Hydrangeas (Hydrangea sp.) are beautiful, ornamental shrubs known for their large flower heads and lush foliage. Each flower head consists of clusters of small flowers, which vary in bloom, depending on the type. There are many species and cultivated varieties of hydrangeas but not all grow well in our climate.
Lace-cap hydrangeas do not do well in zone 5. Caring for hydrangeas is fairly simple, if you plant hardy varieties. They are generally thought to be rather disease and insect-resistant, although fungus may attack occasionally.
Hydrangeas will grow well in our area, if given the proper care. They need rich soil with lots of organic material in it and prefer slightly acidic soil (this can be easily accomplished by adding either sulphur or peat moss to the soil). They are heavy drinkers that need frequent watering but any standing water will kill their roots so take care not to overwater. Hydrangeas can tolerate deep shade but thrive best in partial shade. They do well with regular fertilization but it should be discontinued by July, in our area, to give them time to harden for the winter.
Some hydrangea flowers will change color, depending on the pH of the soil. Acidic soil will generally produce blue flowers and alkaline will cause the blooms to be pink! Alter the color of your flowers by changing the soil. Add sulphur for more acidity and lime to reduce acidity.
The Endless Summer (Hydrangea macrophylla ‘Endless Summer’) was first developed by a nursery in Minnesota and is hailed for its hardy vigor and lovely flowers that bloom on old and new wood. It grows 3-5 feet high and will bloom in late July. Panicle “PeeGee” hydrangea (Hydrangea paniculata) is another hardy shrub that will grow well in zone 5. It is unusual among hydrangeas in that it can grow to almost ten feet high and produces cone-shaped flowers that bloom slightly green, become white as time goes on and turn pink towards the end of their life. There are several varieties within the “panicle” category, including Pinkywinky and Limelight. The Annabelle hydrangea (Hydrangea arborescens) is one of the showiest varieties, with giant white blooms that can reach 8 inches across!
Hydrangeas function best when pruned lightly, on a yearly basis. If they are not pruned, they will grow too leggy, their stems too tall to hold the weight of the large flower heads. They can also develop a fair amount of old wood, which will not grow flowers at all. Prune a hydrangea in the early spring, making cut at a 45° angle, where the branches converge. Regular dead-heading is also beneficial, to encourage more blooms.
For winter protection, mulch hydrangeas thickly around the base of the shrub. Make sure there are several inches of insulating material, whether it is bark chips, leaves, cardboard or straw. Hardy hydrangeas make a beautiful addition to the garden!
