There is something about sprouting and growing seeds from tropical plants like the avocado that appeals to the kid in all of us. These plants typically don't produce fruit - unless you live in a tropical area where you can transplant them outside - but they do produce attractive houseplants.
Wash and dry the avocado pit to remove any fruit pulp. Allow the pit to dry for 24 to 48 hours.
Insert three toothpicks, evenly spaced around the middle of the avocado seed. These will be used to suspend the seed in a glass of water for sprouting.
Fill a glass or jar with water. Mason jars work well as they provide plenty of room for the developing root system.
Suspend the avocado seed, with the blunt end down, over the water so that the bottom of the avocado pit rests in the water and the toothpicks rest on the rim of the jar.
Place the jar in a warm location where it will receive bright, indirect light. Direct sunlight heats the water quickly and may damage young roots. I typically place mine near the kitchen sink under a fluorescent light for easy access when starting the seeds. If you have a window over you sink, this may be the ideal location.
Check the water daily and refill it as necessary to maintain the same level on the seed. Replace water, if it becomes stagnant. Although I have never had an issue with stagnant water when sprouting avocado seeds, others have.
Be patient. Avocado seeds are notoriously slow to germinate. As long as the seed remains firm without shriveling or softening, it will sprout. Within a few weeks, the seed will crack and a large white root will emerge from the bottom of the seed.
Once the root forms, a stem emerges from the top of the seed and leaves develop. This process may take weeks or even months.
Pot the sprouted seed in a mixture of one part potting soil, one part peat moss and one part perlite using care not to damage the root. Position the seed so that the top of the seed is above the soil level.
Move you avocado plant to a sunny location that receives direct sunlight. Growing the plant in low light conditions results in a tall stem with small leaves. These sun-loving plants need adequate sunlight to develop.
Summer you avocado plant outside in a sunny area, but don't forget to bring it inside when nighttime temperatures begin to dip into the 50s in late summer or early fall.
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