The basics of hydrangeas are pretty simple. Good rich soil that drains well, some sun but not full sun, a goodly amount of water (its leaves will droop and let you know) and a minimal amount of fertilizer.
Hydrangeas can be divided into two categories. Those that bloom on the current year’s growth, and those that bloom on old wood (last year’s growth).
The hydrangeas that bloom on old wood are from the macrophylla family. These include Nikko Blue, Endless Summer and many other pinks and blues. Blooming on old wood means that they get busy right after their blossoms fade, making flower buds for next summer. So next year when they take off growing in the spring, the flowers will emerge from the older wood, the wood that was produced last year.
But with these blue and pink hydrangeas, all kinds of things can go wrong with the flower buds. Since the flower buds are produced in August and September, they have to make it through the harsh winter before they can bloom. The flower buds can be damaged by extreme cold, which we had an abundance of this winter. I just examined my bushes and don’t see any viable flower buds. Waaah!
In contrast, the hydrangeas that bloom on new wood are typically the white hydrangeas like Annabelle and Paniculata Grandiflora (PG). They put on new growth in the spring and then the flower buds are right at the end of that new growth. That’s why the Annabelle and PG are such prolific bloomers. They set flower buds and almost immediately those buds produce big, beautiful, abundant flowers. Almost nothing can go wrong with their blooming sequence -- except if the deer nibble off the flower buds.
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Pruning? You should prune macrophylla hydrangeas right after the blooms fade, before they start making new flower buds. Annabelle and PG hydrangea and other hydrangeas that flower on new wood can be pruned during the late fall, winter or early spring before they start leafing out. Once they start growing in the spring, do not prune until after they bloom, except if there are stalks that show no green growth when the others do. The University of Illinois Extension has a good YouTube video about pruning hydrangeas. https://www.youtube.com/watch?v=wihnYCz5X3k&t=3s
Hydrangeas are not really a plant that can be divided. They are a single crown plant. I know this from personal experience. I admired a friends’ beautiful hydrangea bush with pink, blue and purple blooms all on one bush. They generously offered to help me divide it. If we had only known… one hour later, with all three of us hacking at the beachball sized iron-hard crown, produced a tangerine-sized piece of root. I am happy to report that the mother plant and my hard-won piece both survived and ten years later, my hydrangea also has pink, blue and purple blooms – when the winter freezes don’t nip it.
If you have other questions about your garden or landscape, feel free to contact a Master Gardener at the University of Illinois Extension office in Charleston at 217-345-7034. You can also check out the many horticulture webpages at the U of I Extension’s website by visiting http://web.extension.illinois.edu/ccdms/ . And be sure to like the Master Gardeners’ Facebook page, at www.facebook.com/ColesCountyMasterGardeners.
Put the GardenFest plant sale on your calendar; Saturday morning, May 11, (Mother’s Day weekend) at beautiful Lytle Park in Mattoon (Western Avenue to 32nd Street, then two blocks south), featuring vendors from Master Gardeners, Douglas Hart Nature Center and many more.