Not only is the hydrangea one of the most loved flowers in the world, but it’s also reliable and easy to grow in Australia. Used by gardeners far and wide, hydrangeas offer beautiful bouquets of clustered flowers. With their flamboyant flower heads in cool blue, pink or white, they are one of the signature blooms of the summertime garden.
Traditionally a shrub for shady garden beds or side paths, hydrangeas have spread their wings in recent years, with a bunch of new sun-loving varieties appearing on the scene. They’ve also scaled down a bit, making great potted plants for decks and patios.
Here’s how to grow hydrangeas in your own backyard, so you can have these beautiful summer flowers blooming over Christmas.
Hydrangea spring care checklist
- Fertilise hydrangeas in early spring. A dose of controlled-release fertiliser or manure pellets will encourage plenty of blooms.
- Spring is the best time to take hydrangea cuttings to expand your collection.
- Top up mulch in late spring.
How to care for hydrangeas
In a nutshell, this is what you need to know about growing hydrangea.
- Climate: Hydrangeas can thrive in most climates, except arid regions, where they may struggle due to limited moisture.
- Soil: They prefer moist, nutrient-rich soil with good drainage for healthy growth.
- Water: These plants require consistent moisture, especially during their active growth and flowering periods, so regular, reliable watering is crucial to their well-being.
- Aspect: The best location for hydrangeas is in partial shade or dappled light, particularly under trees where they can receive sunlight while protecting them from intense heat.
- Flowering season: Hydrangeas bloom from November to February, displaying a beautiful array of colours including shades of pink, blue, and white.
- Feeding: Hydrangeas are heavy feeders, and it’s essential to provide them with annual fertilisation and mulch with compost or composted manure to ensure they have sufficient nutrients to thrive.
- Height: Its height can vary from 0.5 to 2 metres.
- Leaves: The leaves are large, measuring approximately 10-20cm in length and 10cm in width. They have an oval shape with serrated edges and are coloured in deep to bright green.
How to grow hydrangeas
Step 1
Choose a spot in the garden that has gentle morning sun and well-draining soil.
Step 2
Dig your planting hole twice as wide and to the same depth as your hydrangea’s root ball. After removing the plant from its container, tease the roots gently and cut away any damaged ones. Place the plant in the hole and backfill with soil, making sure it is level with the original potting mix.
Step 3
Water in well to help the soil settle.
Step 4
Keep the soil moist for the first couple of weeks, as the plant becomes established.
How to grow hydrangeas from cuttings
Hydrangeas are easy to grow from cuttings taken in spring or summer. Take tip cuttings about 10 – 15cm long, cutting just below a pair of leaves. Remove the bottom pair of leaves, then cut the remaining leaves in half to reduce water loss. Plant the cuttings into pots filled with propagating mix and place in a shady but bright spot. Don’t let the soil dry out; keep it just damp, not waterlogged.
Caring for hydrangeas
Planting
Hydrangeas can be planted at almost any time of year, except when the ground is frozen in winter. Plant your hydrangeas at the depth they’re at in their pot. Be sure to consult the plant tag’s guidelines to ensure you space the plants correctly.
Some hydrangea varieties, like oakleaf hydrangea, get quite large, while others are bred to be dwarves. When it comes to hydrangea soil, be sure to plant your shrub in a porous, moist soil.
Position
Where do hydrangea grow best in Australia? Mophead varieties of hydrangea grow best in filtered shade, or else a combination of sun in the morning and shade in the afternoon. They won’t thrive in heavy, all-day shade, especially where there is no air movement around their leaves, as this can lead to problems like powdery mildew on the foliage.
Hydrangea quercifolia and H. paniculata both tolerate more sun – avoid positions that are blasted by hot westerly afternoon sun in summer.
If your area is prone to strong winds, consider planting hydrangeas in a sheltered spot or installing a windbreak.
Soil
Hydrangeas thrive in well-draining, organically rich soil, so dig in additional compost and cow manure at planting. They also love moisture, so add some water-retaining crystals to the soil as you backfill. After planting, mulch the soil surface to a depth of about 3-5cm.
Maintenance
Feed hydrangeas in early spring, with a dose of controlled-release fertiliser or manure pellets. This will give them plenty of nutrients to draw on as they form the flowers.
Choose a fertiliser low in nitrogen, as too much of it encourages leaf growth to happen at the expense of your blooms. Phosphorus stimulates flowering, and potassium improves the quality of your flowers. Top up the mulch layer in late spring or early summer, and once the plants are in bloom, feed them with occasional doses of soluble fertiliser formulated for flowers and fruit.
Watering
Hydrangeas are thirsty plants, so properly watering them is crucial; the prefix of the plant’s name, hydra, even indicates so! Even a day or two without water can affect your hydrangeas, so be sure to water them often. If you notice your hydrangea shrub wilting, give it a good watering, and it should perk back up.
Pest control
Nasties are usually minimal for this plant. White-coated hydrangea scale may appear and can be picked off, but if the infestation is severe, treat it with a product such as Eco-oil.
