HYDRANGEA PLANNING

January 2025 was the warmest January on record globally despite having the coldest January in New England since 2014. Our string of consecutive days and nights in the single digits spells doom for big leaf hydrangeas (macrophylla) that flower only on old wood. It will even be a challenge for mountain hydrangeas (serrata) and their oak leaf cousins (quercifolia) and climbers (petiolaris) that also flower only on old wood (sigh) but are slightly more hardy. Here’s where rebloomers will really earn their keep: so glad I added them to my garden.

WHAT YOU CAN DO NOW

That knowledge of what deeply cold winter temps will do to my garden, however, also gives me the insight to plan ahead. So let’s translate those plans.

First, be prepared to examine your old wood bloomers closely early in the season. As soon as you are confident that they won’t be giving you early season flowers, you can freely cut them back. This is not only an opportunity to shape them (without penalty) but also to stimulate new growth. For the rebloomers, that cutback will also accelerate the big leaf and mountain hydrangea schedules to hurry along and produce those reblooming flowers.

Point on hydrangea stem where new growth happens (nodes)

Coupled with the cutback should be a second fertilizer application, again to help the plant produce the resulting new growth (flowers as well as stems). Of course, irrigation is a critical success factor for this regrowth and reblooming cycle. A dry season will seriously arrest the growth power of these plants so pay attention to rainfall and/or your irrigation practices.

Rose-tone fertilizer is an excellent product for hydrangea health

THE IMPORTANCE OF COMPANION PLANTS FOR HYDRANGEAS

A sparse hydrangea flower display is an ideal time to take a closer look at what you have planted around your hydrangeas. A lack of hydrangea flowers could be an opportunity to bump up your companion plants. If you have hardy perennials, they should have no problem emerging and flowering on schedule so make it an even better show. Now is a good time to get those orders in for plants you may want to add.

The Usefulness of Daylilies

You can successfully marry daylilies (Hemerocallis) with hydrangeas. They will flower a little less vigorously if they are on the shady side so site them as best you can. This photo is a classic Van Gogh scheme of orange and blue. You could even add a hydrangea arborescens in the background where there is more shade. It can provide color contrast to set off the flowers of the big leaf hydrangea. The fence in this photo does exactly that.

Orange daylilies and variegated phlox used as companion plants for blue flowered hydrangeas

That Van Gogh combo gets better when you add the variegated foliage of Phlox paniculata ‘Nora Leigh’ (on the right) to the mix. The phlox brightens the shade and sets off the orange daylilies and blue hydrangeas. The large, hydrangea-like flower clusters of this phlox create a spectacular show in the garden. You’ll get fragrant white flowers with a contrasting pink eye, and boldly variegated leaves, splashed with green and creamy-white. Even when it’s not in flower, it makes a great garden accent.

For a dramatic combo, try a white flowered hydrangea like this Hydrangea macrophylla Double Delights™ Wedding Gown with a dark flowered daylily. Here you see the impact of daylily ‘Midnight Raider’. The daylily has stunning, large reddish-purple blooms with luminous yellow centers surrounded by white flares. It will re-bloom in late summer for a spectacular color accent. Unlike other daylilies, its grass-like foliage stays green throughout the season.

Dark flowered daylily used as companion plant for white flowered hydrangea

Boxwood

You could also “box your hydrangeas in” using boxwood in any number of ways, e.g., as a border. The best part is that boxwoods can provide winter protection for tender hydrangea buds. And, they add winter interest to the landscape when hydrangeas lose their leaves. If you are not a boxwood fan, you can always use hollies (Japanese and otherwise). There are a number of other small evergreens that can do the job as well.

Boxwood used as border for big leaf hydrangeas

Japanese Forest Grass and Clematis

Using Japanese Forest Grass with a blue-flowering big leaf hydrangea is a popular combination as shown below.

Big Leaf Hydrangea With Japanese Forest Grass

Things get more interesting later in the season when the clematis ‘Etoile Violette’ comes into flower on the trellis. Its deep purple flowers contrast nicely with the golden grass and blue hydrangea flowers. Any deeply colored vine can be substituted for the clematis.

Clematis used as companion plant for big leaf hydrangea

Consider Using Small Trees

If you’ve got too much sun for your big leaf hydrangea, plant a small tree like a Kousa dogwood or a sumac. This one is Tiger Eyes® Cutleaf Staghorn Sumac. It has that fabulous fine golden foliage all season long and can provide much needed shade for your smaller hydrangeas. Like all sumacs, it tolerates a wide range of soils as well as urban conditions. It will even work in either poorly drained soils or very dry soil. As magnificent as the summer colors are, the dramatic effect of the sumac comes in fall. It is something to see as it turns yellow, orange and intense scarlet in the cooler temps of autumn.

The golden foliage of this sumac is a carefree hydrangea companion plant

Hydrangea serrata companions

Hosta ‘Guacamole’ is a stunning companion for any blue flowered hydrangea. Here you see it with mountain Hydrangea serrata ‘Blue Billow’ as its yellow tinted foliage sets off the flowers. The bold foliage of the hosta contrasts well with the delicate look of the lacecap hydrangea flowers to create a garden show-stopper. The hosta’s huge, glossy, apple green leaves are surrounded by streaked, dark green leaf margins just like an avocado. Leaf centers become a brighter gold in summer when exposed to more sunlight while the margins remain dark green. The hosta’s pale lavender flowers are very fragrant late summer additions to the garden.

Hosta ‘Guacamole’ used as companion plant for blue flowered hydrangea

As long as we are talking about mountain hydrangeas, this combination is an attention grabber. The delicate lacecap hydrangea flowers are accented by the bold foliage of the Japanese Forest Grass (once again). But then we have the added contrast of the purple Heuchera and variegated foliage of the Lamium.

Japanese Forest Grass used with other perennials as hydrangea companion plants

What to do in lieu of plants

Maybe your site won’t accommodate another plant. That opens the door to use ornaments to serve the same purpose of highlighting your hydrangeas. A well-placed small statue or similar item might be just what is needed.

Use ornaments instead of hydrangea companion plants

Or maybe even an artfully arranged fence corner.

Hydrangea serrata ‘Bluebird’ in full bloom

Find the right companions for your hydrangeas

When choosing companion plants or ornaments for your hydrangeas, think about maximizing color, adding textural interest, and extending bloom time in your garden. With the right pairings, these combinations  can provide months of beauty.

Upcoming Public Talks/Presentations

Audience listening to speaker

This is a new year and I am continuing to book talks, both virtual and live. If you are interested in having me speak to your group, just click HERE and you will be taken to the “Contact Me” page of my site to begin our dialogue. I cover lots of other topics besides hydrangeas, as you will see when you click on “Speaking Topics.” All my talks are 5-star rated, so you won’t be disappointed. Here are my upcoming public dates:

February 16, Southeast Connecticut Home and Garden Show, 11 a.m. Earth Expo and Convention Center, Mohegan Sun, Uncasville CT. Show admission fee. “Hydrangeas!”

March 1, New York Botanical Garden, Bronx NY. Weatherproof Hydrangeas, 10 a.m.-12 p.m. Fee Based.

March 9, New York Botanical Garden, Bronx NY. 11 a.m. – 2 p.m. Pruning Big Leaf and Mountain Hydrangeas. Fee based.

March 26, Greenwich Botanical Center (GBC) 10 a.m. Safe Solutions to Gardens and Landscapes. Fee based.

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Thank you!

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Thanks for reading!