Hydrangeas

By Jan Cashman • Posted on July, 15th 2017

The showy shrub around town blooming now full of huge, round, white flowers is hyrangea. Most of the hydrangeas around here have white flowers but plant breeders have been working on new hydrangea varieties that are hardy with bigger, more colorful blossoms and a longer bloom time. Since the year 2000, 90 new hydrangeas have been patented. Endless Summer was the first hydrangea to start this trend of new varieties– introduced in 2004 as a hardy, reblooming hydrangea with pink or blue flowers. Since then, even better varieties have been introduced.

There are four common species of hydrangeas, Smooth (arborescens), Mophead (macrophylla), PG (paniculata) and Oak Leaf (quercifolia). Oak Leaf varieties are Zone 5 as are most Mopheads so these varieties are of questionable hardiness here. Some of the new PG types are listed as Zone 3 or 4 so are hardy for northern climates. Many of the Smooth types, old stand-bys and new introductions, are Zone 3 and will survive our winters.

To me, the best hydrangea for our area is the old stand-by called Annabelle (Hydrangea arboresens). White-blossomed Annabelles tolerate our alkaline soils. Annabelle needs some shade, although those planted on the west side of Aarons Furniture on N. 7th Avenue, a warm sunny spot, are beautiful.

Quick Fire (see chart) is a newer PG-type hydrangea that our customers are liking. Quickfire is one of the first hydranges to bloom in the summer. And it has colorful leaves in the fall. Or try Limelight Hydrangea, a vigorous Zone 3 with large lime-green flowers.

Culture:

The best spot for a hydrangea would be one that gets morning sun only. However, our Annabelle hydrangea is thriving in almost total shade. Hydrangeas prefer acid soils, so use a soil acidifier and a fertilizer for acid-loving plants to lower the soil pH. Here is how my husband’s brother, a nurseryman who lives in Bismarck, North Dakota, planted his hydrangeas: He dug an extra large hole–at least 18″ wide and deep. He discarded the soil and mixed 1/2 peat moss, 1/2 good topsoil and added a soil acidifier.

Pruning:

Hydrangeas that ‘bloom on new wood’ can be pruned severely or cut all the way back to the ground after the leaves have dropped. Since the flowers come from the current year’s stems, you will not inhibit blooming. In fact, this type of hydrangea will have more and bigger flowers if cut back. All of the hydrangeas listed in my chart bloom on new wood.

Dry Them:

Hydrangea flowers are great for drying but if picked too early in the summer, the flowers will shrivel up. Wait to cut the blossoms until later in the summer or early fall and use them to decorate your home all winter!

Flower Color:

The blossoms of white hydrangeas cannot be changed to pink or blue by lowering the Ph of your soil. However lowering your soil’s pH does change the blossom color of some pink hydrangeas to blue.

Pests and Diseases:

Hydrangeas have few pests and diseases. Some species of hydrangeas are susceptible to Japanese beetle which, lucky for us, is not a problem in Montana at this time. Protect hydrangeas from deer.

Have a shady spot on the north or east where a beautiful small shrub will work? Plant a hydrangea!