Growing Hydrangeas Successfully

The following advice reflects ideal conditions. You can grow hydrangeas with good results in less-than-ideal conditions but there will be some trade-offs. The information below is excerpted from Heavenly Hydrangeas: A Practical Guide for the Home Gardener by Joan Harrison.
 

Macrophyllas (mopheads and lacecaps)
‘Nikko Blue’, ‘Endless Summer™’

  • Morning sun and afternoon shade
  • Rich soil with good drainage
  • Fertilize in the spring
  • Water regularly (soaker hoses are ideal)
  • Mulch to retain moisture and control weeds
     

Paniculatas (panicle)
‘Limelight’, ‘Quick Fire™’

  • Plant in full sun
  • Protect from severe winds
     

Arborescens
‘Annabelle’, ‘Invincibelle™ Spirit’

  • Light shade (can be planted in full sun in the north)
  • Consistent moisture
     

Quercifolias (oakleaf)
‘Ruby Slippers’, ‘Snowflake’

  • Adaptable to both sunny and shady conditions
  • They flower best with lots of heat (natives of southeastern U. S.)
  • Wind sensitive; plant in sheltered site
     

Anomalas Climbing hydrangeas

  • Prefer partial shade but can be planted in full sun
  • Good drainage required
  • Tolerant of poor soil
     

General growing advice

  • Keep the mature size of the hydrangea in mind when choosing where to plant it.
  • Late spring and early fall are good times to plant.
  • Avoid planting on very hot days or very windy days.
  • Before digging the hole, water the plant in its container.
  • Water it in well after planting.
     

Hydrangea paniculata 'Limelight' Joan Harrison
Hydrangea paniculata 'Limelight'
Joan Harrison

Hydrangea paniculata 'Pinky Winky' Janet Schultz
Hydrangea paniculata 'Pinky Winky'
Janet Schultz

Hydrangea macrophylla 'Blue Danube' Joan Harrison
Hydrangea macrophylla 'Blue Danube'
Joan Harrison

Hydrangea arborsecens 'Incrediball®' Joan Harrison
Hydrangea arborescens 'Incrediball®'
Joan Harrison

Hydrangea macrophylla 'Fasan' Joan Harrison
Hydrangea macrophylla 'Fasan'
Joan Harrison

Hydrangea macrophylla 'Purple Majesty' Joan Harrison
Hydrangea macrophylla 'Purple Majesty'
Joan Harrison

Hydrangea macrophylla 'Twist n Shout' Joan Harrison
Hydrangea macrophylla 'Twist n Shout'
Joan Harrison

Hydrangea macrophylla 'Decatur Blue' Joan Harrison
Hydrangea macrophylla 'Decatur Blue'
Joan Harrison

PRUNING

Hydrangea Pruning - Mal Condon, Vice-President, The Cape Cod Hydrangea Society & Curator-Hydrangea Collection, Heritage Museums & Gardens

To prune hydrangeas effectively it’s important to know the plant’s species - macrophylla, serrata, arborescens, paniculata, quercifolia (the oakleafs), and anomala (the climbers). The reason species is so important to pruning is to know whether the plant flowers on new or old wood. ‘New’ wood is growth of the current season with flowers developing immediately from new growth. Arborescens and paniculatas produce blooms entirely on new wood. ‘Old’ wood is growth from the previous growing season; flowers form in early summer from buds developed the previous autumn. Importantly, these buds must survive the winter before developing into flowers during the following late spring. Macrophyllas, serratas, quercifolias, and the anomalas all flower on old wood.

The new wood arborescens and paniculata species are truly ‘bulletproof’ - extremely cold hardy (zone 4) and reliable annual bloomers. Best pruning time is late fall - November through early December - in our zones 6 & 7.

The old wood quercifolias and anomalas require relatively little pruning. They are both hardy to zone 5 and are best treated as ‘free growers’ left largely to their own growth development. Pruning is a containment exercise - keeping them within ‘bounds’ and removing occasional winter-kill tip sections. Pruning Quercifolias can be left to last - late April - as they are the last species to break bud. For petiolaris, its best to prune after flowering in late June, simply removing spent blooms and errant stems.

Macrophyllas and serratas species have similar flowers with their distinctive lacecap and mophead bloom forms. Mopheads are identified by their full, roundish heads of large petals; lacecaps have tiny fertile flowers in the centre of the bloom with an outer border of larger sterile petals. Both species respond to the same pruning timing and techniques. Macrophyllas are the most popular hydrangea, but they are the least cold-hardy of the species and often require some supplementary winter protection to insure bud survival over a long cold winter. The serratas, though typically more delicate in physical stature, are more cold hardy.

Dead or ‘sun-burned’ blooms can be removed just after flowering. This actually encourages successive blooming on selected varieties that possess this repeat blooming characteristic. The primary pruning time is April; spent blooms and winter-killed tip stem sections can be cut back to the first strong, healthy pair of buds lower down the stem. Aging wood, with exfoliating (peeling) bark, should be removed to encourage the production of new and more floriferous replacement growth. These stems can be cut back cleanly to the ground in late winter when it’s easier to get inside the plant’s base. For newly established plants - 3 gallon and under container size - only minor pruning is necessary for the first year or two. Late spring frosts can be particularly damaging as the tender unfurling leaves of new bud growth is especially susceptible. Prune back damaged stems to just above the first live pair of buds on healthy wood.