Hydrangeas - An Old-Fashioned Shrub Enjoying a New Found Popularity!

Hydrangeas are one of the many old-fashioned shrubs are enjoying a new found popularity in gardens today! Not only is the foliage interesting, but the flower heads are stunning and provide a nice show of graceful flowers from late spring to early summer.

The Flower Style
There are three different types of hydrangea flowers

Mopheads
The most well known flower style which has a large, rounded cluster made up of hundreds of florets.


Lace-Caps
This group of hydrangeas produce flat flower clusters with a ring of larger flowers surrounding the center of smaller florets.

Panicle
This type of hydrangea includes our native varieties such as the oak leafs and the paniculatas which have large white, cone shaped clusters.


A distinctive type of Hydrangea worthy of especially noting is the Oakleaf Hydrangea. It's the only hydrangea which develops significant fall foliage color. The leaves turn a deep mahogany-red and stay on the plant until late fall. Exfoliating bark adds to winter interest. Oakleaf hydrangea is best suited used in a mixed border or as a mass planting.


Flower Color
The flower color of hydrangeas is influenced by the pH of the soil (all except white varieties) If you have acidic soil, your flowers will tend to be shades of blue. Neutral soils generally produce pale flower colors and alkaline rich soils make pink to reddish tone flowers.  These colors can be encouraged or reversed with certain varieties.  It is much easier to change a hydrangea from pink to blue than it is from blue to pink. Changing a hydrangea from pink to blue entails adding aluminum sulfate to the soil. Changing from blue to pink means subtracting aluminum from the soil or taking it out of reach of the hydrangea.

Water and Light

Hydrangeas love to be planted in soil that is moist and well drained and in a location that provides afternoon shade. Most hydrangeas benefit from some shade, especially in hot climates. Bigleaf, oakleaf and smooth hydrangeas will usually perform well on the north side of a house or planted at the edge of a woodland. Growing hydrangeas in deep shade is not necessary and can greatly reduce flowering. The amount of sun that hydrangeas can tolerate depends on species, climate and availability of water. Panicle hydrangea tolerates more sun than do other species.

Fertilizing and Feeding
Hydrangeas are heavy feeders, which means they benefit from additional nutrients. Slow release or organic products are best since they feed slowly over an extended period of time. Nutrients should be applied early in the season when the plants are just leafing out and not in late summer. A fall application can be done only after the leaves have dropped.

Pruning

Be cautious with pruning hydrangeas. Leave old flowers through the winter, as they protect the new growth tips. Spring pruning should be delayed until you can distinquish between live and dead wood. After this has been determined, you can remove some of the oldest canes over (over 4 years old and up to 1/3 of the cane). If you have an overgrown hydrangea, do a major pruning immediately after blooming. If you wait too late in the season to prune your hydrangea you will risk pruning off next year's flower buds.

Why doesn't my hydrangea bloom?

There are three possibilities for lack of flowering among the hydrangeas The first two – too much shade and improper pruning – apply to all hydrangeas, while the other – weather-related damage to flower buds – applies primarily to the bigleaf hydrangea.

While most Hydrangea species benefit from some shade, too much shade can reduce flowering. This is particularly true of panicle hydrangea, which is the one Hydrangea species that grows well in full sun. If you have a hydrangea that used to bloom well but now flowers only sparsely, evaluate whether the growth of nearby trees has reduced the amount of light that reaches the hydrangea. If so, you may want to consider moving the hydrangea to a sunnier location. Improper pruning can also reduce flowering. Since bigleaf and oakleaf hydrangeas flower on previous year’s growth, potential flowers buds would be removed if the plants were pruned in fall, winter or spring. Panicle and smooth hydrangea flower on this year’s growth, so pruning them in early summer would reduce or eliminate flowering for that year.

Drying Hydrangeas for Arrangements

One of the easiest ways to preserve these flowers is to allow them to almost completely dry on the plant. Do not collect them until the flowers have developed a papery feel. On a dry day with low humidity, cut the stems the length you need for making floral arrangements. Strip off all leaves and then find a dry place indoors where the flowers can finish drying. Some people recommend using a warm, dark location, such as an attic. Others prefer a cool, dry location. Flowers can be hung upside down while being dried, or can be placed in a vase without water.

Disease and Pests
Hydrangeas are long-lived plants and are bothered by few pests and diseases, however spider mites can colonize a plant during extended dry periods causing a type of leaf damage that looks like leaf scorch or sunburn. These pests are easy to find on the underside of the leaves. Tap the leaves on a white sheet of paper and look for pinpoint sized crawling dots.  Occasional mildew or leaf spotting occurs late in the season in humid climates. This is rarely more than a cosmetic problem.