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How and when do you prune them?I find that growing the plant/s in a 'goblet' shape "U" allows air around the plant/s.(It also makes harvesting easier too)With due respect, looking at the base of your plants, there seems to be an issue with a proliferation of grass.That along with the relatively dry season we have this year may be a reason for your poor crop.For example, this year my crop is terrific, but sadly the berries are only about half the size they would be in a wetter year. This is how I cultivate my one and only plant/bush; https://www.thegardenersalmanac.co.uk/Content/G/Gooseberry/Gooseberry.htm
Thanks by muck what exactly do you mean? Well rotted manure?