There are many kinds of hydrangeas! The commonly known ones can be blue or pink, depending on the soil pH. If the pH is from 6.5 to 8.0 (alkaline), the flowers will be pink, but between 5.0 and just under 6.5 (acid), they'll be blue!

Most soils in the southeastern Michigan area will produce pink flowers. Some lime, which makes the soil more alkaline, will intensify the pink color.

To acidify the soil, add some Cottonseed Meal, Garden Sulfur or Aluminum Sulfate.

When aiming to change the pH of the soil, it is good to run a pH test to see where you stand before starting. Kits are available at garden centers.

Potted hydrangeas are one of the touchiest plants I have experience with. A lot of sites say that they are sensitive to drought, and that drying "may", "shorten the life" of the plant. HA, HA, HA!!!

I'll put it bluntly. If these plants dry up for one minute, it's INSTANT, IRREVERSIBLE DEATH!!! If you have these in the house, you either need to be superhumanly concientious, or have an automatic watering device similar to the kind you'd find on the lawns of both fine and cheap hotels. Capillary matting, pots with reservoirs, and even gizmos that use old 2-liter pop bottles to drip water through a tube are all good ways to keep a plant wet with little work.

Outside, they're not much different. They need a semi-shaded spot, but not TOO shaded. If it's too shady, they won't bloom. The leaves will burn if they get too dry, so automatic sprinklers are advisable. If you don't have automatic sprinklers, you'll need to get out there with a hose--in the heat of summer, most likely daily. Make sure the water isn't just running off the top of any mulch you put on--stick your hand WAY down in there to make sure the water is getting to the ROOTS of the plants!

Some hydrangeas form their buds in the spring, and some in the fall. Your safest bet for pruning is to prune them right after they're done flowering, since they won't have had the chance to start forming new flower buds at that time.

Blue Hydrangea Bush--Bigleaf Hydrangea
From the NC Cooperative Extension Office

It is suggested that hydrangeas last longest as cut flowers when cut in the early morning (blegh!). As that "blegh" implies, early morning is not a time I experience on purpose! Therefore, I have learned some tricks for getting flowers from mid-day until the middle of the night: For mid-day, the best time to cut (for long lasting flowers) is during a drizzle. This will have hydrated the plants almost as much as a cool night.

Disease, however, LOVES to spread like mad in the wet. Therefore, extra precautions must be taken to preserve both the health of your plants, and your sleep! Make sure to sterilize your hands and tools with extra care. Also, avoid jarring the plants, to avoid causing invisible little scratches (only visible with a microscope), which allow disease in. The cut you make on purpose isn't usually the opening disease uses--there is much more surface area left open by the microscopic scratches which are caused by jarring, walking by and hitting the leaves, etc. (The only plant I can think of not to try this with is the Zinnia. They're too susceptible to powdery mildew even with the most stringent of precautions.) If you have a high amount of plant disease in your area, don't cut when wet even with precautions!

But, under average to low disease conditions, if you're careful, you can get your flowers at mid-day in a drizzle with no problems.

Another alternative is to harvest them late at night (when the weather is dry). When it just gets dark, the plant is "tired" and hasn't replenished its water or the nutrients responsible for long flower life.

But if you're up after 1 in the morning, the flowers will last almost as long as a morning cutting. And if you can stick it out till 3 AM, that's morning enough! That's just as good as a 7 AM cutting (I find it much easier to just stay up than to get up early)!

When hydrangeas get old, they sometimes stop flowering, or severely reduce the amount of flowers produced. This can be due to an overabundance of nitrogen, too much shade, mistimed pruning, generally poor soil, and cold temperatures, which kill the buds of some varieties.

Besides the blue/pink varieties with the ball-like blooms, there are varieties which bloom with masses of white flowers (commonly planted in the frigid states), and ones with elongated blooms.

If you live in a southern state, you may be interested in the North Carolina Cooperative Extension Service's page here, which is where I got the soil pH requirements, and the outdoor growing conditions.

For more extensive pruning instructions, check out the Care Sheet provided by Bordine's Nursery in Michigan. (PDF File)