After some experimentation, we found that the sphagnum bag method was easier and more reliable than the more common practice of puncturing the avocado seed and suspending it in a glass of water. (See The Secret of the Sphagnum Bag, page 8.) Germination time varies with each pit, but the average time is a few weeks.
When the roots are 3 to 4 inches long, transfer the avocado to a pot 1 inch larger than the pit. Fill the pot one-third full with potting soil. Gently place the pit on the soil and fill in enough soil around it so that half the pit is exposed at the top. Place the pot in a warm, bright spot (avocados do not require direct sunlight). Once established, avocados grow quite rampantly. Keep the soil moist, but not soggy, at all times. During their natural resting period from October to January, avocados need less water. As soon as the days lengthen, new leaves will appear and you should give them more water.
Fill a quart-sized, sealable plastic bag with barely moist, long-grained sphagnum moss. The moss should have the consistency of a good unbaked pie crust and should not drip when squeezed. (Long-grained moss is available at most garden centers; if you can’t find any, use regular peat moss.) Place the seed in the bag, making sure it is completely surrounded with the moss. Seal the bag and place it in a warm, dark spot. Check the bag several times a week to make sure there are no soft spots on the tuber or root, or mold on the seed. If it is too dry, add water; if it is too wet, leave the bag open for a day. Seeds or tubers raised in the sphagnum bag will have to be hardened off.
Natty Zickuhr wrote:Any reliable info on sprouting avocados would be helpful. I have tried many times and followed the instructions of several websites (basic gist - toothpick pit, lower half submerged, put in warm sunny place)...never any results. All I grow is algae. I've tried peeling the pits, different water depths, adding liquid fertilizer, and burying them in a potting medium. No roots. What am I doing wrong? Is there a minimum germination temp?