Avocados are delicious and have boomed in popularity in recent years. They can be eaten with breakfasts and in foods like salads.

However, they can be unpredictable when you buy them, as it’s hard to tell how ripe they are.

Avocados don’t ripen on the tree; they need to be picked to ripen, so you usually need to think ahead and nurture one to be soft but not overripe.

According to experts, there isn’t a magical hack which can instantly ripen the fruit, but there are ways to “speed up” the process.

The experts at BBC Good Food said: “Avocados are stimulated into ripening by the hormone ethylene, which is produced naturally by the fruit itself - and, to varying degrees, by all other fruit.

“Avocados (along with apples, bananas and many others) are climacteric fruit, which means they continue to ripen after they’re picked.

“The best way to harness nature’s methods of ripening is to put your avocado in a paper or cloth bag with a banana, which gives off high levels of ethylene.

“Leave it for one to two days (really rock-hard ones will take longer).”

If you put an avocado in a bag on its own, it will ripen in the same way, but it may take a couple of days longer.

Once your fruit is ripe, it will last for around two days on the counter or up to four or five days in the fridge before spoiling.

If you don’t have a banana to hand, you can use an apple but this does give off a little less ethylene than bananas.

If you cut an avocado and realise it is too hard, there are also some ways you can save it, according to the expert.

They explained: “Wrap and keep it. This is the least quick of the fixes, but it might be the simplest.

“Just put the halves back together as neatly as you can, including the pit, and leave the avocado to ripen.

“Don’t worry if the flesh starts to blacken a little on the cut sides - that’s just where it’s oxidised.”

Other ways to use up an unripe avocado include blending it or baking it to soften it slightly.