My grapes are a tad too sour to eat

[jocdave]

Hi I live on mid north coast of NSW just south of Port Macquarie.  I have been trying to grow a grape vine for years and this year it has decided to put on a show with multiple bunches of grapes.  I am not sure of the type of grape only that they are purple/black and a table grape.  Last year we had a couple  of little bunches but either they didn't ripen completely or the birds got to them and the ones we tasted were a tad too sour to eat.

Can  anyone help me out here with some advice on how I can make them sweeter and more edible.

Thanks everyone.

[MitchellMc · Accepted solution]

Hi @jocdave,

The first thing to understand is that the sweetness of the grapes depends on the cultivar planted and growing conditions. The variety that you have might only produce a tart grape. If these are sweet table grapes, the likely answer is that they are not yet ripe. The acid is very high in unripe grapes; as the grapes ripen, the acid goes down while the sugar increases. How much sun does the vine get? The sugars are produced through the photosynthesis process, and if the vine is not receiving enough sun, it can't produce the high levels of sugar needed. Eight hours of sun a day would be a sufficient amount.

Depending on the amount of fruit the vine has set, it might have trouble producing enough sugars to sweeten them all. That doesn't sound like the case here unless you have an overabundance of fruit on the vine. 

I'd suggest you invest in some bird netting and cover the vine. That way, you can leave the grapes to ripen on the vine for as long as possible to ensure those sugar levels are increased. Another thing to remember is that, unlike bananas, grapes do not ripen off the vine. So, once you pick them, they will never sweeten and would be best used in a sugared dessert.

Please let me know if you have any questions.

Mitchell

[jocdave]

Thank you again Mitch, you have all the answers.