Once the fruit is mature, it can be left on the tree for a few weeks, but it does not ripen more. So first off, the lemons may not be turning yellow because they have not been ripening on the tree long enough. In fact, the most common cause for citrus fruit in general to fail to ripen is lack of sunlight.Click to see full answer. Also to know is, how do you get lemons to turn yellow?Once the baby fruit is ‘set’ after pollination occurs, the lemon will develop and grow over the warmer months. As each lemon fills out, you will notice the colour start changing from fully green to yellow tinges and finally, full yellow for most varieties. In warmer climates, they may never turn 100% yellow when ripe.Beside above, why are my baby lemons turning yellow? Baby lemons turning yellow and dropping. This is normal and is known as post bloom fruit drop. It is a self-thinning mechanism that adjusts the number of fruit to the tree’s bearing potential. Fruitlets that are defective are also shed at this time. Regarding this, what month do lemons ripen? Lemons ripen anywhere between four and 12 months after flowering. Flowers most commonly appear in spring, the fruit develops over summer, and then slowly turns from green to yellow in fall or winter.Are lemons green or yellow?Lemons are usually bright yellow, while limes are typically a bright shade of green. However, certain types of limes will turn yellow as they ripen, making the distinction a little more difficult.