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Plants and their growth patterns entertain and fascinate. You may find this nearly as ‘geeky’ as Sheldon Cooper’s ‘Fun With Flags’ on the hit TV series, “The Big Bang Theory.” Feel free to have a good laugh and then try these methods for seed sprouting yourself!
Once upon a time, the accepted method for sprouting avocado seeds involved a jar of water, three or four wooden toothpicks, and a fresh avocado pit. The method occasionally worked, but I lost my fair share of seeds to rot and forgetfulness. If the seed didn’t rot where it was pierced by the toothpicks, then chances were I’d forget to top off the water and it would dry out.
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One can rarely raise an avocado tree, Persea americana, to actually generate avocado fruits in our climate. The trees, and yes you need at least two to increase the chance that its flowers can be fertilized, must have winter protection. Trees normally don’t flower or produce fruit until they are close to five years old, and may take longer than that.
A few hybrids have been developed that grow in Florida, and can withstand temperatures down to around 20F in winter. But most varieties of avocado don’t respond well to any frost. These subtropical trees will eventually grow to nearly 60′, which makes it a bit challenging to bring them in for our winter months.
Yet the young trees are very attractive, and some homes with large windows and high ceilings can accommodate at least a young tree. Native to Mexico and Central America, Persea americana technically produces berries, not fruits. Each avocado ‘berry’ has a single seed. Flowers are produced in a panicle, like blackberry flowers, and so a whole group of avocados develop together from a central stem.
Commercially, avocado trees are grown from cuttings grafted onto various rootstocks because the hybrid parent won’t produce seeds true to itself. It is still worthwhile to grow an avocado tree from a seed at home, for the fun of it, and to enjoy the tree as a winter houseplant and summer time potted patio plant.
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We ate a lot of avocados in late winter and early spring. What can I say? Avocado on toast, topped with a slice of tomato, sustained us through our cold, wet spring. And those seeds were just too good to throw away. I decided to try out a few different ways to sprout them.
I’ve been starting cuttings, especially broken pieces from our Christmas cactus plants, in wine glasses partially filled with fine aquarium gravel for a while. One day, I decided to plop a particularly fine looking avocado pit into one of those glasses to see what would happen.
When starting an avocado seed partially suspended in water, the idea is to have the water cover only the bottom third to half of the seed. The pointed end of the seed is its top, where a stem will eventually emerge. The rounded end is the bottom, which should be kept wet to stimulate root growth. It made perfect sense to me to simply set the seed on the gravel, partially fill the glass with water, and see whether a root would emerge.
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This root comes out of the very bottom of the seed, directly into the aquarium gravel, and isn’t visible through the glass.
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Avocado pits are clunky things, and the initial root is thick and sturdy. The pit must first crack before the root will emerge from the center of the seed. It’s also from the crack in the seed that a stem will eventually emerge, weeks later, as the new plant begins to grow. Perhaps the long duration of this initial germination is what invites rot when the seed is pierced by toothpicks and then suspended over a jar of water. I changed out the water in the glasses frequently to keep everything fresh.
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While I was waiting for these seeds to germinate (and my counter space was filling with wine glasses) I was inspired to try the same method I’d used earlier for date seeds, to see whether avocado seeds would respond.
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This seed has been wrapped and bagged for more than a month now, and is beginning to show a root. I’ll pot it up in another week or two.
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After cleaning up the seed of any clinging avocado fruit, I simply wrapped up the seed in a damp paper towel, sealed it into a zip lock sandwich bag, and popped it into a cupboard. Yes, into a cupboard. I used a cupboard over the stove, where I knew the seeds would stay warm as they germinated. Check on them as you think about it. Sealed into the bag, the seeds will stay moist enough to begin to germinate without rotting in standing water. After a month or more, you will see a root begin to emerge.
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Once the seed’s root has emerged, pot up the seed in good potting soil, and keep it just damp while waiting for the stem. I potted up a group of seeds and left them in my basement work area until their stems emerged, which is why the stem is pink and not green! Now, I’ll bring it out into the light as it continues to grow.
Please notice that the seed should be planted at the soil surface, not completely buried in the soil. You can get some interesting effects by planting the seed very shallowly, leaving most of the seed visible as the tree begins to grow.
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The one green stem has been growing up in the garage, where it gets some light. I’ll move all of these pots out onto the deck by the weekend. Only partially bury the seed in soil when you initially pot it up.
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If your seeds germinate in spring, you can grow them outside, in a protected location, for their first season. Remember to bring them inside before frost, giving them as much light as you can. If your seeds germinate before outside temperatures remain at least in the 50s, then keep the growing trees indoors until the weather is settled.
Give the tree good potting soil, feed with a time released fertilizer like Osmacote or use a product like Neptune’s Harvest every few weeks during the growing season. Re-pot the trees as their roots fill the pot, or trim the roots and prune the canopy to dwarf the plant.
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This is a great activity to do with any botanically inclined young person in your life. It allows for a close-up examination, in very slow motion, of the germination process and the initial growth of roots and stems.
Allow young people to experiment with the germination process, draw the seed in various stages of growth, photograph the growing plant, and write about their sprouting tree. Home school parents can bring in lots of interesting history, geography, food preparation and math to add depth to the botany.
Or, one can simply start the seeds for the sheer joy of it, and have a bit of fun with avocado plants!
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Nature is messy. Don’t worry so much about always getting it ‘right.’ Have fun and watch the process unfold….
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Woodland Gnome 2019
Forest Garden 