Hydrangea varieties
The best-known varieties are the mophead hydrangeas (Hydrangea macrophylla), deciduous shrubs growing to 1-2 metres in height and bearing large, rounded flower heads. Lacecap hydrangeas are a smaller group (belonging to the same species), which have more flattened flower heads, where the showy coloured petals form a ring around a cluster of tiny flowers in the centre.
Hydrangea paniculata, native to China and Japan, produces large panicles of flowers on a robust shrub that grows to around 4m in height and is more tolerant of sun. New forms include ‘Candlelight’ and Diamond Rouge’, both of which will grow in full sun or part shade.
The oak-leaf hydrangea (Hydrangea quercifolia) is another lovely form native to the USA. It features deeply lobed leaves, which turn fabulous red shades in autumn, and produces creamy white, cone-shaped flowers in summer.
Sun-loving hydrangeas
For sunny areas of the garden, choose Hydrangea paniculata cultivars that are more sun-tolerant. ‘Candlelight’ bears creamy white flowers that turn pink as they age; ‘Diamond Rouge’ produces white flowers in summer, which gradually morph from pink to rich red.
Double hydrangeas
For hydrangea flowers with a twist, seek out some of the double-flowered forms.
The You & Me Series from Plants Management Australia (PMA), features a range of gorgeous double-flowered cultivars, including ‘Desire’, ‘Forever’ and ‘Romance’.
Long-flowering hydrangeas
One of the newest hydrangeas to hit the market is ‘Magical Revolution’, which produces classic mophead-style flowers with a unique feature: they last up to 150 days! Opening in spring, the blooms go through a colour transformation from pastel blue or pink to pinky-red shades and, by autumn, to deep burgundy. They’re also compact growing plants, so they are perfect for pots and small gardens too.
The Endless Summer range of hydrangeas also offers a long flowering season in the garden, since the plants flower on both old and new wood. The plants can be pruned back all over and will bloom again in about 8 – 9 weeks.
Colour-changing hydrangeas
Apart from the white-flowering varieties (which always stay white), hydrangeas – such as Hydrangea macrophylla – are known for their ability to change colour, producing blue flowers in acidic soils (below pH 7) and pink in alkaline soils (above pH 7). You can manipulate the look of your hydrangeas to suit, but you’ll need to add lime (to make the soil alkaline) or aluminium sulphate (to make the soil acidic) to the soil before buds form.
Blue hydrangea vs pink hydrangea
If you’re desperate to change the colour of your plant, bluing or pinking tonics are available for the purpose. However, the best advice is to enjoy the flower colour your soil produces rather than trying to radically alter its pH, which might also harm nearby plants.
Alternatively, consider growing your hydrangea in a pot. That way, you’ll have total control of the soil conditions. The flowers of white hydrangeas are not affected by soil pH.
How to prune hydrangeas yourself
Many gardeners are hesitant to prune hydrangeas because they think it is counterproductive to remove the blooms, but that couldn’t be further from the truth. Pruning your hydrangea blooms will only help your shrub’s growth for next year.
Only trim back the stems that flowered, making the cuts just above a plump pair of buds.
When pruning a hydrangea, it’s best to take off no more than one-third of the plant at any one time. Your objective also determines how you prune it. If you are just trimming tall plants, take the top growth down a little. If you need to do a severe pruning or rejuvenate the plant, you may want to take the branches all the way down to near the ground.
What month do you prune hydrangeas?
Pruning can be done anytime after flowering finishes, typically in late autumn or early winter. But you can leave it until mid-winter if you prefer.
Pruning Pee Gee hydrangea
Pee Gee hydrangea (Hydrangea paniculata, which includes varieties such as ‘Limelight’), as well as smooth hydrangea (Hydrangea arborescens, also called seven bark and best known for the variety ‘Annabelle’), bloom on new wood. Timing for the pruning of these types of hydrangea is not as critical—you can prune in winter or early spring, and they will grow and flower in the same season.
Pruning big leaf hydrangea
Big leaf or mophead hydrangea (Hydrangea macrophylla) and oakleaf hydrangea (Hydrangea quercifolia) both bloom on the previous season’s growth. If you prune these at the wrong time of the year, they either won’t flower or will flower sporadically. They should be pruned soon after flowering in summer, and never too severely—less than one-third of the plant at any one time.
Some newer varieties of big leaf hydrangea, including the popular ‘Endless Summer’, have been bred to bloom on new wood as well as old wood. This makes them better for cold climates because even if the old stems suffer cold damage, new growth will still bloom. This also provides more flexibility in pruning, since you can prune it at any time of the year, and it should still bloom. Even so, pruning right after bloom will maximise flowering.
Frequently asked questions
Hydrangeas grow best in partial shade, with morning sun and afternoon protection. A spot with well-drained, moist soil helps hydrangea plants produce strong foliage and blooms.
Most hydrangeas flower from November to February.
Hydrangeas thrive in both. Large varieties suit garden beds, while compact or dwarf cultivars grow beautifully in pots where soil and moisture are easy to control.
Yes. Hydrangeas are deciduous shrubs that regrow each spring and flower every summer when correctly cared for.
A healthy hydrangea plant can live for decades. Many well-cared-for shrubs continue blooming for 20 years or more.
Avoid pruning mophead and lacecap hydrangeas in late winter or early spring, as you may remove the buds that create that season’s flowers.
