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Gardening With Hydrangeas

Easy to grow and care for, they’re not troubled by pests or diseases and their blooms dry well.

If I had to choose my favourite flowering shrub, hydrangeas would top the list. Their finest features are their attractive, fragrant, long-blooming flowers that come into bloom in midsummer and continue to do so for weeks. Easy to grow and care for, they’re not troubled by pests or diseases and their blooms dry well.

Their flowers don’t have petals, but instead panicles that consist of colourful sepals that are sterile, which the plant uses to attract pollinating insects. The fertile florets, small and inconspicuous, are found in the centre of the cluster. Because the hydrangea’s sepals cannot be pollinated, they don’t go to seed, and therefore, result in longer-lasting displays.


The smooth hydrangea (H. arborescens) is a North America native that is hardy to Zone 2b. This species thrives in light shade in humus-rich, slightly acidic soil and requires plenty of moisture. Smooth hydrangeas flower on new wood, therefore, should be cut almost to ground level each spring. Its rounded flower heads first appear apple green in colour, then mature to a bright white. Old blooms turn brown, and should then be pruned off when flowering finishes.

The “Annabelle” variety is one of the showiest flowering plants we can grow on the Prairies. Plants grow to three feet in height and do well in sun or shade. Their white globe-shaped flower heads (12 inches wide) develop at the end of each branch and maintain their bright-white colour for up to six weeks starting in mid-to late summer before fading to a straw colour in the fall.

Big leaf hydrangea (H. macrophylla) is the colourful shrub that many gardeners have a passion for. However, most cultivars are not hardy in much of Canada. They bloom on previous season’s growth, which means the stems die back to the ground. There are two main types of big leaf hydrangeas. The flowers of mophead (also known as hortensias) produce big globes of star-shaped petals, while the lacecap types have flattened flower heads with frilly blossoms in the centre and larger florets around the edges. Both types prefer part shade and moist, woodsy soil enriched with leaf mould and peat moss. For best results, keep shrubs well watered throughout the growing season.

“Endless Summer,” a recent variety, is a reblooming hydrangea that finally brings the beauty of H. macrophylla into more Prairie gardens. Hardy to Zone 4, it blooms on both new and old growth, producing big, showy flower mops eight inches across. Flower colours range from pink to blue but can be altered by changing soil acidity. The lower the pH, the deeper the blue. For blue flowers, apply aluminum sulphate. For pink flowers add garden lime or a high-phosphorus fertilizer. Use any amendment according to package directions. Removing the spent flowers will ensure blooms right up until frost. For winter protection, a 10-centimetre-thick layer of winter mulch is recommended.


Hydrangeas can be planted around house foundations or in flower beds. They are also stunning specimens in the lawn, and make a colourful boundary border mixing well with many other shrubs. Smaller cultivars are even suited to large pots.


Plant hydrangeas in spring at the same depth at which they grew in the nursery pot. Keep the soil moist the first growing season and water during dry spells after that. Add a three-inch layer of organic mulch to retain soil moisture. Shape the plant and remove weak or damaged branches 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 fall.

– Patricia Futros writes from Dugald, Manitoba

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