Big leaf hydrangeas provide a wonderful range of flower colors in shadier locations. Colors range from white to blue with all shades of pink, red, and purple in between. There are incredible color combinations such as red and green, pink and white, and many more. This type of Hydrangea can be more particular about where it will grow but it will reward your care and attention to placement with colorful and profuse flowers all summer long.

The Perfect Location

In areas that are warmer and less exposed, no winter protection may be necessary if you choose a variety that is hardy to your zone. The varieties we carry at Chuck Hafner’s are all hardy in zone 5 (-20 ̇) with some being hardy to zone 4 (-30 ̇). Always check the labels to make sure you have a variety that is hardy to your zone.

Part shade with protection from hot afternoon sun – Examples would be an eastern exposure or along a wood line. If placed in too much sun, such as a southern exposure, or during extreme summer temperatures, Hydrangeas may wilt. If the wilting becomes too severe the foliage may scorch despite the soil is moist enough. Always check before watering to see if it is needed. You can spritz the foliage to help cool it down.

Moist, well-drained soil – While these plants are tolerant of many soil types, they can be a bit picky about soil moisture with the preference being moist, well-drained. Be careful not to overwater if the shrub is wilting on very hot days or in too much sun. Fertilize in the spring to maintain optimum nutrients in the soil for best performance.

Flowers!

Flowers differ by variety in form, color, and whether flower buds are set on old or new wood.

Form – There are two forms of flowers, mop heads, and lace caps. The mop heads are large, ball-shaped clusters of flowers. The lace cap, as the name implies, has a lacey, more open look. It’s a round, flat-topped cluster of smaller flowers in the center surrounded by larger flowers on the outer edge.

Color – Flower colors are either independent of soil pH or determined by soil pH with more acidic soils yielding blue flowers and more alkaline soils yielding pink. Purple flowers will occur in soils with a pH between acidic and alkaline. Varieties of hydrangeas where flower color is independent of soil pH are typically white or red.

Flower buds on old wood versus new wood – An important fact to know about these types of hydrangeas is that they produce flower buds either on old wood or on both old and new wood.

• Old wood – If they produce flower buds on old wood, the buds are set in summer on current year’s growth, overwinter, then bloom next summer. While hardiness has improved greatly, it’s important to provide winter protection to ensure those flower buds survive the winter so you will have flowers the next summer.
• New Wood – If flower buds are set on both old and new wood, flower production is much more reliable. These varieties are called rebloomers and will bloom most of the summer. Even if the old wood flower buds freeze, you will still produce flowers on current year’s growth provided there hasn’t been a severe late spring freeze.

Why won’t my Hydrangea bloom?

One of the most frequently asked questions about this type of hydrangea is why it won’t bloom. While this is much less of an issue in the last 10 years due to improved varieties, there are several reasons why these hydrangeas would fail to bloom.

• Hardiness – The first question we would ask is what variety it is. A Hydrangea that continuously sprouts new growth from the crown, grows nice and lush every year, but never blooms may not be hardy in CNY. This is a common complaint with florist’s Hydrangeas and some older varieties such as ‘Nikko Blue’ which were commonly planted 10 years ago. These are varieties that set flower buds on the previous year’s growth (old wood). The flower buds are not hardy and freeze over the winter.
• Late spring frosts – A late spring freeze can kill the new growth back to the crown. For that year, there may be no flowers.
• Not enough sun – Hydrangeas prefer part sun but if planted in deep shade, it will not set flower buds.
• Lack of soil nutrients – If the soil is nutrient deficient, flower performance will be affected. Fertilizing yearly will boost flower production.
• Removal of flower buds – Animals such as rabbits or deer may remove the buds before flowering. Pruning at the wrong time of year will also have the same effect, no flowers.

Maintaining a Happy Hydrangea

Pruning – This should be done primarily for cleaning up stem dieback in early spring before the new growth fully emerges. This isn’t a shrub where size can easily be controlled by pruning since the stems come directly from the crown and don’t branch as many other shrubs do.

Fertilization – To keep your Hydrangea looking great and flowering profusely, fertilize with a time-release granular fertilizer. There are fertilizers specifically formulated for Hydrangeas that will increase flowering and help acidify the soils for darker blue flower color.

Maintain soil pH for the desired flower color – Soil pH can be changed using aluminum sulfate for acidity and garden lime for alkalinity. Apply what’s needed in the spring once you have tested the pH to determine what’s needed.

Protection from extreme winter cold – In cold, windy locations we would suggest that winter protection covers the plant. It will also help reduce damage from late spring frosts which can hurt new growth. Mulching deeply, 8” to 12”, will protect the crown. Several layers of burlap wrapping the top will help protect the upper branches.

Picking the Perfect Hydrangea

While the flowers are an obvious characteristic in selecting a Hydrangea, there are several other factors to consider. Mature size and hardiness are equally important. The best way to ensure you don’t have an oversizedHydrangea is to plant a variety that will be the right size at maturity. Sizes range from 2’ to 5’, so there’s a Hydrangea to fit any landscape where they’ll grow well. Also, consider the hardiness zone your garden is in. If you choose a Hydrangea that is hardy to your zone, there will be less maintenance required since there will be less pruning, and winter protection may not be necessary.