Autumn Colour Failure

There has to be a reason why two different nurserymen at two different arboretums said the same thing without hesitation and with full confidence that it will solve my problem.

The trees that i'm treating with sulphate of iron are behaving differently to previous years and differently from those trees i'm not treating.

 

I hope it works for you, but if it was such a good idea, I would have expected to have come across it before, in nearly 40 years of gardening, and I haven’t.
Lack of iron will make leaves yellow, rather than the normal green, which is what I think the people you spoke to were referring to.

 

The suggestion seems to be that only trees growing in acidic conditions colour up in Autumn, to be honest, I dont think that is true.

Some trees obviously may prefer acid conditions, but I would have thought they would have grown poorly and showed signs of chlorosis if they actually were not happy.

Just my personal thoughts but autumn colour is very variable in this country.

In what way are they different? Just interested.

 

Yes, previous years leaves were more yellow and this year's untreated trees are more yellow too. In previous years, new growth was also more yellow in colour only, no red or orange on new growth.

This year's treated trees have young leaves that are orange and red in colour firstly before turning a deep green, and there are more leaves that are smaller in size.

My question to the nurserymen at a number of arboretums last autumn was specifically, "Why are my trees not sporting red and orange autumn colour?" A discussion took place and a number of questions answered, resulting in a very confident conclusion by two different nurserymen at two different arboretums.

Not at all, it isn't true, but perhaps some trees and plants just need a little help where the soil is more alkaline. Perhaps Acers and Maples will grow and do well in all soil types within boundaries obviously, but perhaps to colour up well they need a more acidic soil type plus ideal weather conditions.

I don't know nor understand why, but i have to try something before i dig them up, which i don't want to do. If i don't get them out of the ground within the next couple of years, my chances of getting them out alive to sell on will be greatly reduced.

 

If the new growth in previous years has been yellow then I can well believe it is an iron problem.
Maybe your soil is very alkaline?

 

I'd agree with @JWK in that it's the trees you've chosen that's the main problem, as it sounds like your soil isn't suited well enough for them to thrive.
When I checked, Liquidamber prefers a more acidic soil too. Acers and Rowans grow extremely well up here in the west because the conditions and climate suit them perfectly. Plenty of moisture, cooler climate and neutral to acidic soil.

If Camellias, Skimmias and Azaleas are doing well, it may simply be that they're in a better site. It's odd that the Pieris isn't though, unless it's too alkaline for it. They all like similar conditions.
A photo of the other plants, and their proximity to the ones not doing well, would help with other ideas.
It's certainly not ideal to keep constantly adding a feed to soil in a border in order to help. A purpose built bed would be better, but that probably isn't viable.

 

If you want a general idea of your soil type and pH, have a look at this site which will give general details of the soil type in your postcode
LandIS - Land Information System - Soilscapes soil types viewer

My soil is slightly acid clay-based.
The big acer in my front garden has different autumn colours every year.
Sometimes they get to turn dark red before dropping, other years, it's orange and sometimes dark pink.
The soil is the same every year, so it can only be climate that makes a difference.
I've never mulched or fed the soil in that area.

Next door have a Liquidamber about 20ft and it does colour up nicely in the autumn, but I can't say I note what the colors are each year.

 

Yes -clay is perfect for acers @Pete8 as long as the drainage is good. The weather makes a big difference - timing as well as type for autumn colours, and it will change that colouring year to year if there are large variations. It affects summer colouring of Acers too.
That link doesn't cover Scotland, which is a pity.

 

@fairygirl similar thing for Scotland.
National soil map of Scotland | Scotland's soils

 

Thanks for that @NigelJ

 

I grow camellias and a scraggy looking Rhodo in the same bed, they have been there for years and should they get slightly yellow I give them one feed of chelated iron, not iron sulphate.
I'm not a chemist but my understanding is that alkaline soil locks up iron from ericaceous plants, just adding sulphate of iron slowly acidifies the soil, but you could just add sulphur as the iron is already there, its just that the plants cant take it up in alkaline conditions, sulphur in itself does the acidifying.
Chelated or sequestered iron would be freely available to the plants even in alkaline conditions.

 

Thank you to all those that have offered help etc.

Thank you for this link, very interesting indeed, and the website gives me a lime rich over chalk or limestone to the southern higher side of the garden and slightly acid on the lower northern side. My garden is more in the area of lime rich and on the side of a hill. Lime rich above, slightly acid below.

Guess where i planted my trees!!??