One of my Clematis is developing yellow leaves from the bottom up - I am thinking it might be magnesium deficiency

does look like trace element deficiency. have you tried your local pharmacy for epsom salts or is the gc closer? but due to the extra heat is it getting enough water? Knowing you it will be but it might just not get its fair share.

I dont think it is viral disease though.

how old are the leaves spritz and is it an evergreen variety? if evergreen then these are the oldest leaves . as they die the chlorophyll is reabsorbed leaving the leaf looking a bit yellow.

Looks like lack of water as the other leaves look fine. As you know, Spritz, it's the new leaves which are the guide. I'd soak it, and mulch it and see how it goes.

It isn't lack of water...I've had the hose on the garden for an hour at a time on each border, moving it round so the whole garden is getting watered. I looked at the plant this morning again, and the yellow-ness is moving up.
It's a decidous Clem. called 'Semu' and I planted it last autumn.

Yes, the GC is closer. Our Pharmacy is in the Doctors' Practice and only dispenses prescribed medication. I'm waiting for my roses to arrive then I was intending to go off to get some plant food from the GC.

Other people's opinions are appreciated. Thank you, both. :-)

I have to give mine Epsom salts Spritz as the leaves go yellow and spotted brown. I get ES from supermarkets as its 1/2 the price of a chemist or GC. I put a good handful around each plant and gently hoe it into the mulch already there I then wait 2-3 days for rain rather than wash it away with watering. If it does not rain I very gently water it in and repeat very 6 weeks till its had 3 doses.
As you have kept it well watered I would just add the Epsom salts and not water for 2 days - its worth trying.

Thanks, Denise - I got some from the GC yesterday...I treated the Clematis as per the instuctions on the box, but I think the salts might have washed away when I watered it. I'll repeat the process in a couple of weeks rather than waiting a month, but I'll be watching the leaves like a hawk, anyway!

I(t works for me so fingers crossed Spritz.

How long might it be before I see any change, Denise?

Mine was much worse than yours Spritz, the first time this happened was I think it was 3 summers ago, I removed the badly affected leaves/stems to the ground and the new growth soon appeared and looked healthy and in six weeks I had quite a bushy healthy plant again. If its mag def I find mine respond in 2-3 weeks providing I have not let it get too bad. So since then every spring I start them off with Epsom salts and do that 3 times each summer.

That's really interesting ladies, thank you! I've had yellowing like this before, but never used Epsom salts....although I'm sure somebody has suggested it in the past! This time, I shall remember the advice! my clems are dreadful this year....either very late, or totally disappeared! Like you, I've been watering a lot!

My 'Royal Velours' has done a vanishing act. :-(((( It was beautiful last year, too.

I get so fed up with that....and then one re-appears and I fall back in love straight away!

perhaps that's a good reason for having so many.....I know at least 'some' of them are going to perform!

I have 14 at present 11 are doing well. The President and Tetrarose have both failed to appear this year, and Pink Fantasy has flowered well but has not reached 18" in height, no idea why some do this?

They fall prey to slugs and earwigs in the spring I think Denise. because they are one of the earliest plants to start in to new growth, they are very vulnerable to hungry pests, and getting rid of the problem is incredibly hard! Grrrr!

That may well be it Karen the slugs in my garden thrive even with the Frogs and Newts which eat them.