Why Our Avocado Plant is Unlikely to Ever Yield Fruit
By: Sam Westreich
Tags: Environment, Food, Gardening, Science, Biology

As a child, I remember carefully inserting toothpicks into the pit of an avocado so that we could balance it over the top of a glass of water, the liquid just tickling the bottom half of the large brown seed.

It always seemed so crazy that a bit of the food we ate (on the semi-rare occasions when we purchased avocados — those were expensive!) could just start growing, from nothing more than being left alone in a cup of water.

Strangely enough, I never remember what happened to all those sprouted avocados. Did we just throw them out? Did they die? Are they still sitting in pots, somewhere, waiting for me to eventually return to my childhood home and rediscover them?

The memories came up more recently, when my wife returned from a friend’s house bearing a new avocado seed — and sure enough, there were the three toothpicks, the glass of water, all just the same as when I was a child.

This time, we didn’t lose the avocado seed at some point. It sat on our kitchen counter for months, and we’d watch as roots extended down into the glass and a little leaf emerged to orient towards the afternoon sun streaming in through the window.

We carefully followed the instructions that we found online; once the shoot had its second leaf, we chopped it off. It felt almost like murder, at the time, but the plant regrew, sprouting a second shoot that put out more leaves.

After another few weeks, it was time for the seedling to be planted in something with more nutrients, space, and holding power than the jam jar over which it had been balanced until now. We transferred it to a pot, which now sits on our back stoop.

An avocado tree, currently about two years old. Note the little knob at the base, where the original stalk was cut in order for the second one to grow.

Now, the plant’s been growing a few years. Looking at it one afternoon, I started wondering: are we going to eventually get some avocado fruit from this tree? Will it eventually flower? Or is it going to be forever ornamental, like a dog too friendly to guard?

I did a bit of reading — and it turns out that, sadly, our avocado tree isn’t likely to yield much.

Here’s the science of why we can’t just buy one avocado from the store, grow it into a plant, and get infinite avocados (#hacked).

These Avocados Are Liars, Seed Speaking!

In gardening, there’s a concept called “true to seed.” In general terms, a plant is “true to seed” if growing its seeds yields another plant with the same characteristics.

Some fruiting trees, like peaches, apricots, almonds, and most citrus trees, are generally true to seed. Plant the seeds from a citrus tree, and you’ll get another tree that produces very similar citrus.

But other fruiting trees, like apples — and avocados — are not true to seed. Instead, these plants are hybrids, and are carefully selected crosses. There’s no guarantee that their offspring will produce similar fruit.

Both of these animals are dogs, but they’re different breeds. Cross them, and you’d end up with a mix (or an angry pooch, which is far worse). Photo by Alvan Nee.

A great way to think of growing “true to seed” is to consider dogs. There are many different breeds of dog, which have very different characteristics — consider a dachshund versus a husky, for example, or a corgi versus a terrier as pictured to the left.

If you breed a corgi with a husky, you’re going to get puppies, because they’re both dogs and can interbreed — but those won’t be corgi nor husky puppies. Instead, the puppies will be a mix of the two breeds, with some characteristics from each parent.