If there was any fruit that identified most with Southern California, that icon of buttery goodness would be the avocado.

And out there, the king of avocados is the Hass. Once an obscure cultivar, it now accounts for 80 percent of the world’s avocado crop and 90 percent of California’s avocado crop, where San Diego leads the way with the highest number of orchards.

Its namesake, Rudolph Hass, was a US Postal Service carrier and a hobby horticulturist living in La Habra Heights, California. In 1926, Hass purchased seeds from a fellow avocado enthusiast and planted them in his fledgling avocado grove.

The subspecies of the seeds was never known, but many believe they came from a Guatemalan hybrid that had already been cross-pollinated by the time Hass bought them.

Only one seedling survived out of those seeds, and after many failed attempts to graft the seedling with branches from Fuerte avocado trees (the industry standard at the time), Hass decided to leave his little tree be… after being convinced not to cut it down in favor of his more reliable cultivars.

When the tree began bearing odd, bumpy fruit, Hass and his family sold what they couldn’t eat to co-workers at the post office and to the Model Grocery Store in Pasadena. The superior flavor and high demand firmly put the Hass avocado in its place as a luxury fruit, selling for $1 each (equivalent to today’s adjusted cost of $15… can you imagine paying over $30 for a bowl of guacamole these days?!).

Hass patented his tree in 1935 (the first U.S. patent ever granted for a tree) and contracted with a local grower, Harold Brokaw, to produce grafted seedlings from the cuttings of this tree. The Hass avocado grew quicker, yielded more, lasted longer, and tasted better than the Fuerte avocado, eventually becoming the Big Kahuna in the commercial avocado market by the 1970s.

From that single mama tree that Rudolph Hass started from seed, comes every single Hass avocado tree that exists in the world today. Just imagine the first cuttings that Brokaw took, spawning generations of cuttings over the course of 80 years, all propagated from that one tree. How trippy is that?

The mama tree lived on in suburbia after Hass’ death in 1952 and was cared for by Brokaw’s nephew until its own demise in 2002. The tree struggled with root fungus for more than a decade and was eventually cut down. Two plaques commemorate the spot where it grew near a private residence at 426 West Road in La Habra Heights, California (should you find yourself in the neighborhood and want to wow yourself with a piece of agricultural history).

If you live in California and have an avocado tree in your yard, chances are it’s a Hass (though if you have a very mature tree, like I did, it could easily be one of the seven other varieties grown in this state). And chances are, it’s just dripping with fruit right about now, and you’re wondering when they’ll start to soften.

Don’t make my mistake the first year I moved into my house, and just wait… and wait… and wait… until my avocados started dropping to the ground one by one, over-mature. And definitely don’t pick them before their prime, else you’ll just cut into a piece of rubber that even tastes like rubber (yes, I’ve tried).

So how can you tell when an avocado is ripe on the tree? The short answer is, you can’t.

I know, not very helpful. But wait!

The long answer is, avocados do not ripen on trees. This goes for all varieties, but since there are over 900 of them out there (and 8 that specifically grow in California), I’ll focus on the Hass.

Avocados are unique in that they ripen once they’re off the tree. That means that if you’re not ready to harvest them all yet, the best place to store your avocados is on the tree.

The Hass variety is known for being an exceptional keeper, maturing in winter and continuing to develop its flavor through summer. (Californians are incredibly lucky to have avocados year-round because of this, and in great, cheap abundance!)

Hass avocados start as smooth, bright green fruit. As they mature, their skin turns increasingly pebbly and purplish-black. The longer the fruit is left on the tree, the higher the oil content and richer the flavor it will develop. But leave it for too long, and the oil inside the avocado will turn rancid and the fruit will naturally fall from the tree (at which point it’s no longer good).

Harvest typically begins in February and goes as late as September. The tricky part is that even among the Hass cultivar, many factors can affect the maturity rate of the fruit, including climate (was it uncharacteristically warm that year — or cold?), soil (was it under-fertilized or over-fertilized?), and even bearing pattern (low yields and late maturity one year — usually due to cold — may result in high yields and early maturity the next year).

The best way to tell whether your fruit is ready for harvest is to pick one nice, large, dark avocado from your tree, and then leave it out on the counter at room temperature. At this point, the thing is rock hard. You can practically use it as a pestle for your mortar, or even a weapon for self-defense. Have you ever dropped an unripe avocado on your toes? Oy, it’s not pleasant.

If the fruit softens evenly within a week or two, then the rest of your avocados are good for the pickin’. If the fruit turns rubbery or shrivels up, then it isn’t quite ready yet. Keep checking every couple of weeks by picking one fruit at a time until you find an avocado that ripens to the right consistency and flavor of your liking.

You can speed up the ripening process by placing your avocados in a paper bag, which helps them ripen sooner by trapping the natural off-gas that they generate (an active plant hormone called ethylene).

Avocados are climacteric fruits — right up there with apples and bananas — meaning they start to ripen off the tree through a process of ethylene production, which occurs when starch converts to sugar. This stage of climacteric signals the peak of ripeness for an avocado.

If you want to speed it up even more, you can stick an apple or banana inside the bag (or any other ethylene-producing fruit, such as peppers, peaches, tomatoes… whatever you have on hand).

The “gas chamber” created from having all these fruits emitting ethylene together will ensure your avocados ripen in just a few short days. The skin will turn darker (almost black) and become bumpier.

To check for softness, feel the fruit around the base of the stem — there should be a slight give. I also like to wrap my whole hand around the fruit and feel for a uniform suppleness. Avoid feeling up the fruit with your thumb, as the pressure can leave ugly brown spots on the flesh. You can also tell an avocado is ripe if its stem pulls off easily.

A perfectly ripe California avocado is rich and nutty… creamy and velvety… practically melting in your mouth. It’s a pure and simple slice of California gold!