That's so disappointing. No idea what's gone wrong but am sure someone here will suspect the problem and possible solution. I bought 3 Rosso this year and they are still in pots which I hardly ever water. Good luck with your standard.

Is the pot draining properly?

I know what I'd do Meadowland; take it out of the pot and check it out. I was gobsmacked when i took a dahlia out of a pot and found it waterlogged even though there was grit mixed in the compost. The holes were blocked! Obviously my fault.

You can check without turning it out - water it well and if you dont see water coming out the bottom, there's a problem... then you'll have to turn it out.

Its really windy here, but I think what you've got now will be with us tomorrow - its batten down the hatches time, I dread to think what my display of trailing petunias over the edge of the balcony will look like by the time its finished. Destroyed, I should think...shame, they're currently dangling about 3 feet...

What a shame Julia. I'm not sure if you treat a standard the same as other Lavenders,so just wondered if the compost is too rich and wet for it? Usually they prefer dry poor soil. I hardly ever water mine in the border,and never feed it...anyway,I'm no expert,so it's just a thought..I do hope it recovers x

Aww what a shame. Don't give up on it yet, Nature has given it quite a baptism too no doubt, perhaps raise the pot off the ground so that the drainage hole can do a better job? I have lavenders growing in clay which gets very claggy when it rains and rock hard when the sun shines yet they have survived, fingers crossed for yours too.