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Colourful hydrangea flowers in the garden
Once considered an old-fashioned plant, gardeners are realising that the hydrangea, with their attractive bold foliage and huge fluffy flower heads, are perfect for the shady garden or in difficult shady areas.

What you need to know about hydrangea

Name: hydrangea (Hydrangea macrophylla cvs).

Plant type: small to large deciduous shrub.

Height: variable, range from 0.5–2m.

Foliage: large (10–20cm long × 10cm wide), oval-shaped but variable, serrated edges, deep to bright green.

Climate: all but arid zones.

Soil: moist, rich, well-drained soil.

Position: part shade or dappled light under trees.

Flowering: November to February. Shades of pinks, blues and white.

Feeding: gross feeder. Requires annual fertilising and mulching with compost or composted manures.

Watering: requires reliable moisture, especially while actively growing and flowering.

Appearance and characteristics of hydrangeas

The hydrangea is dormant across winter and bursts back into life come spring. Most plants will naturally form a dome-shaped shrub, meaning flowers are borne clear of the foliage. A plant that’s performing well can be almost entirely covered in blooms. 

The hydrangea is notorious for changing flower colours. This all relates to soil pH. The simple rule is this: acid for blue, alkaline for pink, and white will always be white. Colour is genetically limited, so a blue will only be able to get to a certain intensity of blue, for example. You may be happy whatever the flower colour, but changing it is reasonably simple:

  • Invest in a simple pH test kit.
  • Test the pH at a couple of points around the plant and average the results.
  • Once pH is known, apply an appropriate product to adjust as desired.
  • Hydrangea “bluing” and “pinking” products are available. These need to be applied regularly from early spring.

Required pH levels for the various colours are as follows:

  • pH 4.5–5.0 = deep blue
  • pH 5.0–6.0 = light blues through mauve
  • pH 6.0–6.5 = solid pink
  • pH 6.6–7.0 = lipstick pink
  • above pH 7 = crimsons

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Uses for hydrangeas

Hydrangea is a bold shrub that adds real “wow” to shady areas. The foliage provides an excellent filler and backdrop for other smaller plants. The hydrangea is unsurpassed for its flowering display in shady spots, and the flowers are excellent for cutting and displaying in a vase. Hydrangea is a great problem solver, as it’s happy in shade and moist spots. 

How to plant and grow hydrangea

Your hydrangea will generally require part shade or dappled light. In some circumstances, some forms will tolerate full shade or even full sun. Soil must be of good quality with good drainage.

Hydrangea is classed as a “gross feeder”, which simply means it is very hungry, so add extra organic matter if required.

Protect your plant from strong winds, as their stems are brittle, and ensure it has reliable moisture, especially during peak growing times.

Planting hydrangeas

Hydrangeas will always do best if soil is improved at planting time with extra composted manure or compost. For best results, add a controlled-release fertiliser.

Caring for hydrangeas

Watering appropriately is critical for best performance. During warm weather and peak growth times, make sure soil remains moist, or both flowering and foliage will suffer. Consider installing a suitable computerised drip irrigation system at planting time to make correct and efficient watering a set-and-forget task.

Maintaining your hydrangeas

Hydrangeas like rich soil with plenty of organic matter and nutrients. This is easy to achieve. Mulch in spring with compost or manure, then add organic mulch over the top. Lucerne or pea straw are excellent, as they break down quickly, adding extra organic matter to the soil. Pruning hydrangeas

Hydrangeas flower on the previous year’s new growth, so pruning is essential for best flowering. Follow these tips for best results:

  • As new shoots develop in spring, remove weak or spindly shoots.
  • After a flower finishes, remove it. Trim it down to where you find a pair of plump buds and cut it off a couple of centimetres above this.
  • Avoid removing stems that have not yet flowered—these are next year’s flowering wood.
  • In late winter, after leaves have fallen, you can conduct more serious renovation pruning, removing any dead and dying wood or older shoots that have become non-productive.

Diseases and pests

Scale insects may occasionally attack hydrangeas. These are easily treated with a suitable horticultural or pest oil. Powdery mildew may appear on leaves as a grey/white powdery dusting. Remove infected leaves, seal in a plastic bag and dispose of them. You can also spray with a suitable safe fungicide such as Eco-Fungicide.

Growing hydrangeas from cuttings

There are a number of easy techniques for growing a hydrangea from cuttings, including:

  • Take 10cm soft-tip cuttings in October/November. Dip in suitable cutting gel, place in a pot of propagating mix, and keep moist in a warm shady spot.
  • Take a stem cutting around 5cm long that has a plump bud, and treat as above.
  • Take 10cm or so of hardened wood in winter and treat as above.

Start planting today

Check out our huge range of plants now and get your garden growing!

 

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Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.