Napa Valley is home to some of the most famous vineyards in the world. With the Mediterranean climate and wide range of soils, gardening here is a breeze. The summers are generally hot and dry, with the southern portion of the valley cooled in the evening by the marine layer. Although these are not ideal conditions for the Australian tree fern (Sphaeropteris cooperi), if planted in the appropriate location and watered frequently, the plant can thrive in Napa.
Choose a shady to partly sunny location in which to plant your Australian tree fern. If you live in the southern portion of Napa, choose a partially sunny area. Gardeners in northern Napa should plant the Australian tree fern in the shade. Avoid planting in low spots, as these tend to become frost pockets during Napa Valley winters.
Amend the planting location by mixing a 3-inch layer of compost and a 2-inch layer of coarse sand into the existing soil to a depth of 12 inches.
Dig a hole that is the same depth and three times as wide as the pot in which the Australian tree fern is growing.
Remove the Australian tree fern from the pot and place the roots into the hole. Backfill with soil and tamp lightly around the base of the plant with your feet.
Water the tree fern until the water puddles. When it drains, spread a 3-inch layer of compost around the base of the tree, keeping it 2 inches away from the trunk. Mulch will help protect the roots of the Australian fern tree in July and August when the weather heats up in Napa.