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Hydrangea Care Calendar – Part 1

Hydrangea Care Calendar – Part 1

By Stacey Hirvela, Proven Winners® ColorChoice®
Photographs courtesy of Proven Winners® ColorChoice®

It’s hard to believe we’re already halfway through 2021, but in many climates, it’s just the beginning of hydrangea season. The next couple of months are the grandest time for many hydrangea species as they come into flower, many transitioning in color as the blooms age. It is no wonder hydrangeas are some of North America’s most popular garden plants. They provide a seemingly endless display of beauty in landscapes, gardens, and vases and are surprisingly easy to grow. Nonetheless, a few pointers will help your hydrangeas perform their best throughout the year.

In this article, horticulturist Stacey Hirvela provides month-to-month guidance in caring for hydrangeas that bloom on new growth; or stems that develop during the present growing season.

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New Wood Bloomers: Panicle Hydrangea (H. paniculata), Smooth Hydrangea (H. arborescens)

March: Prune back by about one-third their total height, cutting just above a set of buds. Remove any thin, spindly side branches at that time as well. This ensures that the growth for the season will be thick, vigorous stems that grow and flower well; it also serves to remove any old flower heads still clinging to the plant. If the soil has thawed, this is also a good time to fertilize, using a granular fertilizer formulated for woody plants, like a rose fertilizer.

March is also a good time to transplant these hydrangeas if desired. This is typically a pretty straightforward job since hydrangeas are shallow-rooted. It’s best to transplant when the plants are still dormant. Save any pruning for after transplanting – that gives you the chance to repair any branches that may have broken during the moving process.

April: Fertilize if desired, one month after the previous application (if you fertilized in March). If you have deer, protect plants with a repellent or structure – though deer favor hydrangeas in general, this time of year is particularly crucial because they are very hungry, and the very tender emerging growth is extra-appealing.

May: Fertilize if desired, one month after previous application. This is also a great time to put down a good 2-3” layer of shredded bark mulch around the roots to keep them cool and moist in the coming heat.

June: Fertilize if desired, one month after previous application. You may need to begin providing supplemental water at this point if the weather is hot and dry – if these hydrangeas dry out severely during their bud development or bloom time, the flowers will turn brown and wilt instead of aging gracefully.

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July: Bloom time! There is a wide range of bloom times among both of these hydrangeas, but the earliest-blooming panicle hydrangea, Quick Fire®, Little Quick Fire® and the new Quick Fire Fab®, usually starts around July 4th, and the first smooth hydrangea usually get started a week or so later, depending on the climate and weather. While it is tempting to cut fresh hydrangea flowers to enjoy in a vase, they very often wilt if cut too fresh. It’s best to wait until the florets feel slightly dry and papery before beginning to cut.

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‘Annabelle’ smooth hydrangea notoriously flops over, especially after heavy summer storms. If this is an issue for you, plan to put up some stakes and string to provide support before it happens. You can also consider replacing your ‘Annabelle’ with one of the newer varieties that have improved stem strength, like Incrediball® and the Invincibelle® line of hydrangeas.

Because smooth and panicle hydrangeas develop interesting color that persists into fall, I do not recommend deadheading these types unless the blooms go brown, which indicates heat/drought stress.

Stop fertilizing no later than late July – fertilizing past this time can push soft growth that will simply be damaged by cold weather in a few months.

Water as needed – any drought stress will shorten bloom time.

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August: Now is a great time to cut the flowers of these hydrangeas if you wish to dry them, since they will have matured enough to not wilt right away. Whatever color they have when you cut them is the color they will stay when they are dry, so if you want, say, Limelight or Quick Fire Fab with their characteristic pink colors, wait until that develops before cutting.

Water as needed – any drought stress will shorten bloom time.

September: Flowers can still be cut, if desired.

October: Your hydrangea is most likely going dormant at this point and needs little to no attention. If your plant developed any leaf spots over the season, it’s a good idea to remove and discard the fallen foliage to minimize the chance of reinfection for next year. Though most leaf spots do not harm the plant in any significant way, they can be a bit unsightly. Add or top up mulch to maintain a 2-3” layer for winter protection.

November: These hydrangeas should be completely dormant by some time in mid-November. While I generally recommend spring pruning, since it’s nicer to look at last year’s flower skeletons all winter than a bunch of cut off sticks, it is permissible to follow the March pruning instructions to prune these types of hydrangea in late fall/early winter if you prefer, or if you won’t be around in March to prune then.

December-February: Your hydrangea is dormant and resting up for another great season. If you see any snow or ice damage to the plants over winter, don’t panic – you can easily fix it in March when you prune.

Note: in warmer climates (USDA Zones 7-9), the March-July timeline may be shifted up by as much as 6-8 weeks compared to what is laid out here, which is what you’d expect in USDA Zones 3-6.

And that’s it! Next month we’ll bring you a hydrangea care calendar for hydrangea species that bloom on old wood. Those are the oak leaf, mountain, and some cultivars of bigleaf hydrangeas. Until then, enjoy those summer blooms!

All articles are copyrighted and remain the property of the author.

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