Meyer lemon tree pruning
A meyer lemon is not really a lemon... more like a cross between an orange and a lemon. Regardless, they are great lemons to grow and eat. They are also a cold-hardy citrus, far more cold tolerant than true lemons. I grew meyers in California when I lived there, and I love to eat them. You cannot really go wrong with any type of pruning on a lemon tree. In southern California groves they prune lemons right down to stumps and large branches. This is because they want strong branches to hold the fruit up and control the size of the trees (Eureka lemons can get rather large if you let them go). The way that you prune your meyer depends on what you want; a nice hedge or a fruit-producing tree. Or both...
(Note: I am assuming that you have an older meyer lemon tree here.)
Meyers will usually set and ripen the most fruit in winter. So wait until most of the lemons have ripened before you prune your meyer. Then when you are ready to prune your tree, pick all (or most) the remaining ripe fruit off. Then prune any dead, damaged or diseased stems right to the base. Then start the longer task of pruning back the long wispy stems. Weak stems do not hold fruit well. Cut any that are smaller than a pencil. One that is done, cut any remaining smaller/medium size stems that are intercrossing the plant. You want to open the plant up to improve air flow, reduce disease, and make it easier to pick future setting fruit.
Now when that is done, step back from the plant and look at the balance and shape. Is it the shape that you want it? If it is too high, cut all the branches and stems that are above the height that you want it. Remember that it will grow a lot on the top, so cut it shorter than you want it to be. If the plant is growing all to one side, remove stems and branches to balance it out. If you want a more open look, remove more branches and stems growing in the middle of the plant and clear the lower few feet of branches of side stems. If you want a more compact tree from a larger open one, cut the stems and branches back pretty hard. You can also prune to shape it round or square or oval or whatever. You can even use hedge trimmers to do that.
Enjoy your tree/trees and meyers! Send me some if you have extra.