content.
Cow manure much gentler and more neutral due to their stomach network so their manure more processed.If you able to remove any do so or if all dug in could neutralise with garden lime.

14 Aug, 2008


Totally agree with Bonkersbon. My only fear for you is that your precious plants don't live long enough to enjoy their situation following his advice.

If I was in your place and the affected lilacs were 'irreplaceable' I'd be inclined to 'wait and see' for now, but if it looked like I was going to lose a highly valued plant I would dig them up. It's a big job, but 'doable' by one person for plants up to about 8ft high and when you've nothing to lose . . . . . .

15 Aug, 2008


My only problem with this answer is that the whole area was covered with the same manure and yet only an area (about 10%) has become acid the rest is very alkaline and happy. The remaining Lilacs are fine. What should I do? Manure is well dug in and I can't understand why the deeper I dig the more acid the soil becomes in this corner

15 Aug, 2008


It could be that the lie of the underground soil layers is creating your ponding effect in the 10% area. It could even be a land drain you don't know about yet. All of which is being exacerbated by the amount of rain which is also tending to accelerate the leeching of your manure.

The easiest/cheapest method of gardening is always to work with mother nature. Unfortunately, you went ahead with the horse manure and what's done is done.

You could either dig out the manure which, according to your post is causing your problems and highly likely to cause more in future.
Or you could adapt your planting with some acid lovers like I've done in my own garden. - My ground is acidic but in the three areas I've found to be bordering neutral/alkaline I've planted lilacs!

16 Aug, 2008


Thanks for the advice all. I think the possibility of an underground drain may well be the cause rather than the manure since the dying plants problem started long before the manure and if anything improved slightly for about a month after the manure. Will acid lovers increas or decline the acidity of the soil?

16 Aug, 2008


I don't think they put anything back into the soil, rather, they draw out what they need! So alkaline lovers would draw out the acid and not thrive to the point of dying off.

16 Aug, 2008


I live in an area with acid soil...I sweeten my soil with soil sweetner every fall to keep my not acid loving plants happy. why not sweeten the soil for your lilacs there?

20 Sep, 2008

How do I say thanks?

Answer question


Related questions

Not found an answer?