A friend of mine once planted an avocado tree and as the avocados would grow to full size, he would let them sit on the tree, waiting and waiting for them to get soft before harvesting them. But they never did get soft. The lesson: avocados do not ripen on the tree, but only after they have been harvested. This is the reason that they are often still hard at the market, which is not a sign of an inferior fruit but of one that still needs some time to undergo full ripening, a process which is simple to do at home. In fact, unless you are going to be serving the avocado immediately after purchasing, it is better to buy one that is still hard so that you can control the ripening process and therefore the point at which it will be perfect for consumption.

How do you know when avocados are ripe?

Although most avocados you find at the store are hard, some stores carry ripe, ready-to-eat avocadoes for their customers. An avocado is ripe when its skin turns from green to a dark brown-green color and "gives" slightly when it is gently squeezed. You can select the best, ripe and ready-to-eat avocado by looking for one that is slightly soft, without dark sunken spots or cracks. Obviously, these signs apply not only to avocados that are ripe in the store, but to those at home, giving you signs as to when your fruit has reached the perfect time to be eaten.

Be sure not to purchase avocados that rattle when you shake them. This means the pit is pulled away from the flesh and it is overripe.

How to Store Avocadoes After You Bring Them Home

Never refrigerate unripened (hard) avocados because they will not ripen in cold temperatures.

Unripened (hard) avocados are best stored in a cool dark place until they have ripened.

If Your Avocados are Not Ripe, Here's How to Ripen Them

Place unripe avocados in a brown paper bag to ripen. This traps the ethylene gas they produce and helps them to ripen. A firm avocado placed in a paper bag will ripen at room temperature in about three to six days. As the fruit ripens, the skin color will darken.

How to Speed Up the Ripening of Your Avocados

Add a tomato, apple or banana to a paper bag in which you have placed an avocado. This will produce more ethylene gas and speed up the ripening process. It will usually only take one to three days to ripen.

When to refrigerate avocados

Only refrigerate ripe avocados. Avocados will keep for up to 5 days when refrigerated but leaving them too long in the refrigerator will cause them to lose their flavor and begin to turn dark in color. Avoid slicing avocados before refrigerating as they will turn brown after they are cut.

Handle with Care

If you need to store an avocado that has been cut, wrap it tightly with plastic wrap and refrigerate.

Some of the most common varieties include:

Haas: Grown in California, this variety makes up over 75% of the US avocado crop. Their edible yellow-green flesh has the consistency of butter, and a subtle, nutty flavor. They are about the size of a pear and have pebbly brown-black skin when ripe.

Fuerte: These Florida-grown avocados are larger than the Haas variety, having a more defined pear-like shape and smooth, bright green skin. Their flesh is more watery and fibrous, and they contain half the fat and fewer calories than Haas avocados.

Zutano and Bacon: These varieties have similar characteristics to the Fuerte, but they are less commonly available.

Cocktail Avocado: Weighing a modest one to two ounces, these small, pitless avocados are harder to find but well worth the search.