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I have some lovely grapes on my Muscat Hamburg vine. it is in a cold greenhouse and very healthy but I wonder why the grapes have not turned black yet. They are growing under a polycarbonate roof and I  wonder if this is why they are staying green ? They are thin skinned and I tries one or two and they are very sweet.  Will they need sun thro'glass to turn black or am I just wanting to rush them on ? I would be so pleased to get an answer to this.


  • DovefromaboveDovefromabove Posts: 87,935

    I've no experience of greenhouse vines, only outside ones, but this site which I rate very highly, suggests that the Muscat Hamburg can benefit from a little heat in cool autumns.  Although September hasn't realy been cool, it was cool here in August and is cooling down now.  Perhaps  a little heat now would be a good idea.


    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.

  • steephillsteephill Posts: 2,838

    It may not be the variety you think it is, possibly mislabeled. If the grapes are sweet and green that would indicate that it isn't a red grape. Normally it takes about 6 weeks from turning black to get to full ripeness. It might be one of the other muscats, perhaps Muscat of Alexandria.

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