The Hydrangea is a native of Japan, but seems to do well just about everywhere. Hydrangea make gorgeous landscape shrubs in the proper setting. They have specific requirements for good growth and flowering, requiring an organic, well-drained soil in partial shade. I've read recommendations that hydrangea be grown in full sun, but that just will not work here in central Florida. They need protection from the afternoon summer sun. Morning sun is great, though.
Hydrangeas do need lots of water. Check them often and feed lightly with an acid fertilizer every other month beginning in March and continuing through September.
I've tried both mopheads (big, plump flamboyant blossoms) and lacecaps (flattened, delicate blossoms with a lacey texture). The mopheads stick around, the lacecaps have disappeared. Some of my hydrangeas have lilac flowers (not enough aluminum sulfate) and some have pink flowers (no aluminum sulfate added to the soil). While the blue flowers are lovely and I usually try for them on a couple plants, I also love the huge vibrant pink blooms.
My potted hydrangea started life as a Mother's Day gift. The first summer outside it produced small pink flowers. That winter a freeze damaged the plant. Since hydrangeas set flower buds in the fall, the freeze took care of any flowers the second summer. For this same reason, don't prune hydrangeas after July because you will be cutting off your next summer's flowers.
For pink flowers, sprinkle 3 to 4 cups of lime around the base of the plant. Do this again several months later. For blue flowers, add 4 tablespoons of aluminum sulfate to a gallon of water and drench around the base. Do this again in three weeks. Don't expect overnight success. It will take up to a year to turn the color from pink to blue, or if you prefer, from blue to pink
To get the largest flower clusters, reduce the number of stems; or if you prefer medium flower heads, let your hydrangea grow as it pleases.
If you want to cut your hydrangeas to enjoy inside, you should condition them. I've read that florists will use a small hammer to crush the bottom of the stems, but you can cut an extra inch from the bottoms to ensure they will absorb enough water. Remove any leaves that could end up below the water line. Keep the arrangement out of direct light, add cold water to the vase daily, change the water if it gets cloudy and your arrangement will look lovely for more than a week.
The following article appeared in Florida Today, July 19, 2003...
Help keep hydrangeas healthy
Hydrangeas are high on horticultural drama and frustration. Some plants never bloom. The flowers won't turn blue, or pink. The shrubs always wilt in the afternoon. In short, everybody else's hydrangeas do better than yours.
Here are a few hydrangea basics:
- Prune only in the two-week period after bloom fades. If you don't have blooms, don't prune for at least a full season.
- White hydrangeas won't turn blue or pink.
- Always give hydrangeas morning sun and afternoon shade.
Cultivation of hydrangeas is fairly easy if you keep them out of full anything. Full sun makes them wilt. Full moisture makes them rot. Full dryness makes them die. Full shade makes them weedy and elongated. Again: morning sun/afternoon shade. If you must grow in full sun, select only the PeeGee hydrangeas, but be prepared to keep them well watered.
Do not plant directly under trees to provide shade. The trees invariably suck up moisture and nutrients, and the hydrangeas decline. Plant them out beyond the drip line of the tree.
Propagation is easy. Cuttings taken in June and early July should root readily. Use branches that did not flower this year. Remove the lower leaves from each 6-inch cutting, and cut the remaining leaves in half. Dip the bottom end of the cuttings in rooting hormone and stick in a dampened soilless mix. Water well one time, and cover with a temporary plastic greenhouse made from a bag or whatever. Place the pot on the north side of the house, out of direct sun. Water only when the top of the soil is dry. It should be rooted in a month or less.
It is not possible to turn every hydrangea a different color. You can't change white hydrangeas to blue or pink even though many white hydrangeas do get a pinkish blush as the flower ages.
You can change big leaf hydrangeas that are blue to pink and the pink ones to blue if you are willing to fiddle around a lot. It is almost impossible to turn a pink more intense pink, or what is called redand looks red in many color photographs in gardening books.
It is easiest to make changes to hydrangeas grown in really big pots than it is to hydrangeas grown in the yard.
For blue: Add aluminum to the soil by adding aluminum sulfate solution throughout the growing season.
For pink: remove aluminum from the soil by adding lime several times a year.
This is not a simple as it sounds. Aluminum usually is present in the soil in some degree, and your job for blue flowers is to acidify the soil so the aluminum is more readily available.
To change a blue one to pink, remove aluminum - keep it out of the plant's reach by adding enough lime that the soil pH is 6 or slightly higher, on the more alkaline side.
If you naturally have blue flowers, you know your soil is high in aluminum, and you will be rowing upstream to try to change your blue flowers to pink unless you are willing to pot up the hydrangeas and adjust a soilless mix in that pot.
PeeGees: This is H. paniculata, so called for its panicles of blooms, more cone-shaped than round. The best known is H. paniculata Grandiflora. This is the one that set off the habit of calling all H. paniculata hydrangeas PeeGees. They are lovely with a vaselike, upright habit rather than spreading like other hydrangeas.