Are the newer leaves coming from the centre of the plant ok? If so I wouldn’t worry ... that could well be due to physical damage or a result of the unusually cold weather.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
What @Dovefromabove said. It's also normal for allium leaves to start looking manky and dying back before the flowers open, so I don't think you have anything to worry about. Have close look at the whole plant pic here - you can see that the foliage is starting to die and if reputable sellers can't get pics of the open flowers before the foliage starts to go over, it's a pretty good indication of what to expect. In this one it looks to me as if they've trimmed brown ends off some of the leaves for the picture.
Doncaster, South Yorkshire. Soil type: sandy, well-drained
Thank you @Dovefromabove and @JennyJ! I was worried it would spread to the other leaves soon. Indeed the weather has not been too warm for this time of the year 😖. Thanks for the advice!
Posts
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.