Griselinia Problem

philip_bryant · July 2023

Hi all. I am new to the forum but desperately need some advice and help please.
We have a well established Griselinia hedge. Half of it is struggling.

There are dark patches and dark spots on some of the leaves and there were dead branches.

I cut away the dead stuff about a month ago but the hedge is still struggling on that side.

I read it could be leaf spot or root rot. The roots look fine. They aren’t soggy or mushy so I don’t think it’s that. I’ve freshened up the soil and dug around gently to aerate it just in case.

If it’s leaf spot I’ve heard you can spray it with a bicarbonate soda mixture (1/2 teaspoon to 4 litres if water) but I didn’t want to do that until I’d asked someone first.

The garden centres thought it was a burn but I’m not convinced. We are watering but not too much. In years gone by, we have never had to bother. It is in a mixture of sun and shade and there is a row of conifers behind it.

The right hand side of the hedge has the odd mark on the leaves but seems to be healthy.

Any suggestions or advice would be very much appreciated.
thank you!!

GardenerSuze · July 2023

@philip_bryant I wonder if it is weather related. Many shrubs are suffering with various leaf spots this year. Griselinia does like good air circulation.

Mrs-B3-Southampton,-Hants · July 2023

Mine couldn't have more air circulation if it tried! They also had the same sort of problem a while ago and I just snipped away all the dead stuff and it's fine now.

Fairygirl · July 2023

I'd also think that the conifer hedge is starting to have an effect.
Unless you're in a reliably wet area, the conifer will be taking up all the water and nutrients. It's very difficult to have two hedging plants so close together, and have both thriving.

Plantminded · July 2023

I'd say it needs watering, deeply. Applying a mulch of organic matter to the soil will also help to retain moisture. I grow a lot of Griselinia, as hedging and as specimen shrubs. They shed leaves selectively when the soil dries out. I have a 5 foot hedge of it growing less then 2 feet away from my neighbour's laurel hedge and it's been fine for nearly 10 years, but the bed gets watered occasionally for the other shrubs and perennials nearby. This photo was taken in early spring.

Image: https://us.v-cdn.net/6030279/uploads/editor/sh/8d5m0xm0p1ch.jpg

Plantminded · July 2023

Looking at the photo of your hedge again @philip_bryant, the area on the left looks as if it overshadowed by the conifer hedge more than the area on the right, restricting rain falling to the root area as well as the amount of sunlight it receives, both factors will cause differential growth. Some light pruning to achieve the same level across your hedge will also help, along with regular deep watering until there are signs of recovery, but don't apply any feed to the area at the moment.

philip_bryant · July 2023

Hi all. Firstly thank you so much for your comments and advice. It is very much appreciated.

The weather could well be a factor. We had a particularly nasty cold snap where snow lay on the ground back in December. That caused a winter burn on my box hedging and I know it affected other hedging in my area.

I did notice in spring there was quite a significant leaf drop around the Griselinia and a powdery mildew on the bottom leaves which I cut away.

Regards the conifers, they have been here for at least 40 years and the Griselinia about a decade and have always lived well together. Some of the Griselinia has probably been here longer as it pre-dates us in the house.

The canopy of the conifers is pretty much the same throughout, if anything it is probably thicker on the right where the Griselinia looks healthy.

The soil down there does get wet in the winter and dry in the summer but I’ve freshened it up and I can still feel a little moisture there. We have tried not to over water. It does sit in sun and shade.

My question now is what to do?

I can put mulch down and water more

or I can add some feed to the soil. I put some Levington’s Growmore around the Griselinia plants in Spring but could do that again and water in.

or if it’s leaf spot, I can spray with a bicarbonate mixture but I was a little hesitant on that.

Or I can cut away the dead stuff and affected leaves and hope it recovers on its own accord.

Once again any advice would be gratefully received. Thanks again

philip_bryant · July 2023

apologies just bumping this thread in case my reply or answers to the comments shed any more light on the issue.
as always, any advice gratefully received.
best wishes

Fairygirl · July 2023

I'd just say - snow isn't a problem. It's wet then freezing that causes problems, or long term frosts - ie a week of minus ten [or similar] and below.
Unless you live north of me where there's feet of snow lying for weeks at a time, it really isn't the cause of damage, other than when it lies on stems or branches which would break from the weight. I usually brush it off anything susceptible if there's more than about 3 inches.

Don't feed it - that's not helpful to any plant that's struggling.
Just trim it as suggested, remove and dead/dropped foliage from around it, and keep adding organic matter to help the soil.
Powdery mildew suggests dryness, so improving the soil will hep retain moisture but maintain drainage through wet periods.

philip_bryant · July 2023

thank you so much. I will try that.
I presume the idea of putting a bicarbonate soda mix for leaf spot is not advisable either?
to be honest I’m not sure it is leaf spot so I don’t want to exasperate the problem.
thanks again

Wayside · July 2023

I had tops shrivel and blacken when in full sun. At a high point in the garden, that's pretty much impossible for me to water. It's literally on rubble. Also the same blackened result when the frosts hit it. And I'm in SE England.

I lost a Dixon's cream in the winter. But we did have some long frosts.

Griselinia Problem

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