The macadamia tree grows to 40 feet in height with a spreading crown. The hard nut is produced within a green husk, which is removed before planting the seed. Macadamia trees are native to Australia and grow surprisingly well in certain temperate zones, although the tree officially is hardy to U.S. Department of Agriculture Plant Hardiness Zones 9b. If you grow the tree from seed, you'll have to wait four or five years to taste the first homegrown macadamia nut.
Plant a seed freshly fallen from the tree immediately. Otherwise, soak the macadamia seed for 48 hours in a bowl of room-temperature water.
Choose a 12-inch-deep germinating container for the macadamia tree seed. This depth allows the seed to develop a strong, straight taproot.
Fill the container with a combination of moist peat moss and moist vermiculite. Plant the seed 1/4 of an inch deep on its side with the ventral suture (the seam on the seed) facing you – not facing up or down.
Place the heat mat in a sunny area where the air temperature remains between 65 and 85 degrees Fahrenheit. Set the thermostat to 75 degrees and place the container on top. Keep the germinating medium slightly moist at all times. Germination may be slow – the seed typically sprouts after three and six weeks, but may take as long as six months after planting.
Transplant the macadamia tree seedling when it reaches 6 inches in height. Choose a site with full sun exposure all day and deep soil to accommodate the taproot.
Dig up the soil in the planting area to a depth of 3 feet. Loosen it well to provide a deep, loose environment for the trees roots. Do not add fertilizer or organic amendments to the soil when planting.
Plant the macadamia seedling at the same depth as it has been growing. Pack the soil around the roots and water to a depth of 12 inches.
Keep the soil consistently moist until you notice new growth on the macadamia tree. If there is no rain, provide the tree with 1 inch of water a week.
Fertilize the macadamia tree after it has been in the ground for one year. In spring, apply an 8-10-5 formula, at the rate of 18 ounces, or 2 1/4 cups, for each year of the tree's age. Never exceed 11 pounds of fertilizer per season on older trees.
Treat the macadamia for a zinc deficiency if the leaves are small and yellow, or if shoot growth is slow. Apply a zinc foliar spray in early spring, just after the tree begins growing. Apply the spray according to label instructions for the age of your tree.