Want to grow an avocado tree from seed? Here's how

When I was growing up, it wasn’t uncommon for there to be a pit of some sort partially submerged in a glass of water, suspended by toothpicks, on a windowsill. Peaches, mangos, avocados – I tried them all.

As an adult, I view the project as a way to create free plants rather than as a science experiment, but it’s still fun to watch the roots grow through a clear glass.

There are several types of avocados. Any can be grown outdoors in horticultural zones 9-11, but the Hass variety, which is smaller and more tolerant of indoor conditions, makes the best houseplant.

Step by step

To make your own avocado plant, follow these steps:

1. Rinse the seed, or pit, from an avocado, then hold it vertically with the pointy end facing up.

2. Insert four wooden toothpicks around the center of the seed to create crutches for it to rest on the rim of a glass or glass jar. Place the toothpick-adorned pit on the glass and fill it with water to toothpick level, submerging its bottom half. Set the glass on a windowsill or under a bright light source.

3. Change the water every couple of days. Within a few weeks, you’ll see roots sprouting from the bottom of the seed, and shoots emerging from the top. Over time, the seed may split and its outer layer will crumble away; this is normal.

4. When the shoots are a few inches tall and have produced leaves, remove the toothpicks and plant the seed, shoot-side up, in light, well-draining potting mix, leaving the tip of the seed exposed. Use a container with a drainage hole at the bottom.

Caring for the plant

As more leaves emerge, prune the shoots back, cutting just above a lower leaf to encourage fuller, bushier growth.

If you are keeping the plant indoors, place it to the side of your sunniest window to provide bright-but-indirect light.

Water the plant only when the soil is completely dry, but don’t let it remain dry for long. To gauge whether it’s time to water, plunge your finger knuckle-deep into the pot to feel the moisture level at root depth. When it’s dry, place the pot in the sink and, with the faucet on low, slowly water the plant until water emerges from the drainage hole.

Fertilize the plant every four to six months with either a product formulated specifically for citrus, mango and avocado plants, or with a slow-release, balanced fertilizer with a ratio of 4-6-4, 5-5-5 or similar listed on the package.

How to grow your avocado plant outdoors

If you’d like to grow your tree outdoors (zones 9-11 only), you should know that avocados are heterozygous plants, which means their seeds will not produce trees or fruits identical to those of their parents. In fact, they could be wildly different.

That’s why most avocado trees have been either grafted or cloned. So, although planting an avocado tree started from seed at home may result in a beautiful specimen, if you want a traditional tree and edible fruit, you’re better off buying a tree from a nursery.

But if you’re the gambling type and would still like to grow your tree in the garden, care for it indoors until spring, then acclimate it to the outdoors by setting it in a shady spot for an hour, then bringing it back indoors. Set it out for two hours the next day, and repeat each day for a week, increasing outdoor exposure by an hour each day.

After a week, plant the tree outdoors. Choose a spot that receives full to part sun and offers protection from wind. The soil should be well-draining and have a pH reading between 5.0 and 7.0.

Dig a hole that is twice as wide as the plant’s roots but exactly as deep as the pot it was growing in.

Keep the soil moist but not soggy, and fertilize every three months with the products recommended above.

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Jessica Damiano writes weekly gardening columns for the AP and publishes the award-winning Weekly Dirt Newsletter. You can sign up here for weekly gardening tips and advice.

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