Hydrangea care — dispelling the myths
When I was growing up, Dad would bring home a potted hydrangea for my mother at Easter time. As a rule, the plant had huge round flowers in either pink or blue and the plant would proudly be displayed on a table in the living room window.
Today, potted hydrangeas are still popular for Easter decor, but they are even more popular as garden plants, given their interesting forms, range of colours and ease of care. That being said, there are popular myths about the care of hydrangeas that my friends at the National Garden Bureau would like to clear up.
Myth 1: All hydrangeas need pruning
Fact: Pruning depends on the type of hydrangea
If you are thinking about starting to prune your hydrangeas, be aware that the rules are different for each different type of hydrangea.
Panicle and woodland hydrangea The only ones you should think about cutting back now are the panicle hydrangeas such as ‘Limelight’ and the woodland hydrangeas such as ‘Annabelle.’ These plants bloom on new wood.
If you must cut, take out every third stem of your woodland plants. Cut the rest of the stems down to about 45 to 60 centimetres tall to leave a framework to support the flower-bearing stems.
Big leaf, mountain, oak leaf and climbing hydrangeas
Don’t prune until you see those little heads of broccoli that tell you where the flowers will be. Any premature cutting you do now risks losing those flowers. These hydrangeas require very little pruning and bloom on growth from current and previous years, thus too much pruning removes potential blooms.
Myth 2: Home remedies added to your soil can change flower colour Fact: It’s not that easy to change colours
Thinking of using rusty nails, pine needles or used coffee grounds to change your soil? Not worth the effort. None of them releases anything that will help your plants.
Spreading pine needles does nothing to acidify your soil, but they are a good, non-toxic and sustainable mulch. The acid content in used coffee grounds is negligible, however, they make great mulch.
If you want to change the colour of your flowers, first be certain that a colour change is possible. Only two hydrangea types undergo significant colour changes depending on the soil: bigleaf and the less common mountain hydrangeas. Then get your soil tested to verify what it does and doesn’t need for the best plant performance.
If that test shows the pH is above 6.5 and your plant can change colour from pink to blue, add aluminum sulphate to the soil. This will lower the pH so the plant can take up the aluminum which is what turns the flowers blue. Know that it takes the plant time to absorb and move these nutrients. So your best bet is to do this in the fall to allow the plant the time it needs to work this magic.
Myth 3: 10-10-10 fertilizer is the best for hydrangeas
Fact: Shrub or rose fertilizer is best
So what kind of fertilizer should you use on your hydrangeas? Do not apply 10-10-10 or other similar products with equal amounts of nitrogen, phosphorus and potassium — it is overkill. Your best bet is a granular fertilizer formulated for shrubs or one that is a slow-release product. Rose food is ideal. For reblooming hydrangeas, it is recommended to fertilize two times a year, in the spring and summer to help the later blooms.
Myth 4: Hydrangeas need lots of water
Fact: You can overwater hydrangeas
Yes, they can droop when they are exposed to the sun (which they need), and too much water stress will negatively impact flower production. But as soon as the sun is off them, they reach back into the surrounding soil and recover. If your plants don’t perk up after they have been out of the sun for several hours, then give them a drink. Too much water can smother the roots, which will kill the plant. Oakleaf hydrangeas are especially susceptible to this.
Finally, what can we do with gifted hydrangeas? These plants are raised in a greenhouse and brought into flower months ahead of schedule for Easter or Mother’s Day. Unless otherwise labelled, the potted hydrangeas are hydrangea macrophylla, which normally bloom in the summer. This plant forms buds in the late summer that will flower the following year, on old wood. If the winter is harsh, or the plant is pruned after the winter, the buds will be destroyed and it will not flower. For now, keep the plant watered, an east facing window is ideal. Cut off the spent flowers and plant it outdoors after all danger of frost has passed. It will usually take a full year before it flowers again.