Use an acid fertilizer as instructed by the package.. look for, use on azaleas, blueberries on the label. Make sure it has micronutrients such as manganese, Zinc, Iron, magnesium, etc. I think the ph should go down. Wait to see what others say as I grow kumquats nagami and meiwa from seed. Their need are a little different from other citrus.

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You can see the veins and the yellowing leaves on my meiwa kumquat tree. Despite this, the tree has grown very well and seems quit healthy and happy. Click the link below to see Meiwa 's first birthday pictures

Here is a link that might be useful: http://s1094.photobucket.com/user/wreristhechimney/slideshow/HAPPY%20BIRTHDAY%20TO%20MEIWA%20ONE%20YEAR%20OLD