Avocado is packed with nutrients and avocado trees make interesting and lush houseplants. A plastic bag is an effective growing medium for avocado seeds. Slow to reach maturity, often requiring 10 years or longer, your indoor avocado may never become an adult tree and bear fruit. But it will grow into an attractive plant that is easy to start.
Prepare Avocado Seeds
Select four avocado seeds that are whole and unblemished. You will probably be using them after harvesting the avocado meat, so be careful when extracting the seeds not to slice or puncture them accidentally.
Clean seeds carefully in warm water.
Allow washed seeds to dry.
Place clean seeds in a sunny windowsill to cure for a couple of days.
Inspect seeds after curing and discard any that have black spots or deep creases.
Prepare your Avocado Bag
Select a bag that is large enough to contain the seeds with at least five inches of area above the seeds for air circulation.
Take a length of paper towel for each seed and saturate it with warm water.
Wrap each seed in a paper towel, covering it completely.
Place wrapped seeds in the bottom of the plastic bag, spaced evenly.
Avoid adding air to the plastic bag. It should not look like a balloon.
Seal the plastic bag.
Place the plastic bag in a sunny location that doesn't receive direct sunlight. In spring or summer, to keep the bag upright and out of the way you can tape it to a windowpane.
Check your Avocado Seeds as They Develop
Monitor the paper towels surrounding the avocado seeds to be sure that they stay moist at all times.
Add water to the paper towels as they become dry, but avoid adding so much that water starts to pool in the bottom of the bag.
Check the air in the bag to be sure that it smells fresh and not moldy. If you detect a stale smell, replace the paper towels, rinse the seeds and place the seeds in a new bag.
Checking the bag once a week should be enough. After four to six weeks you will be able to see roots emerging from the paper towels.
Allow the roots to grow in the humid environment of the bag for two to three weeks. During that time keep the paper towels in the bag and follow the same watering routine.
Planting Avocado Seeds
Pot your avocado seeds once the roots have emerged and had a couple of weeks to grow. Select a 6-inch pot for four seeds.
Fill the pot to within an inch of the rim with potting soil and bury the seeds, root facing downward.
Space seeds evenly around the pot.
Water the seeds and put them firmly in place.
Place the pot in a warm bright location near a window that faces south or west.