Q.Limes not maturing
I have a potted lime tree outside which has given me some lovely limes. However, I’ve noticed that some of the rest of the limes are not fully maturing. Some clusters of limes remain very very small.
Last week I pruned the tree back hoping this would direct more nutrients to the baby limes and I’ve added more soil yesterday where I thought I saw some root exposure. I’ve fertilized with blaupunkt balls. Whatever is the problem?
Typically, when the fruit starts but doesn't grow, it's because there simply aren't enough roots to support all the fruit. You will actually have better results if you remove a few of the tiny limes from each cluster. You might also want to put the lime into a larger pot, so it can develop more roots.
Some other approaches are to pinch out some or the flowers in each cluster. Of course, good culture is always at the top of the list. Here are some articles that might be useful: https://www.gardeningknowhow.com/edible/fruits/citrus/fertilizing-citrus-trees-best-practices-for-citrus-fertilizing.htm
https://www.gardeningknowhow.com/edible/fruits/lime/potted-lime-trees.htm
https://www.gardeningknowhow.com/edible/fruits/lime/tips-for-pruning-lime-tree.htm
