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Hydrangea Care and Pruning—A Mystery Solved!

Hydrangeas have been a southern landscape staple for generations. With their beautiful iconic blooms and a wide assortment of shapes and colors, they have been a long-time favorite from zone 5 to 9. Some varieties are seen as far north as zone 3.

If you are like so many proud hydrangea owners, you spend your fall and winter wondering what to do with the leftover stalks. Should you cut them back? Should you leave them standing? Well, I would love to tell you the answer is the same across the board. However, it is not. What you do with the barren wood truly depends on the type of hydrangea you have. So the first step to answering this age-old question is to identify your hydrangea.

Smooth hydrangeas

Also known as wild hydrangeas, they are native to the United States. It is a large shrub, growing up to 6 feet tall. Most people will plant this as a hedge plant. Its scientific name, Hydrangea arborescens, comes from the word “arbor” meaning tree, because of its branching habits and size. Their bloom time is between June and September. Their blooms are typically white, with a round shape, and smaller than the big leaf varieties, which we will delve into next.

“Annabelle” is the most common of the smooth hydrangeas. Its blooms look like large snowballs and can grow to be twelve inches in diameter.

These beauties should be pruned back in the late winter or early spring. They will bloom on new wood, meaning the current season’s growth. Pruning them at this time encourages new growth and will result in a fuller and stronger plant so that flopping does not become a problem.

Bigleaf hydrangea

Hydrangea macrophylla are more commonly known as florist’s hydrangea, garden hydrangea and french hydrangea.

Here are two of the most common bigleaf hydrangea:

1. Mophead hydrangea

These are the most recognizable and popular hydrangeas because of their large flower head and their vibrant colors of blue, pink, and purple. This type of hydrangea is hardy in zone 7, but may not survive the freezing temperatures in zones 6 or above. However, they can be sensitive to the heat as well, so they seem to thrive in areas of partial shade. Some of them only bloom on the previous season’s growth and other, newer ones bloom on the previous season’s growth and new growth and are called rebloomers.

2. Lacecap hydrangeas

These are very similar to the mophead variety, with the main difference being in the flower itself. They have tiny, fertile flower buds in the center with flowers that circle the edge of the flower. These flowers are sterile, and their only purpose is to attract pollinators to the fertile buds. Like the mophead, they thrive in partial shade.

Mountain hydrangea (Hydrangea serrata)

These are the least common of the hydrangeas. While they are classified by many as bigleaf hydrangea, they are not truly bigleaf hydrangea. They have a classification all their own. Hydrangea Serrata looks very similar to the lacecap but has much smaller flowers and leaves. These are hardy in zone 5, making them a better choice for areas prone to late winter cold snaps. The TUFF STUFF series not only offers cold hardiness, but it has added reblooming to its beauty.

The mountain hydrangea is native to the mountainous areas of Asia and Japan where they are exposed to harsher conditions. Therefore, they are one of the hardier varieties and a solid choice if you live in an area where the winters are a little rough.

Panicle hydrangea

Panicle hydrangea has elongated flower heads. The cone-shaped panicles can range from 6 to 18 inches long. Of all the hydrangea varieties, the panicle hydrangeas are the coldest hardy and thrive in zones 4 to 7. They are one of the few that can thrive in full sunlight. They usually flower from mid to late summer, and their blooms are very long-lasting. These blooms are a great choice for drying or to use in cut arrangements.

It is best to prune these hydrangeas 1 to 3 feet tall, though you can cut them to the ground. If you leave a bit of the old wood, it can help to support the new growth and keep it from flopping as much. This should be done in late winter to early spring.

Oakleaf hydrangea

This hydrangea gets its name for obvious reasons, as its foliage is shaped like an oak leaf. Its scientific name, Hydrangea quercifolia,  literally translates to hydrangea oakleaf. Not only do the leaves bear resemblance to the oak tree, but they also change color in the fall, making it one of the most attractive choices for your landscape. The oakleaf hydrangea is one of the few hydrangeas that are native to the United States. It has white, cone-shaped flower heads that turn into a beautiful shade of pink in the fall.

These hydrangeas only require a light trim if anything, in mid to late February after the flowers and leaves are gone but before new buds set. If you trim too late, you risk cutting off blooms for the next growing season, as they begin to set blooms for the next bloom cycle almost as soon as the current bloom cycle ends.

Climbing hydrangeas

This hydrangea is exactly as the name suggests. It is a vine. It is a very slow grower and may take a long time to see it to its full potential. It has flowers that resemble those of the lacecap hydrangea and they are fragrant. Their blooms usually appear in mid to late summer. This variety prefers full to partial sun but will not tolerate full shade. This vine only needs a light trimming in the late summer or early fall when it has finished blooming.  You may trim at leaf nodes to encourage the vine to fill out. or make cuts to remove dead or damaged branches.

Fertilizing

It is best to fertilize with organic matter but if you need to apply chemical fertilizer Osmocote is a great choice.

If you are trying to improve the color of your hydrangea, you may add aluminum sulfate, composted oak leaves, pine needles, or coffee grounds to alkaline soil to get bluer blooms. To encourage pink blooms in acidic soil, add wood ashes or lime to the soil. March through July are the best times to fertilize your hydrangeas, but only do so lightly, as too much or too often can scorch your plants.

Below are some tools that we hope you will find helpful.

Go to the Proven Winner link for more information on hydrangea care: https://www.provenwinners.com/Hydrangeas-Demystified