Actual size and flowering may vary slightly based on season.
Blue Hibiscus
Blue hibiscus is a fast-growing Australian shrub with big lilac-blue flowers, 4 to 6 inches across. It blooms heaviest in spring and keeps flowering on and off into fall. It stays green all year and grows 4 to 8 feet tall and wide. Plant it as a color accent in a bed, a large pot or a raised planter.
Best for: Color accents near entries and patios, large pots and raised planters, foundation beds and borders, and butterfly gardens.
Plant it where you see it every day, like near an entry or a patio with morning sun and afternoon shade. The lilac-blue flowers are 4 to 6 inches across. It blooms heaviest in spring and on and off into fall.
It grows well in a large container or raised planter with good drainage. The 5 Gallon Staked size is trained up a stake for a small patio tree shape. Trim it lightly after bloom to keep it full.
Butterflies and bees visit the flowers. It fits foundation beds and borders along walls and fences. Plant them 3 to 6 feet apart, center to center, and trim lightly after each flush of bloom.
Too much water and soil that stays wet are the most common ways to lose it, so let the soil dry between soaks. It takes damage around 20 to 25°F, so cover it on the hardest freeze nights. Strong wind can break it up, and it gets open and sparse if never trimmed.
- Hedge or border3-6 ft apart, center to center
- Foundation bed along a wall3-6 ft apart, center to center
Once rooted, give it a deep soak about once a week in the hot months. Water much less in winter, especially December and January. Let the soil dry between waterings, since too much water, most of all in late summer, can kill it.
It grows in full sun, but in the Valley it does best with some shade from the afternoon sun.
Trim it back lightly after a big flush of flowers. This keeps it full and brings on new growth. Left alone, it gets open and sparse near the bottom.
It takes damage around 20 to 25°F, so cover it on the hardest freeze nights and protect young plants. Wait until late February or March to cut off frozen stems. Strong wind can break it up, so a sheltered spot helps.
Drainage test first. Dig the hole and fill it with water. If water is still sitting in the hole a day later, you likely hit caliche, clay or hard soil, so fix the drainage before planting. If it drains very fast, the soil is sandy. Standing water around roots is a common reason new plants fail.
Weed cloth. Cut it away from the planting hole and where the roots will spread. Remove any plastic sheeting completely, since it keeps water and air out of the soil.
Rock or decomposed granite with no soil underneath. Bring in soil close in texture to your native soil, mix it with the soil below, and build up enough depth for roots before planting.
If you can break through. Use a breaker bar, pick, or jackhammer. Dig through the caliche and break out the solid chunks. Backfill with the soil you dug out, with no compost or manure in the hole. Confirm drainage before planting.
If you cannot break through. Dig narrow holes through the hard layer beside the root ball, not under it, and refill them with the same soil, not gravel. If it still will not drain, plant on a low mound of the same soil.
Root ball. Check the outside edges for any roots circling around. Loosen or cut those so they grow outward. Do not break up the center of the root ball.
Depth. The top of the root ball should sit at or just slightly above the surrounding soil level. Planting too deep can lead to rot and kill the plant.
Drip emitters. At planting, put the emitters on the root ball, on different sides of the plant. After about 2 months, move them to the outer edge of the root ball. Over the first year, add emitters farther out toward the edge of the branches as roots grow. Once a plant is rooted, never water only at the trunk.
Is blue hibiscus a real hibiscus?
No. It is Alyogyne huegelii, a shrub from southwestern Australia in the same mallow family. It used to be classed as a hibiscus, and the flowers look like one. The red, pink, yellow and white hibiscus we carry are tropical hibiscus, a different plant.
How big does blue hibiscus get, and how fast?
It grows fast to 4 to 8 feet tall and about as wide. More water in summer means faster growth. Light trims keep it smaller and fuller.
How far apart should I plant blue hibiscus?
Plant them 3 to 6 feet apart, center to center, for a border or foundation bed. The Spacing tab counts plants for your bed.
When does it bloom?
It blooms heaviest in spring and keeps flowering on and off into fall. Flowers are 4 to 6 inches across. Most are lilac-blue, and some plants have purple, pink or white flowers.
How long does each flower last?
About a day or two. Each flower opens, fades and drops, but the plant keeps opening new ones through the season.
How often should I water it?
Once rooted, give it a deep soak about once a week in the hot months. Cut way back in winter, especially December and January. Let the soil dry between waterings, since too much water can kill it.
Does it need full sun or shade?
It grows in full sun, but in the Valley it does better with some afternoon shade. Morning sun and afternoon shade is a good spot, and pots need that shade most.
How cold can blue hibiscus take?
It is freeze sensitive and handles about 20 to 25°F. Cover it on the hardest freeze nights, and protect young plants. The heat of the city helps it through most Valley winters.
When and how should I prune it?
Trim it back lightly after a big flush of flowers. This keeps it full and brings on new growth. Left alone, it gets open and sparse, most of all near the bottom.
Is blue hibiscus short-lived?
It is known as a short-lived shrub. Soggy soil and too much water, most of all in late summer, shorten its life. Good drainage and deep, spaced-out watering help it last.
What soil does it need?
Any soil that drains well. It does best in light, sandy soil. Heavy soil that stays wet is the main risk.
Does it attract butterflies and bees?
Yes. Butterflies and bees visit the flowers, and it fits well in a butterfly garden.
Can I grow blue hibiscus in a pot?
Yes. It does well in a large container or raised planter with good drainage. The staked size is trained as a small patio tree. See the size guide for each size.
Blue Hibiscus for sale in Arizona, delivered to you
Blue hibiscus is a flowering shrub from Australia that looks like a hibiscus but is its own plant. It grows fast and gives big lilac-blue flowers from spring into fall. This page covers size, spacing, watering, pruning, cold and how it compares to tropical hibiscus.
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Blue hibiscus vs tropical hibiscus
Blue hibiscus is Alyogyne huegelii, a shrub from southwestern Australia. It is in the same mallow family and used to be classed as a hibiscus. Tropical hibiscus is a different plant with red, pink, yellow or white flowers.
How big does blue hibiscus get in Phoenix?
It grows fast to 4 to 8 feet tall and about as wide. Summer water speeds it up. Light trims after bloom keep it smaller and fuller.
How often to water blue hibiscus in Arizona
Once rooted, water deeply about once a week in the hot months. Water much less in winter, especially December and January. Let the soil dry between waterings, since soggy soil is the main risk.
When does blue hibiscus bloom?
It blooms heaviest in spring and on and off into fall. Each flower lasts about a day or two, but new ones keep opening. The flowers are 4 to 6 inches across.
When to prune blue hibiscus
Trim it back lightly after a big flush of flowers. This keeps it full and pushes new growth. Left alone, it gets open and sparse near the bottom.
Is blue hibiscus frost hardy in the Valley?
It handles about 20 to 25°F and is freeze sensitive. Cover it on the hardest freeze nights and protect young plants. The heat of the city helps it through most Valley winters.
How far apart to plant blue hibiscus
Plant them 3 to 6 feet apart for a hedge or border. Each plant can spread 4 to 8 feet, so give a single plant that much room. The Spacing tab has the numbers.
Blue hibiscus in pots and patio planters
It grows well in a large container or raised planter with good drainage. The staked size is trained up a stake as a small patio tree. Afternoon shade helps it through summer.
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