Gardening secrets for growing care-free hydrangeas

Adaptable and long-lived, hydrangeas produce huge heads of papery florets from summer until fall. Excellent for cutting and drying, the flower clusters crown the upright stems, often accompanied by deep green leaves. Keen to grow your own hydrangeas? Here are some proven gardening secrets.

Hydrangea shrubs are available in an array of soothing pastel colours. However, nestled among the hues are three types of hydrangeas that are especially desirable.

• The smooth hydrangea (Hydrangea arborescens) is a North American native that is hardy to Zone 3. It produces immense white, snowball-like flower clusters that can reach up to 30 centimetres (12 inches) in diameter.
• Another care-free native, the oakleaf hydrangea (H. quercifolia) has large conical white flowers that age to purple, with lobed leaves that turn yellow and red in fall. Suited to Zone 5, it can reach 2.5 metres (eight feet) tall and wide and tolerates shade.
• The peegee hydrangea (H. paniculata 'Grandiflora') reaches 4.5 metres (15 feet) tall and spends most of the summer covered in dense clusters of creamy flowers that resemble cotton candy. Peegees prefer partial shade and fertile soil and are hardy to Zone 3.

The most common species of hydrangea is bigleaf hydrangea (H. macrophylla), which reaches about 1.8 metres (roughly six feet) tall. It is hardy to Zone 6, so will grow well in many parts of Canada.

• The flowers of mophead (or hortensia) types produce big globes of star-shaped petals. In contrast, the lacecap types have flatter flowerheads with frilly blossoms in the centre and larger florets around the edges.
• Flower colours range from pink to blue but can be altered by changing the acidity of your soil. Generally, the lower the pH, the deeper the blue. Lower pH means your soil is more acidic. A higher pH means it is alkaline. For reference, tap water has a pH of about 7.0 and is described as having a "neutral" pH.

For blue flowers
Simply apply aluminum sulphate or a commercial "bluing" compound.

For pink flowers
Add a high-phosphorus fertilizer or garden lime. As always, use any amendment according to directions on the package.

The lovely thing about hydrangeas is they're simple to care for and always put on an elegant, colourful show wherever you plant them. To keep hydrangeas thriving:

• Whether it's in a container or a flower bed, always plant hydrangeas in spring or fall at the same depth at which they grew in the nursery pot.
• Keep the soil moist during the first growing season. Thereafter, only water during dry spells.
• Add an eight-centimetre (three-inch) layer of organic mulch to retain soil moisture.
• Shape the plant and remove any damaged or weak branches right after flowering by cutting stems back to a strong set of leaves. Prune old, woody stems to the ground every two to three years in late winter.
• Hydrangeas aren't troubled by pests or diseases and don't even require any winter protection in colder climates.

Hydrangeas can be planted around house foundations or integrated into flower beds. They're also stunning specimens in the lawn and make a colourful boundary border, mixing well with many other shrubs. If you have a deck or patio that could use some livening up, smaller cultivars are suited to life in large pots.