Hydrangea Pleasures and Problems

Hydrangea Pleasures and Problems

Care and Questions in Early June

Our customers have many questions about Hydrangeas, so a Q&A about Cape Cod’s favorite shrub is timely throughout the year. Here are some of the concerns that we’re hearing about right now.

“Where’s the best place in the yard to plant blue Hydrangeas?”

The best location for a blue or pink Hydrangea is where it will get morning sun but afternoon shade. Late afternoon sun – after 4 PM – is fine too, but avoid full sun from 10 AM to 3 PM. Hydrangeas like well drained but organically amended soil, so create a bed that’s been improved with compost before planting. (Spreading 2-3″ of compost over the entire bed before planting is much better than only adding compost or peat in the hole.) After planting, apply an inch or two of bark mulch to help keep moisture in the soil.

Hydrangeas are not drought tolerant, so group them with other plants that appreciate regular irrigation, but set that irrigation so that it’s watering them deeply every five to seven days. Drip systems are good for these plants. (See leaf spot question below.)

Hydrangeas are not drought tolerant. They don’t do well in areas that can’t be watered.

“My Hydrangea started to leaf out in May but that growth has stopped, and that foliage is now wilting and dying!”

In early June a healthy Hydrangea macrophylla, the blue or pink mopheads that we love, should be filled with leaves. The buds that produce both flowers and leaves on were formed on canes last summer, and if they made it through the winter, they should be fairly large in early June, with the very start of the flowers visible. (See photos below.)

Sometimes, however, some of those buds formed the previous summer will appear to have made it through the winter, beginning to open in May, only to stall, wilt and die in June. As the new growth grows from the bottom of the plant, it’s almost like the plant decides to put its energy into the new stems and abandon the growth up above. This can happen when those developing leaves get hit with cold, spring winds or near-freezing temperatures. Since the flower buds are in that growth on those canes (commonly called “old wood”) this means that the plant will have fewer or no flowers this summer. Although many people wait until the end of June to remove the dead canes, “just in case they come back,” there is nothing to be done but to prune out any stems where the buds and flowers have died. Varieties such as Endless Summer or Enchantress are less prone to this problem.

Here is how the average mophead Hydrangea should look in early June. (This photo taken on Cape Cod on June 1st.) The leaves aren’t quite full-sized, but they grow larger every day, and it’s clear that they’re healthy and developing.
This is a photo taken on June 1st of a mophead Hydrangea (Hydrangea macrophylla ‘Big Daddy’) that shows how some plants start to develop leaves on the canes, only to slow or stop that growth as the bottom shoots develop. Those small leaves on the canes are no longer growing, but are wilting and dying, even though the plant is being watered. All of the bare stems should be pruned out now, before the new growth gets larger. In another two weeks, if the growth on the old canes has continued to wilt and die, they should be removed too.
In early June you should see new flowers beginning on your mophead or lacecap Hydrangeas. (It’s too early to see flowers on the white/pink panicle varieties such as Limelight.) The germ of these buds were formed in July and August of last year, which is why you should never try and make these shrubs shorter…no matter when they are pruned, if you trim them back you’ll have fewer flowers, and the plants will be just a high the following summer.

“What are the spots on my blue Hydrangea leaves?”

Hydrangeas are prone to leaf spot fungus when the leaves are frequently splashed with water. On Cape Cod, this happens early in the season because we usually have such cool, damp springs. Later in the summer this can happen if an irrigation system is hitting the leaves too often. While there is nothing you can do about the spring weather, be sure to water around these shrubs deeply but less often. If possible, use a drip system or soaker hoses around these plants.

Leaf spot is common on Hydrangeas that get hit with frequent rainfall or irrigation. This is a cosmetic problem, and doesn’t kill the plants. Unless the splashing is extreme, or continues for many weeks, leaf spot doesn’t harm the flowers. Spraying with a fungicide isn’t usually recommended, but if you think that you’d like to try treating, begin early in the season using an organic fungicide. Come into the garden center to see the range of products available.

