7 Hydrangea Autumn Care Tips to Boost Next Year’s Blooms

Hydrangeas are gorgeous plants that add color and structure to any space. They require attentive care to look their best, though. Here are the best hydrangea autumn care tips to get the best blooms next spring and summer.

Top Fall Hydrangea Care Tips

1. Know the Different Types of Hydrangeas

There are dozens of species of hydrangeas, and not all of them require the same type of care! To give your plants the best care possible, it's important to familiarize yourself with the main four varieties of hydrangea: oakleaf, panicle, bigleaf, and smooth.

Oakleaf Hydrangeas

• Species: Hydrangea quercifolia
• Also called: Oak-leaved hydrangea
• Wood bloom type: Old wood
• Popular cultivars: Snow Queen, Alice

Panicle Hydrangea

• Species: Hydrangea paniculata
• Also called: Panticled hydrangeas
• Wood bloom type: New wood
• Popular cultivars: Limelight, Grandiflora

Bigleaf Hydrangea

• Species: Hydrangea macrophylla
• Also called: Mophead hydrangeas
• Wood bloom type: Mostly old wood (some cultivars bloom on old and new wood)
• Popular cultivars: Lacecap, Endless Summer®

Smooth Hydrangea

• Species: Hydrangea arborescens
• Also called: Sevenbark
• Wood bloom type: New wood
• Popular cultivars: Annabelle, Incrediball®

In addition to these four main types, it's also important to distinguish between new growth/new wood and old growth/old wood varieties. New wood bloomers are hydrangeas that grow on stems from the current growing season, whereas old wood bloomers are those whose flower heads grow on last year's stems. Some species and cultivars may experience both old growth and new growth.

2. Water (But Don't Overdo It)

Hydrangeas in the fall benefit from watering every week or two. Watering should only occur when the soil is already dry, and needs to take place in the morning, close to the base of the plant.

3. Mulch

Hydrangeas benefit from fall mulching, especially old growth varieties. Organic mulch, composed of material like shredded bark and pine needles, works well for most hydrangea varieties.

4. Amend the Soil

Some varieties of hydrangea are more likely to bloom certain colors of flowers based on the pH of their soil; acidic soil encourages blue flowers and alkaline soil encourages pink flowers.

A digital soil tester or pH strip kit can help you check soil pH. Once you know the pH of your soil, you can do the following:

• To encourage blue hydrangea flowers: Aim for acidic soil (pH of 6 and under) by adding aluminum sulfate to the soil.
• To encourage pink flowers: Aim for alkaline soil (pH above 7) by adding lime to the soil.
• To encourage either (or purple flowers): Leave soil alone if it's at a neutral pH (7).

5. Prune Hydrangeas at the Right Time

Hydrangea pruning and deadheading timing and practices can vary based on the type of hydrangea you have.

Old growth varieties, like oakleaf and bigleaf, benefit from pruning after summer flowering. New growth varieties, however, benefit from pruning into late winter or even early spring.

6. Hold Off on the Fertilizer

Fertilizing hydrangeas is best left for the next spring and should not be part of routine fall hydrangea care.

7. Protect the Plant

Some varieties of hydrangea, like Annabelle and Limelight (i.e., new wood bloomers), don't require much, if any, protection in milder climates.

Old wood bloomers, however, do require some winter protection to save stems and flower buds from harsh conditions like frost.

Potted hydrangea winter protection is as easy as moving the plant indoors to a basement or unheated garage. Outdoor plants, after mulching, require protection like a burlap wrap or a wire frame (with an open top) with insulating material (like fallen leaves).

Hydrangea Autumn Care FAQs

Should I cut back my hydrangeas in the fall?

When you should cut back on and prune your hydrangeas depends on which type you have.

If you have old growth hydrangeas, it is best to not cut back (or prune much at all, outside of removing dead or diseased plant material) in the fall, as these hydrangea varieties rely on old stems for next season's blooms. The best time for cutting back old growth hydrangeas is after new flowers bloom, typically occurring in summer months.

If you have new growth hydrangeas, pruning and cutting back can occur in late winter or even early spring, as these varieties do not rely on old stems to bloom.

What is the 1/3 rule for hydrangeas?

The 1/3 hydrangea rule states that you shouldn't ever remove more than a third of the plant's mass at a time.

Can I cut back old wood hydrangeas?

Old wood hydrangeas usually don't benefit from cutting back on a large scale, unless there are lots of dead or diseased plant material. Instead, it's often best to simply prune lightly after new hydrangea blooms occur in the summer.

Do hydrangeas need to be fertilized in the fall?

No.

The best time of year for fertilizing hydrangeas is usually early spring.

Do hydrangeas need mulch in the fall?

Yes, many species of hydrangea benefit from autumn mulching.

How do you winterize hydrangeas?

The good news is that you don't have to winterize all varieties of hydrangeas, like new growth types (e.g., smooth, panicle) unless you expect a particularly harsh winter. Old growth hydrangeas, like oakleaf and bigleaf varieties, do require some winterization to protect flower buds and stems from frost.

Winterizing these types of hydrangea typically involves mulching their bases, watering until first frost of the season, lightly pruning spent flowers, and then covering a burlap sack or wire cage with leaves for extra insulation.

Proper hydrangea autumn care can be time consuming. When you don't have that time, contact the experts with decades of experience caring for St. Louis-area greenery: Poynter Landscape Architecture & Construction.