Lychnis 'Vesuvius'

I have Lychnis molten lava which I planted last year. I find the leaves are yellowish and only had 3 flowers the whole plant seems very slow. Do you find this?

well this has flowered in its first year. the plant is 'thin' and looking at the photo I can see it is in need of a really good drink. Watering can job tonight. Its too hot and windy at the moment. Some of them have a much darker foliage and others are more typical of the maltese cross form.

thanks