Physoplexis comosa - not flowering

[brianw]

Seeing this plant on Rob Potterton's weekend thread http://www.srgc.net/forum/index.php?topic=8984.15 Reminds me on how badly I grow this, as regards flowers.
A member of our local Chiltern AGS group brought a similar plant in for display last Friday evening's meeting. Not quite as large and a few weeks behind but just covered in flower heads and very silvery blue leaves.
Mine is many years old, quite green with just a hint of silver, and just a few flower heads showing amongst the numerous small leaves. It has sat outside all year on a raised bench (like a plunge bed but no plunge material) for at least 6 or 7 years, with no protection and in currently a 6-7" plastic pot. It is apparently indestructable but just does not flower much. Last year it had 3 flower heads and they were mostly under the leaves. I did feed it a little last year but as that seemed to produce more leaves have not given it anything this year apart from water.
It did flower much better some years ago. What do you suggest?

[brianw]

I apparently clicked too early and should have added.
I water alomst exclusively with rain water. Could this be a low pH problem?

[Tim Ingram]

I have seen this several times recently growing in tufa and invariably the plants were covered in flower buds. I would think it likely that in a pot it needs growing in a much leaner mix.

[brianw]

This plant continues to confuse me. After its indifferent flowering during the early summer it died back almost to nothing. With this somewhat variable summer it has fresh growth and at least 6 flower heads wanting to grow, the largest of whcih is now ~1/2" diameter and increasing; seems it will be in flower again in a months or so time. Weather permitting.

[shelagh]

Brian one of ours is doing exactly the same.

[Gene Mirro]

Nearly every plant I grow flowers better when it gets more sun.  That includes woodland plants.  Is your Physoplexis getting a lot of sun? 

My Physoplexis will also sometimes go dormant in late Summer.  I always try to keep the soil on the dry side while they are dormant.  You should never let it get completely dry.

Here are some that I grew from seed:

[Gene Mirro]

Also, they like lime.  Try top-dressing with fine dolomite lime in Spring, and let it wash in.

[brianw]

Don't know what I have done right this year, or was it last year, but my plant has over ~25 tight flower heads at present. I am surprised to read on Alpine-L that Cliff Booker has his in flower already. Maybe it is in a warmer position than mine, which is in a pot on a bench outside the alpine house. Just the plastic pot itself is a little protected.