semi-permeable membrane - harmful?

Hello - yet again I had a lot of large trees and shrubs planted 18 months ago and put down semi-permeable membrane covered in bark. It is a very large area and I didn't want to be weeding every few minutes. Only one of the trees has done as expected and a couple of the shrubs. All the rest look sick or just aren't growing. I have kept watered and have fed with Phostrogen a few times this year. I wondered if it could be down to the membrane as I have never had these problems before.

I have lifted the membrane from a section of the planting to see whether the trees and shrubs there start to do better. The ground underneath looked quite compacted but I did not loosen it as I didn't want to harm the roots that were quite visible on the surface underneath and raked the bark back on top of the soil. I wondered what your views on using membrane were.

Thanks!!!

 

I think the semi permeable membrane approach should be fine.

It should keep the roots more moist than bare soil.

I would go for something biased towards Nitrogen when feeding trees / hedges, to get them under way, and Phostrogen is biased towards Potassium / Potash. But having said that, its definitely better than nothing!

I plant all trees / hedges with a good scoop of Bonemeal (very biased towards Phosphate) in the planting hole to stimulate root growth.

Wind on the leaves might be stressing them - causing them to transpire and have to work harder to drink enough! - and some shelter might help if that is the case.

But ... if planted 18 months ago they had last year as their first season - wet and not very hot - ideal first year weather - and thus I would expect them to be making some progress this year.

 

If most of the roots are clearly visible at the surface, could that not suggest that the subsoil is too hard for the roots to penetrate properly?

When I was on holiday in Cornwall last year we visited an orchard that doubled as a research place. There were info signs all over. On one I remember reading it said that their first attempt at planting one area had failed miserably. They pulled the trees out, roots and all to find out what was up, and found that none of the roots had penetrated the subsoil. They replanted the area having first dug much deeper to loosen the subsoil, and the new trees had fared much better.

 

I've used membrane under trees and shrubs Silver and they were fine so I think the prolem lies elsewhere - if there is a problem. Maybe they just need time to get established and get going.

 

18 months ago would take us to the winter before last. Winter is the best time to move trees, and 18 months should be ample time for them to settle in. Of course it is likely that they'd be extra thirsty for a while until their roots have developed well, but my money would be on the soil conditions, either not enough nutrients or water retention, or subsoil to hard to penetrate so the roots have to grow close to the surface and compete with the roots from neighbouring trees.

 

Thanks everyone. The ground was thoroughly rotovated before planting - but the soil does now look compacted at the surface. The area was down to grass before this. I do wonder if this area could be subsoil dumped while building the house as the garden slopes upwards. As I said - I have removed a section of membrane - the bark is starting to rot down anyway and I hope will provide a good mulch on top of the soil which will hopefully help. I will see if the plants in this section start to do better than the others. I think however, that a soil test might be in order.

Some of the problem I guess is in planting very large mature specimens which will take more time to become established.

 

Membrane is a total waste of time, ditch it and add a thicker layer of bark, this will actualy retain moisture and improve the soil due to worms etc that will incorporate it as it breaks down.

 

Hi Silver,

I have no time for membranes myself-waste of money and effort and I do think they compact the soil more than necessary-but that's isn't what I think is the problem with your trees and shrubs.



How mature were the plants you put in? The more canopy the more needs it places on the root system.


I read you have had advice already about thoroughly digging over-really deeply and I agree-there could be hardpan of rubble or clay down there and the roots just can't break through it easily, couple that with the fact that trees and shrubs of a good size really could do with not struggling any more than they have to considering they are new in ( haven't grown to adapt to the conditions) and you have some problems.


Once you know the structure of the soil you can begin to discount the more obvious problems-too little too much moisture etc.

 

"could be hardpan"

Particularly if the site was formerly agricultural fields.

I lived in a house that had been built on a field some 15 years earlier.

We dug a trench for a hedge and 1 spit down it was solid. We had to use a pickaxe to get through the plough-pan :(

Thereafter I used a JCB to make flowerbeds, the barrier between the top spit and the soil below was so hard :(

 

The soil is very fine and light - very few stones, at least within the top couple of foot. It does compact easily. Last weekend I dug down a couple of foot to put a screen in for some climbers and although the top was quite wet where I had been watering, deeper down it was dry. Water does not seem to percolate down very well. Having said that, the more I water a couple of the conifers the worse they seem to be and have started turning yellow around the bottom again, so I don't know whether this is down to over watering or under watering.

The trees were all about 5 meters in height when planted. Some pot grown and some bare rooted. The bare rooted trees were silver birch and hornbeam. One birch has done very well but the others are struggling as are the pot grown leylandii and thuja. Strangely enough one tree I thought wouldn't succeed at all was a 5.5 meter high acacia but it is also doing well while the birches struggle

Again, thanks for help and advice.

 

"The trees were all about 5 meters in height when planted"

Conifers too? That's big for a conifer being moved, I think I would want a large root ball with that.

Deciduous bare-root transplants at that size take more easily.

"the more I water a couple of the conifers the worse they seem to be"

I soak newly-planted trees once a week. 2 minutes hose running each - I guess that is about 5 gallons, maybe more. (I have put a metre of slitted draining pipe around the rootball underground, and water into that so it reaches the roots and encourages them to do down).

Watering them more frequently than that, particularly given that they are 18 months old, shouldn't be necessary IMO