Custard apples are a decadent and deliciously sweet sub-tropical fruit. The Australian custard apple is a hybrid of the sugar apple (Annona squamosa) and the cherimoya (Annona cherimola), and is unique to any other custard apples grown around the world. Originally native to South America, this luscious and flavoursome fruit has Australia as its largest commercial producer.
Prepare Seeds for Germination
Soak the custard apple tree seeds in a large bowl of water, ensuring that they are fully submerged. Let the seeds sit for four days, checking occasionally to remove any seeds that are floating on the surface. Use a spoon to collect the seeds still sitting at the bottom of the bowl after the four-day period, and then place them on a clean cloth or paper towel to air dry.
Prepare the Pot
Use a small garden pot that has drainage holes along the bottom and sides. Fill the pot with equal parts of a well-draining soil, such as sandy loam, and peat. Create a 1-inch deep hole in the center of the growing medium and place the seed into the hole, before covering it with a layer of topsoil. Water each seed until the excess moisture begins to drain from the bottom of the pot.
Propagating Custard Apple Tree Seeds
To get custard apple seeds off to a great start, gardeners should keep a few basic care instructions in mind. Custard apple seeds are more likely to thrive in humid and warm environments that mimic their natural habitat. As such, water, light, and temperature levels are all important considerations to make.
Temperature and Lighting Requirements
Custard apple tree seeds grow more rapidly in temperatures between 64 and 77 degrees Fahrenheit, and should not be placed in direct sunlight until they have fully germinated. Seeds that grow in these conditions usually produce seedlings within 21 days. However, germinating custard apple tree seeds in colder climates may take up to two months.
The growing medium should be moist at all times. If the topsoil is dry, use a watering can to apply water directly to the developing root system. It is best to check the pots daily to ensure that the seedlings have a sufficient amount of water and that the soil is at an optimal growing temperature.
Transplant the Saplings
Transplant custard apple tree saplings to a larger pot that contains potting soil when they reach 3 inches in height. Place in a well-lit area out of direct sunlight until the root system is strong enough to transplant the tree to its permanent home, or when there is no longer the threat of frost.
Caring for Custard Apple Trees
Use a balanced fertilizer every three months until the tree begins to bear fruit, and apply nitrogen annually once the tree is mature. Typically dormant during the winter, custard apple trees do not require regular watering. They do, however, need watering twice a month starting in early spring, when they are actively growing. Use a water timer or drip irrigation system to supply custard apple trees with a sufficient amount of water. Overwatering the tree can lead to root rot, while under watering it can cause the leaves to fall and the fruit to burn in direct sunlight.
Custard apple trees are sensitive to frost. Cold climate gardeners can safeguard the tree by covering it or wrapping the trunk with sponge foam and erecting a temporary shelter to protect the branches.