When it comes to shrubs, hydrangeas continue to rank No. 1 with many Michigan homeowners. Unfortunately, the Holy Grail many Michiganians yearn to grow in their gardens is the bodacious mophead, also called Big Leaf or florist hydrangeas (H. macrophyllas), sporting large clusters of pink, red or blue flowers. Under the right conditions, these fabulous flowering shrubs can rise to 5 feet or more in height with a spread of 6 feet, and are breathtaking in bloom.

I will forever lust for the fabulous deep-blue specimens I encountered at Dan Hinkley’s famous Heronswood garden in Washington state and the gardens of Oregon. Unfortunately, the chances of growing them to that size and color in my Michigan garden are nil.

If sited carefully in a protected area, folks who dig in Michigan’s Zone 6 banana belts, such as the Grosse Pointes and the southwestern coastline of Lake Michigan, where lake effect tempers harsh winters, may have some success. But the rest of us have to make due with bushel-basket-sized plants that get beaten up every winter and bloom sporadically, if at all, if we don’t protect them in winter and spring.

The simple answer as to why these shrubs fail to flower is their tender flower buds form in fall on year-old wood, and when exposed to freeze-and-thaw conditions and winter winds, they dry out and die. If it’s a harsh winter, the entire plant may die back to the ground. Bottom line, folks: no buds, no blooms.

Mophead hydrangeas thrive in gardens where the winters are wet and mild, so we’re pushing the envelope trying to grow them here, but that’s what gardeners love to do.

The recent introduction of Endless Summer and several other mophead varieties that bloom on old and new wood threw hydrangeaholics into a frenzy. While these new varieties do bloom throughout the summer, the blossom heads are smaller and lack the depth of color of those produced by the old classic Nikko Blue, the beauties Martha Stewart has in her garden.

But even these plants need to be kept in tiptop condition. They do best in the morning sun. Hydrangeas crave moist, organically rich, well-drained soil. So if your hydrangea is plunked under a huge maple tree, move it. Amend soil that lacks organic matter with 3 inches of peat moss, compost, well-aged manure, shredded leaves and/or composted pine bark.

Keeping the soil moderately moist is key. Hydrangea guru Michael Dirr, author of “Hydrangeas for American Gardens” (Timber Press $29.95), recommends providing 2 inches of water weekly, divided into two waterings, depending on the weather.

When plants don’t flower, most gardeners douse them with fertilizer. Unfortunately, excessive fertilizer will not make these plants bloom. It will, however, promote soft, lush growth that is subject to winter kill and frost damage. Dirr recommends applying 4 ounces of a slow-release fertilizer in late winter or early spring before the leaves emerge. Scatter it around the base of the plant out to the drip line

I use Perennial Nurture, which is 70 percent organic and laced with beneficial organisms (bacteria) and kelp. The bacteria help to break down the fertilizer into a form that is best for the plant.

Winter protection is the best way to ensure the mopheads bloom from year to year. Inverted over the shrub, a large gray plastic garbage can with its bottom removed makes a great winter cubbie. If the plant is too wide, gather up the stems and tie them together with old nylons or clothesline. Then fill the can with autumn leaves. Tomato cages wrapped in burlap and stuffed with leaves will also work.

When spring arrives, the covers should be removed, but watch for cold winds and freezing temperatures of a late frost that can quickly desiccate and kill the tender flower buds.

The past couple of winters, we have suffered hard frosts in May that zapped the flower buds of many plants with a history of successful bloom.

When frost threatens, covering the plants with an old sheet, a floating row cover or a cardboard box will usually provide enough protection to keep the buds from dying.

Spraying the flower buds with an antidessicant such as Wilt-Pruf may also afford a bit of protection over the winter, but in early spring, it must be re-applied often to protect new growth. And be forewarned that when temperatures drop below 5 or 10 degrees, it loses its effectiveness, so using it for winter protection may not do the job.

For more information on the selection and care of all your hydrangeas, check out hydrangeaholic Judith King’s Web site at www.hy drangeashydrangeas.com.

Marney Rich Keenan’s column will return. Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Saturdays in Homestyle. E-mail her at Szerlag @earthlink.net. You can also read her previous columns at detnews.com/homestyle/. For more gardening tips check out her blog at www.gardeneryardener.blogspot.com.