“Why do the flowers on my Hydrangeas get brown by the end of July?”

The flowers on mophead and lacecap Hydrangeas last longest if the plants are growing in morning sun but afternoon shade. Although these shrubs will live in full sun, the flowers typically will wilt during the heat of the day when the sun is strongest. This frequent wilting causes the flowers to turn brown very quickly. The only cure is to move your plants to a place where they are sheltered from the mid-day sun.

Brown mophead flowers indicates that the plant is growing in too much sun, or that the flowers have wilted too many times from not enough watering.

“My Hydrangea flowers are opening green instead of blue. Why?”

Whether you’re growing blue or pink Hydrangeas, know that the flower color takes time to develop. It’s typical that the flowers begin to open with white, cream or greenish petals. The other colors will deepen over a period of two to four weeks. Greenish flowers early in June do not mean that you need to add aluminum or sulfur to the soil.

To see a handout about Hydrangea color, click here.

The Hydrangeas in our nursery show the range of flower color as the blooms develop. Those lime-green blossoms will become deep blue as they get older. Depth of color is genetic: pale blue flowers will either be pale pink or blue as they mature, while some varieties will be a deep blue, dark pink, or purple.

“My neighbor just planted Hydrangeas that are in full bloom, but the ones in my yard aren’t visible yet. Is there something wrong with mine?”

Most nurseries and garden centers get in plants that already have flowers on them, because customers like to see a bloom before they buy. But in May and June, these plants are more mature than the ones in the landscape. Mophead and lacecap varieties on Cape Cod begin to show color at the end of June, as do the smooth Hydrangeas such as Annabelle and Invincibelle Spirit. Panicle varieties such as Limelight, and Bobo don’t begin to flower until the end of July, although some paniculata types (Quick Fire, Little Quick Fire, and Firelight) will show flowers in the middle of that month.

Hydrangeas that arrive at the garden center are usually already in bloom, even if the shrubs in the landscape are just beginning to develop flowers in early June. Shrubs that are planted in bloom this year will flower at the same time as others in coming seasons.

“How can I learn more about Hydrangeas?”

Since this is Cape Cod’s signature plant, we offer many educational sessions throughout the year about these plants. Watch our Events page for upcoming classes and virtual happy hours about Hydrangeas. You can also join the Cape Cod Hydrangea Society to get information about their meetings and newsletter. Watch for the various events and open gardens during the Cape Cod Hydrangea Festival. Hyannis Country Garden is proud to be a major sponsor of the Hydrangea Fest and will have special exhibits and talks during those ten days in July.

Whether your favorites are blue, white, pink or purple, we’re committed to supplying the best plants and the information that homeowners need for a beautiful landscape and garden.
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5 Comments

  1. Mary on June 9, 2022 at 6:47 am

    When is it ok to trim the cane on my lace cap hydrangeas?

    • CLFornari on June 11, 2022 at 9:04 am

      The only trimming you should do on these is removal of dead canes. Do not trim them down. There is no way to make them shorter, and if you time them back they will be just as tall by mid-summer with far fewer flowers. Best time to remove dead parts is late May, but you can still do that now.

  2. Martha Meier on June 9, 2022 at 7:11 am

    Great article – very informative!

    Thank you!
    Martha Meier
    North Chatham, MA 02650

  3. Cat logan on June 9, 2022 at 7:43 am

    Very helpful information , clearly explained and illustrated. I have several types of hydrangeas. My one hydrangea that is having difficulty is the one with variegated leaves. It seems that slugs or some insects are particularly attracted to the variegated variety. Any truth to that?

    • CLFornari on June 11, 2022 at 9:02 am

      Cat,
      Yes, the white parts on many variegated plants are favorites for earwigs and slugs, to name just two. You can dust with Diatomaceous Earth (DE) to try and stop the damage. Dust on dry day when rain isn’t expected

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