Place the cherimoya seed in a small bowl. Cover it with distilled water. Let the seed soak two to three days.
Add seed-starter mix to a pot to within ¼ inch of the rim.
Push the seed ½ inch into the soil. Cover the hole with seed-starter mix. Press lightly with your fingers to firm the surface.
Saturate the seed-starter mix with tap water. Let the excess moisture drain. As the soil surface dries, water the seeds to keep them hydrated.
Place the pot on an electric propagation mat. Set the thermostat to 70 degrees Fahrenheit to facilitate seed germination. Sprouts appear in three weeks.
Transplant a 3-inch-tall cherimoya seedling to an 18-inch pot to accommodate the developing taproot.
Dig a hole 18 to 24 inches deep when the seedling grows 12 to 18 inches tall. Mix the native soil with 1 inch of manure.
Cut the seedling's leaves in half to reduce transpiration while the roots adapt to a new spot.
Take the seedling out of the pot. Trim the taproot tip to promote the development of new lateral roots.
Position the Cherimoya tree in the hole at the same level as it grew in the pot. Refill the hole with the manure-amended soil.
Water the tree to the root zone as soon as it has been transplanted.
Build a 2- to 3-inch-deep mulch ring around the cherimoya tree. Use wood chips, compost or shredded bark, for example, to slow evaporation.