Planting hydrangeas in northern climates

Q: I live in Prince George, B.C. and I’ve recently acquired a beautiful hydrangea that needs to be planted.

I have two questions:

1. Can I transplant into a larger container (so I can bring it indoors over the winter) or does it need to go into the ground?

2. Everything that I have read about planting this beauty says that it would like morning sun but not too much. Is that the case?

I really would appreciate any information you have in regards to northern planting of hydrangeas. I really enjoy the magazine.

Thank you.

I am guessing that what you have is a florist’s hydrangea – one of the bright blue, pink and blue or purplish ones that came from the grocery store or a florist – as opposed to one of the hardy white or pinkish-white varieties? In either case, they don’t mind what passes for full sun outside in our northern climates. Some of the nicest ones I’ve seen growing around town in Prince George are in full sun, and even on the south side of a building tucked against the foundation. They do need well-drained soil (i.e. not heavy clay) and appreciate regular watering and fertilizer to promote that lush growth and huge flower heads that are the hallmark of a happy hydrangea.

Wintering, however, is another story. The hardy varieties of Hydrangea arborescens (usually rounded and almost always with white flower heads, including ‘Annabelle’ and ‘White Dome’) and Hydrangea paniculata (pyramidal flower heads, with more of a tendency to be pink, deepening as the season goes on, including ‘Pink Diamond, ‘Tardiva’ and ‘Limelight’) are just fine overwintering planted outside in the ground.

The borderline hardy varieties, including the highly advertised ‘Endless Summer’ and ‘Blushing Bride’, plus the hundreds of not-hardy blue lace-cap varieties that grow with such abandon down the coast (Hydrangea macrophylla varieties) don’t have much of a chance in our northern winters. Trying to overwinter these or any other almost-hardy deciduous shrub inside is a challenge, as they still need a dormant period – they won’t just keep growing all winter.

Some evergreen shrubs, such as florist’s azalea, are happy inside in a relatively high-humidity high-light condition (a south-facing store window is perfect, as the specimen in Kathy’s Quilts on 4th Avenue proves). The house is just too hot and dry – more of a desert than rainforest.

An unheated or barely heated garage, basement or root-cellar (should anyone still have one of those) can work. However, the secret is to keep the dormant plant dark, cool and moist (but not wet) while it’s hibernating. I usually forget about them and let them dry out. Overwatering can cause rot, too much warmth can cause early sprouting before there is enough light to promote spring growth – it can be done, though (I know people who do this with Japanese maples) and it’s certainly worth a try!