Why isn’t my hydrangea blooming?
When do I prune my hydrangea?
How can I get my hydrangea to produce blue flowers?
What type of hydrangea would be good in my garden?
Are hydrangeas good for pollinators?
These and other questions are answered in Halton Master Gardeners Guide to Growing Hydrangeas. Included, is a quick reference table with information about different types of hydrangeas available at most garden centres, as well as answers to some common questions.
General Cultural Information
Location
- generally woodland understory plants, and thrive in moist but well-drained soils amended with organic matter, e.g. humus, leaf mold, compost
- ideally morning sun with some dappled shade in the afternoon (may wilt in full sun even if the soil is moist)
- not drought tolerant until more established and may not thrive in dry, sandy soils
- sheltered from wind, with snow accumulation in winter or mulch to protect flower buds
- avoid plantings against light-coloured south or west-facing wall
Watering
- water well but less often to encourage deeper roots
- drip irrigation or soaker hoses may help keep the soil moist and foliage dry, reducing the potential for leaf spots
- mulch in summer to keep soil moist and cool
Feeding
- prefer a moderate nutrient level in the soil
- too much nitrogen will result in vigorous vegetative growth (stems, leaves) but little or no flowering
- apply 2″ to 3″ of good quality organic mulch (e.g. compost, well-aged manure) keeping the mulch spread over the roots but off the crown of the plant
- stop fertilizing by the end of July at the latest
- macrophylla and H. serrata cultivars flower colour determined by the soil pH of the soil;
- pH below 6 (more acidic) will usually produce blue flowers
- pH above 6 (more alkaline) will produce more pink flowers
Winter Protection (for mopheads and lacecaps)
- protect buds from cold and late spring freezes by covering with 15 cm of mulch (e.g. leaves, straw) after plants have gone dormant in late fall
- remove winter mulch after all threat of late spring frosts has passed
- be aware that mopheads and lacecaps may not be hardy enough for buds to winter over and therefore may not flower (‘Endless Summer’ is a hardier mophead.)
Can I help pollinators by planting hydrangeas?
The answer to this question might surprise you. The clue is in the flowers. Read the full article (linked below) to find out more.
Halton Region Master Gardeners 