Did you know that hydrangeas are the number one flowering shrub googled on the internet? Unfortunately, that leads to a lot of misinformation which gets perpetuated and seems to become gospel. Let’s debunk some of those myths and set the record straight.
Here are some misrepresentations:
Coffee grounds acidify the soil and help to turn your flowers blue. MYTH.
If you are talking about used coffee grounds, most of the acidity is gone from them. Sadly, there won’t be enough to change the color of your flowers. But, by using them you would recycle/compost them so to speak, a good thing. That might lead you to wonder how to apply both used and unused coffee grounds to the soil. The answer is “It all depends” since both types of coffee grounds have uses in the garden. Consult this extensive peer-reviewed paper for the details: https://cru.cahe.wsu.edu/CEPublications/FS207E/FS207E.pdf
Hydrangeas need watering as soon as you see them drooping in the sun. MYTH. It’s very normal for big leaf hydrangeas to flag from being in the sun – as normal as humans perspiring. Except, hydrangeas can reabsorb moisture from surrounding soil as soon as the sun is off them. Further, too much water can cause a plant to create leaves instead of flowers. Your best bet is to wait until the plant is out of the sun for a few hours to see if it re-hydrates. Maybe even wait until the next morning depending on where your plant is sited. If it still is drooping, only then should you give it some water. This photo
illustrates how a plant can recover as long as the surrounding soil is moist and well drained.
Cutting hydrangea flowers for home use stimulates the plant to produce more flowers. Yes, and No. If your hydrangea is one that blooms only on old wood (the stems that developed last season), cutting flowers does nothing to produce new flowers for this year. You are, however, stimulating the plant to grow new stems which can produce flowers for next year if conditions are right. If you grow a reblooming hydrangea like Endless Summer®, Bloomstruck™, Let’s Dance®, or Blue Enchantress®, the plant can produce new flowers in the current season. Tip cutting flowers on these plants will start flower production along the length of the stem for more flowers this season. Reblooming hydrangeas are one way for cold climate gardeners to make sure they have flowering plants, despite cold winters.
Fertilizing makes a hydrangea bloom. MYTH. Fertilizing per se won’t make a hydrangea bloom. The plant needs to be healthy and thriving in order to generate the energy to produce flowers. The purpose of fertilizing them is to provide the best conditions to make them strong. Hydrangeas grow especially well when fertilized in spring and/or again in midsummer if the plant is a rebloomer. Compost is an excellent amendment as is Coast of Maine Fish Bone Meal for Buds and Blooms.
You want something that is slow-release with the right mix of nutrients for your plant. This will give you a healthy, thriving plant allowing it to produce the flowers that its genetics allow.
Hydrangeas need to be pruned to flower. MYTH. Some hydrangeas need only deadheading; others can be cut to about 18 inches in late winter or early spring. Big leaf, mountain, oak leaf, and climbing hydrangeas will do just fine without ever being cut as long as they flower on old wood only. It is only the reblooming varieties that respond to “tip cutting,” an action that can generate a new flush of flowers. Before you prune, it’s imperative to know what kind of hydrangea you have. Pruning at the wrong time can take off the buds, leaving you with a green bush.
I hear this a lot: “…I followed instructions and planted my big leaf hydrangea, so it gets morning sun and afternoon shade next to the lawn. I don’t prune it except to remove dead branches in early summer and I don’t over-water it. Yet all I get is a big green bush and no flowers. Why doesn’t it bloom?”
Start by getting a soil test to check that the soil chemistry is right for this plant. It may not have enough energy to produce buds and flowers if it struggles simply to stay alive. The more likely answer is that it’s getting too much nitrogen from the lawn that’s being fertilized, especially if a rotary spreader is used and/or it is downhill of the fertilized lawn.
In that case, you might try shielding your plant and its roots when the lawn is being fertilized or change to a drop spreader that doesn’t propel the fertilizer onto your plant. Or you can transplant your hydrangea somewhere away from the lawn.
You can change the color of white hydrangeas. MYTH. If your big leaf hydrangea flower is white, it will not change color. But flower color can change on its own for panicle and oak leaf hydrangeas. In those cases those flowers will age to some shade of pink.
For traditional woodland hydrangeas, like Annabelle, the flowers will fade to a cream color and then beige but not pink or blue. There are newer varieties of woodland hydrangeas that start out in a shade of pink and hold the color for a time as they age. But there are no amendments you can add that will change the colors of either panicle or woodland hydrangeas; it’s all in their genetic code.
So the next time you use your search engine to learn about hydrangeas, consider the source. It’s always better to rely on science and not lore. That way you’ll have confidence in the info you get.
Written by Lorraine Ballato, author of Success With Hydrangeas, A Gardener’s Guide
Tags: Hydrangea coffee grounds, hydrangea watering, Hydrangea fertilizing, Hydrangea pruning, white hydrangeas