How to revive struggling hedge in poor soil?

[deborah1]

Hi. Been in our first home for 4 months now and trying to keep the garden going. I did a post about our yellowing lawn, which we are aerating, too dressings and fertilising as the soil has become compacted. I was wondering if we are having a similar problem elsewhere in the garden. 
The hedge has survived, but doesn’t look great. It is a Portuguese laurel (I think?) and the better one seems to have ok soil when I use my moisture measures, whereas the worst one seems to have very compacted soil like the grass has. How do I address this without further damaging the plants, or harming the roots? Also is there a reason this has happened and can I stop it happening again?

The garden had topsoil put on it everywhere, which looked like normal soil you would buy in a bag, but underneath I know the soil is poor and stony. It was apparently fertilised so I was surprised I might need to fertilise the lawn. Also unfortunately my father in law put far too much mulch on it, ‘mulch volcanoes’, and I had a newborn and no energy to remove the excess. Wanting to avoid further issues. Will not tell my father in law as not someone who ‘learns easily’ 🤣. 
Thanks so much! 
Deb
(picture of best and worst plants in question. )

observations for information:

worst plants: 

-more compacted soil

-wilt more on low cloud cover days especially, although all do

-wilt somewhat on hot days but worst on hot days with less cloud cover

-worst have more yellowed leaves on them

-daily watering has not improved them beyond this point, roughly an hour of ‘heavy rain’ amount of sprinkler, making sure all are covered by sprinkler well. On testing seems to be 10-14mm water in 1 hour delivered. 
- pattern of yellowing: not specifically outer most leaves, but definitely on sun facing side. Almost none on fence facing side. 
- east facing garden. 

 

[JacobZ]

Hi @deborah1,

It sounds like your Portuguese laurels are struggling due to a combination of compacted soil, poor drainage, and possible overwatering. The symptoms—worse wilting on low-cloud days, yellowing on the sun-exposed side, and lack of improvement despite heavy watering—suggest the roots might be struggling to take up oxygen.

Your watering schedule will more than likely need adjusting. Watering daily can contribute to shallow root growth and oxygen deprivation, so it’s better to water deeply two to three times per week, ensuring the soil has a chance to dry slightly between waterings. Check the dampness of the soil before watering again. If it is still wet, wait a day before watering again. To prevent future issues, continue monitoring soil moisture at the root level rather than just at the surface. 

To address soil compaction without harming the roots, start by gently aerating around the plants. Instead of deep digging, use a hand fork to poke holes in the soil, wiggling slightly to create air gaps. If your subsoil has a lot of clay, applying gypsum can help break up compaction over time without damaging roots. Adding a thin layer, around 1cm thick, of compost or manure around the base of the plants can also improve soil structure gradually.

Since you mentioned the issue of "mulch volcanoes," it’s best to pull the mulch away from the base of the plants, leaving a gap of about 5–10cm to prevent rot and allow airflow. Keep the mulch layer to a maximum of 5cm, as too much can trap moisture and worsen compaction.

Fertilising may not be necessary just yet, as the soil was previously fertilised. In some cases, too much nitrogen can stress plants further. If you do choose to fertilise, opt for a slow-release organic fertiliser to avoid shocking the plants and causing additional stress.

Gradually improve soil conditions with organic matter and aeration over time. Portuguese laurels are quite hardy once established, so focusing on deep watering and long-term soil improvement will help them recover and thrive. 

And don’t worry about mentioning the mulch fix to your father-in-law—some things are best handled quietly!

Let me know if you have any further questions.

Jacob

[deborah1]

Ah great! God I find watering so hard lol. For the lawn which is watered by the same sprinkler we have reduced the settings to the same amount of water but twice a week about a week or so ago. Sounds like that is ok for the hedge too? 
Out of interest can you explain the science of the yellowing on the sun facing side, and reaction to heat and low cloud cover days? I’m just interested. 
I’ll do the aeration and alter the mulch like you said and see where we go from there. 😎. 
thanks! 

[JacobZ]

Hi @deborah1,

You'll have to assess the hedges as you go, but deep watering twice a week sounds about right. With changes in temperature and weather conditions, this could be too little or too much, so check the top 5-10cm of soil for moisture before watering. If it is still wet, wait a day or two, if it is dry, water as you had planned. There is no strict schedule that you should stick to, so be flexible.

The wilting and yellow are due to a combination of stress from soil compaction, overwatering and the heat of the sun. 

Compaction reduces oxygen availability, making it harder for roots to function. It also slows drainage, keeping the roots sitting in water longer. In compacted areas, even though there’s plenty of water, the plant may still be struggling to take it up, leading to stress.

As the plant is already stressed and struggling to uptake the water that is available to it, this stress can be magnified on hot days, which will manifest in yellowing and wilting of the leaves.

Your focus with these plants should be on improving soil structure and finding a happy balance between enough water and not too much water.

Allow me to tag @Noelle and @mich1972 to see what they think and if they have any further advice they can offer.

Let me know if you have any further questions.

Jacob

[deborah1]

Thanks so much for your advice. I have done what you suggested and when I dug down I found 15-20cm of mulch and rock solid fine looking compacted soil underneath and shallow roots some above the soil line. The soil is almost impenetrable with a garden fork!  I scraped the mulch right back, so I now have mulch craters rather than volcanoes (thanks FIL) and found shallow roots like you said. I then added a fine layer of compost and very gently patted it down and decided I should lightly cover any roots. I also discovered around some of them ‘white lacy stuff’ amongst the wood chips. The garden and the mulch has been there for 4 months now. I wondered if this could be a fungus? I’ve tried to include a close up but don’t know how visible it is. I decided to remove any mulch that contained it just in case.

The sprinkler has been turned down to water twice a week, 10-14 mm at a time with additional watering on days above 30 degrees, and missing watering if it rains consistently the day before a similar amount. 
How does this sound? 
Deb

    

[MitchellMc]

Hi @deborah1,

It sounds like the planting of the trees was done to improve the look for sale and appropriates steps to improve the soil might have been overlooked. They really should be on 5-10cm at most of mulch and then good quality soil. The fact that the roots are on top of the soil is an indication that they're likely not deeply rooted. Removing the excessive mulch and replacing it with compost is a good first step.

The white stuff in the mulch is usually fungal mycelium, which is a natural and beneficial part of the decomposition process. Fungi break down organic matter, enriching the soil with nutrients. It’s common in damp conditions and often appears as white, thread-like strands or a powdery coating.

Mitchell

[deborah1]

Aha ok. So a beneficial fungus and nothing to be worried about. Yeah the mulch is very damp. Ok I will keep these things in mind and go around removing excess mulch, aerating the compacted soil and adding compost, or enlist help to do this. Thanks!