Grow and Care for Banksia

Grow Banksia in full sun, in soil that drains, and skip phosphorus fertilizer. Coast Banksia is Banksia integrifolia, an Australian coastal tree.

Give it full sun, soil that drains, and skip phosphorus

Banksia wants sun and a hole that drains. Water a new tree through the first dry season so the roots take, then skip extra water; an established tree takes dry weather better than a wet hole. [1] Skip phosphorus fertilizer. The roots gather nutrients from lean ground, and a bloom-booster or lawn feed can yellow new leaves and kill those roots. [2] Coast Banksia takes coastal salt spray once it is set. It is a tree, not a dwarf border shrub.

1. Choose full sun. A south or west slope that drains is better than a dark, wet corner.
2. Set it in soil that drains. Sand or lean loam is fine if water does not stand around the roots. If clay stays wet after rain, plant on a raised bed.
3. Water through the first dry season. After that, skip extra water unless the tree wilts in a long drought.
4. Skip phosphorus. If leaves pale on draining ground, use a native-plant fertilizer labeled very low phosphorus — or water only and wait.

Plant a young tree where the soil drains, and leave it room

Buy a young tree in a pot and set the root ball at the same depth it was already growing. Dig a wide hole and put the native soil back in. Do not mix manure or phosphorus fertilizer into the backfill. Leave room for a 30- to 60-foot tree, and keep grass and a deep mulch ring off the trunk. [3]

1. Plant in spring, or in fall where winters stay mild, while you can still water.
2. Dig a hole twice as wide as the root ball and no deeper. Loosen the sides. Fill with the soil you dug out. Do not add manure, composted manure, or phosphorus fertilizer to the hole.
3. Set the top of the root ball even with the surrounding soil. Keep mulch off the stem.
4. Water to settle the soil. Keep the first dry season from baking the new roots. Do not plant into a low spot that stays wet.
5. Leave 15 to 30 feet of width, and more if you want a windbreak. This is a tree, not a patio shrub.

Prune after the spikes fade, and leave green leaves on the stems

You do not have to prune Banksia every year. After the flower spikes fade, you can tip-prune a young tree so it branches, or snap off spent heads. Cut to a leafy side shoot. Do not cut into bare wood; new growth may not come from a leafless stub on a young tree.

1. Wait until the pale yellow spikes fade. That is often late winter into spring after a fall or winter bloom.
2. Tip-prune long shoots on a young tree so it branches instead of becoming a single lanky stem.
3. Take out a dead or broken stem any time.
4. Do not renovate a bare trunk by cutting a young tree to a stump. Replace a plant that has no green wood left to cut to.

Not a bottlebrush — and not a honeysuckle vine

Bottlebrush on a Callistemon tag is a shrub with soft red or cream bottlebrush spikes — see How to Grow Bottlebrush. Coast Banksia is Banksia integrifolia, an Australian tree with pale yellow spikes and woody fruit that stays on the plant.

Honeysuckle in a U.S. search often means Lonicera, a vine or shrub with tubular flowers — see How to Grow Honeysuckle. Grevillea has similar flower clusters, but its fruit is not the hard woody follicle Banksia keeps — see How to Grow Grevillea. Protea is a different genus — see How to Grow Protea. Hakea is a woody cousin — see How to Grow Hakea. Honeysuckle oak on a tag is not a true oak — see How to Grow Oak if the Latin says Quercus. If the tag says Banksia integrifolia, you still have Banksia.

Start from a nursery plant, or sow seed

Most U.S. gardeners start from a nursery plant. If you want a seedling, sow seed from a woody follicle after the fruit splits. Sow in a mix that drains, in its own small pot, so you do not tear the roots later. [4] Cuttings are slow and often do not root.

1. Buy a young nursery plant when you can. That is the reliable start.
2. If you sow, wait until the woody fruit turns dark and hard, then heat the cone in an oven at about 250°F (120°C) for about an hour until the follicles open, and take the two winged seeds.
3. Cover the seed with about its own depth of a gritty mix. Keep the mix moist, not soggy, until it germinates. That can take two to eight weeks.
4. Grow the seedling in its own pot. Do not knock it out until you are ready to plant it in draining ground.

Set Banksia in full sun, in soil that drains, and skip phosphorus fertilizer once the roots take.