So, how do you know when a lemon is ripe? Well, the color is a big giveaway - a ripe lemon will be a vibrant yellow color, while an unripe one will be more green. But that's not all - the texture and weight of the lemon can also give you clues.
A ripe lemon will be heavy for its size and have a slightly soft texture, while an unripe one will be lighter and more firm. And if you gently squeeze the lemon, a ripe one will yield to pressure, while an unripe one will feel hard.
But here's the thing - even if a lemon doesn't look perfectly yellow, it can still be ripe - some varieties of lemons, like the Ponderosa lemon, have a more greenish tint even when they're fully ripe.
When To Harvest Lemons In Texas at Lynda Rahman blog