Yes. Definitely acid soil plants. I can't grow them either.

I'm surprised the botanical garden can grow them at 6.5. They may very well be acidifying the soil.

They're not acidifying but the Pieris there are only straight japonicas, which may make a difference. They have four large specimens all grown from seed planted from 1992-96, in different parts of the garden.

Thx!

A pH of 6.5 is fine, although an iron supplementation at that level may be necessary. Pieris of all sorts grow like weeds here in the PNW (one of my favored fall-back garden workhorse plants for design clients) and our soils are typically only slightly to moderately acidic (6.0-6.5 usually).

But alkaline soil will not work :-) I'd suspect the heat of CA as well as lack of water may also have a role.

have you considered calling the arboretum .. and asking for the head gardener .... and simply asking???

teaching is kinda the whole point of arboretums.botanical gardens ...

i found the local hidden lakes gardens guy actually .. very talkative ..

in the olden days.. you would leave a message .... and the darn gardener wouldnt even know how to use the message machine.. let alone the phone.. lol.. but with cells these days.. you might be connected right to him ... ya never know.. if you dont try ...

ken

That's an easy plant to go crazy over; I love them, too. I'm remembering from somewhere a rather terse description that sticks in my mind : "absolutely intolerant of alkaline or neutral soils ".

Even if you can provide all of the other basic requirements, I think that the pH issue trumps it all. The botanical garden lucks out with its acid soil, even if mildly so.

Thanks all - you have answered my question. I was afraid that was going to be the answer!
Ken I volunteer at that bot garden and the director is the one that gave me the info about their soil pH. He just wasn't sure about how intolerant the genus was of mildly alkaline soils. As confirmed above, very!

In general you can assume Ericads must have it acidic unless known otherwise. Obvious exceptions there madrona and manzanita.

And as a rule they can be expected to be prone to root rot, needing a cool, well-aerated soil. Even up here - where it is overcast or partly cloudy 10 months out of the year - many plantings display problems due to unsuitable rooting environments.

Even on extremely rainy Yaku Jima the pieris grow along streams, which they poison. They must water a lot at Quarryhill, because they are growing monsoonal climate plants in a Mediterranean climate.

Yes they do water - and the plants are in more of a woodland setting than they are here. I use drip; they overhead water. I think that I am pushing the envelope with these plants even without the pH issue, but with an inhospitable pH, I will never be able to 'make it up' by more water, cooler location in the garden, etc. I will just sadly put them on the list of things that I cannot grow.