If you have a lemon tree in your garden, it is not necessary to pick all the fruit as soon as it ripens. Lemons, like other citrus fruit, ripen on the tree and their flavour does not improve after harvesting. Once ripe, lemons cling on the branches for weeks or months, ready to use, until you remove them from the tree. Over time, their flavour begins to deteriorate and eventually they will fall to the ground. When you want to pick a lemon, cut it from the tree with clean gardening shears.
Familiarise yourself with the variety of lemon tree you are attempting to harvest. Check the average shade of yellow and size of that lemon variety. Some varieties of lemon trees produce larger fruits or are a brighter shade of yellow than others.
Lift the lemon in your hand while it is still on the tree; if it feel too light for its size, it may not yet be ripe.
Pick the lemon when the colour is bright yellow with no trace of green. If there are still tinges of green on the lemon, allow it to remain on the tree.
Pick the fruit from the lower branches first; leave the higher-growing fruit for later in the season.
If the skin of the lemon is beginning to wrinkle, it has been left too long on the tree. It is still edible but it will not contain as much juice.