Making soil more acidic for hydrangeas

[Bea1985]

Hello all,

I've a 4 year old climbing lace cap hydrangea and it has only just started to flower this year - but only grew two flower heads!

It's about 6 by 8 feet and is very healthy and leafy. I've read that they are encouraged to flower in more acidic soil. Ours is clay soil so I suspect quite alkaline.

I've also read that you can feed/ water the surrounding earth with something acidic to change the ph...

Trouble is I don't know what I should be using for this ? Anyone know of a soil acidifier ?!

Thanks!

I don't know about hydrangeas because mine are basically in sand (live by the coast) and they flower like billy-o but I was told coffee grounds on blueberries does the same thing.

I saw in the garden centre the other day you can buy a product that will make the soil more acidic to turn hydrangeas blue. It wasn’t expensive.

Once managed to change the color of a mop head hydrangea with coffee grinds. They will definitely make soil more acidic. You could also get some soil improver from the garden centre.

Hydrangeas aren't that fussy re soil but they need to be kept watered. They are thirsty shrubs.
In clay (alkaline) soil you won't get blue flowers. Even if you plant a blue hydrangea if you've got alkaline soul the following year it'll have dark pink flowers.
If you have acid soil your blue flowers will stay blue.
Obviously white and lighter pink hydrangeas will stay true to colour whatever the soil.

You can put peat down, a vinegar and water solution, ericacous soil. There is a good website with info but I can't link it.

You need ericaceous soil. My mum told me. I'm clueless but we just planted some in my border and she said don't need it unless I want blue flowers

The th a site and also gardeningknowhow. Can you replant somewhere else and start from scratch or into a really large tub or half barrel.

Hello all thank you,

It's a white flowering lacecap climbing hydrangea that's climbing up the house ... sorry if I was not clear.

Looks like coffee / vinegar solution could work. I will google soil improvers but don't really know where to start lol.

We also have a pink flowering hydrangea which is rather was blue so when I decide what to do I will give it the same treatment'

Think this will do:

Westland Sulphate of Iron Plant Food for Ericaceous Plants, 1.5 kg https://www.amazon.co.uk/dp/B001P3SMJ2/ref=cmswwrcppapi_rgKuBb67N9FRY

Yes, its also cheaper in wilko, they also do,their own brand half the price.

My grandma always used to put dregs of teapot on hydrangea (tea is acidic) to change colour. Don’t know if it worked. As I was only little

I was discussing this with my father this weekend as we've been to Devon where all the hydrangeas are pink whereas ours are purple/blue. Apparently his parents used to put bits of copper and old razor blades in the soil - that was probably the 1940s though so perhaps not quite the thing to do now!!
I prune ours pretty vigorously - back to the lowest bud - and that doesn't do ours any harm either.

Razor blades - aluminium ? The soil improver I bought I aluminium based ....

My mum used to put old Brillo pads under the hydrangeas. IIRC it made them turn blue.

I have a climbing hydrangea, also creamy white lacecap (petiolaris?) that did nothing for about 4y. Then I started watering it in the summer and it started growling and flowering like mad. I think I must have planted it too close to the wall and it was in a rain shadow.

I've installed a sophisticated watering system under it: cut the bottom off a 2L water bottle, pierced a few holes near the neck, screwed the top on tight, and buried it (top-down) about 1/4 of the way into the soil near the stem of the hydrangea. I fill it every time I water the plant, and only water if the bottle is empty.

I haven't fed at all.

Sulphate of iron, the cheapest and possibly most effective soil acidifier. Buy it as a powder on eBay, dissolve in hot water and water the soil. Don't get it on paving as it will stain. Commonly used to acidify turf in winter. Helps control moss.

https://www.rhs.org.uk/advice/profile?PID=122

White hydrangeas should stay white whatever you put on them. For coloured flowers, there are two factors. Available aluminium is what is required for blue flowers - so (a) you need to have aluminium salts in the soil and (b) acidic, the Al isn't available to the plant at neutral or alkaline pH.

If you got something like aluminium sulfate that should do both, I think OP. Iron sulfate is commonly used for acidicifying soil for ericaceous plants such as rhododendrons- if your soil naturally has aluminium then that would be all you need.

OP climbing hydrangeas are always white, they are a different variety from the shrub and you won't get one to turn blue or even pink no matter what you do, whether you bury it in it iron filings or do a naked dance around it painted in woad - it will remain white.

do a naked dance around it painted in woad - it will remain white.

Unless the woad rubs off you I guess

The climbing hydrangea is white and happy for it to be white , would just like it to flower!

Have a second non-climbing hydrangea which is pink and I'd prefer it to be blue.

My hydrangeas are all short of flowers this year.