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Dotting the landscape near rural farmhouses and alongside suburban homes, the hydrangea plant is a snap to grow—as long as you know how and when to plant hydrangeas, and which types of hydrangeas to use in your area. Knowing when to plant gives your hydrangeas a strong start and helps them establish a robust root system. And healthy plants produce the finest show of flowers. Below you’ll learn the two best options for when to plant hydrangeas as well as get tips on choosing the right site, how to plant, and after planting care.
What are hydrangeas?
Hydrangeas may have an old-fashioned feel, but there are now well over 1,800 cultivated varieties, including dwarf types like Wee Bit Giddy bigleaf hydrangeas and cut-flower favorites such as Little Quick Fire. Ranging from just a foot tall to a whopping fifteen feet or more, there are hydrangeas for nearly every use. And, if garden space is at a premium, you can even grow this classic shrub in pots on your deck, front porch, or balcony. Drawn to those long-lasting, traditional-looking snowballs? The old-school mophead variety is likely for you. Want to help local pollinators? Consider a lacecap like Endless Summer Twist-n-Shout or a panicle-type like French Manicure. Both the lacecap hydrangea and panicle hydrangeas offer a mix of tiny clusters of true, fertile flowers in addition to their colorful-but-sterile sepals.
You can also support another very unusual, specific pollinator by planting Hydrangea arborescens. Cold- and drought-tolerant, these native, smooth hydrangeas play host to the Hydrangea Sphinx moth, a colorful moth that grows up to 3 inches across.
Why is knowing when to plant hydrangeas important?
If you want to give your hydrangeas the best possible start, they’ll need to have ample time to establish healthy roots before the stifling heat of summer hits and well before Old Man Winter comes knocking, too. That’s why knowing when to plant hydrangeas relative to your local climate and growing conditions is so important.
How to determine when to plant hydrangeas based on where you live
In part, the choice you make regarding when to plant hydrangeas will be determined by your location’s climate. If you live somewhere with harsh winters, wait until your last average frost date has passed before planting in the spring. If you prefer to plant your hydrangeas in the fall, get them in the ground several weeks before your first average frost.
But what if you’re based in a warm climate with a long growing season and mild winters? In USDA hardiness zones 8 or up, you’re not as likely to lose your hydrangeas to biting winter weather. In Zone 8, for example, low temperatures are 10 to 20 degrees F (-12.2 to -6.7 degrees C.) As a result, you have a longer planting window and could plant either in late winter or very early spring. (That said, however, you’ll need to be sure your hydrangeas are well-established before extreme heat or drought occur.)
Common types of hydrangeas
Just as local climate should inform your decision about when to plant hydrangeas, it can also factor into which hydrangea varieties you choose.
- Hydrangea paniculata—Featuring slightly cone-shaped flowers, this cold- and drought-tolerant variety thrives in full sun and can even grow in clay-heavy soils.
- Hydrangea macrophylla—Also called bigleaf hydrangeas, these plants can tolerate heat, shade, and wet feet a bit better than others.
- Hydrangea serrata—Good in shade and suitable for container gardens, this more compact grower doesn’t tolerate wet feet or very hot weather well.
- Hydrangea quercifolia—Known as the oakleaf hydrangeas, these plants can be picky. They perform best in just-right conditions that are warm, sunny, and moist.
- Hydrangea arborescens—Native to North America, smooth hydrangeas can handle drought, cool temperatures, and dappled shade well. One thing H. arborescens won’t tolerate? Prolonged soggy conditions.
Two options for when to plant hydrangeas
Wondering when to plant hydrangeas for optimal results? Early spring or fall are best. (In fact, as long as your soil is workable and the hydrangeas to be planted are still dormant, you may even be able to plant them in late winter.) Your objective is to provide the hydrangeas with ample time to put down roots—before extreme hot or cold weather hits.
Spring hydrangea planting
If you live somewhere with harsh winters, you should wait until your last average frost date has passed before planting hydrangeas in the spring. If you have milder winters, you can plant your hydrangeas earlier.
The most important point to remember about when to plant hydrangeas? Hydrangeas planted in the spring must have enough time to become established before conditions become very hot and dry.
Fall hydrangea planting
As for fall hydrangea planting, it’s best to get plants in the ground while your soil is still workable and your first average frost date is several weeks away. Essentially, you want to time things so that your hydrangeas are able to get past any transplant shock and settle into their new digs before the onset of very cold weather.
Choosing a site to plant your hydrangea
Just as important as figuring out when to plant hydrangeas? Deciding where you’ll put them, of course. You’ll need to consider the mature size and growth habit of any varieties you have your eye on. Then take a hard look at the growing conditions you are able to provide. Hydrangeas’ basic needs include:
- Full sun to partial shade—Hydrangeas like full sun, provided it’s not too hot or harsh. Morning sun combined with some afternoon shade is ideal.
- Adequate moisture plus good drainage—Your planting site should provide just the right balance of moisture and aeration. If the soil is very heavy or heavily compacted, your plants’ roots are more likely to rot and die back. And in soils which drain much too quickly, thirsty roots can become overly dry. Soil containing lots of organic matter will hold moisture and permit oxygen to reach plant roots.
- Soil pH—The pH of your soil can affect the color of your hydrangea blooms. Hydrangea varieties with white flowers will do best in soil with a neutral pH. If you have naturally high acid soil, hydrangea types with pink flowers will thrive. If, on the other hand, your soil is more alkaline, hydrangeas with blue flowers will look their best. You can check your soil pH with a pH tester and tweak pH levels as needed with soil amendments like sulfur or lime.
- Shelter—Some of the larger hydrangea types are susceptible to wind damage. For extra protection, consider planting these near a building foundation, sturdy garden wall, or fence.
Not sure you can provide just the right site? You can always plant hydrangeas in large, well-draining pots instead.
How to plant a hydrangea bush
Hydrangea root systems are relatively shallow and widespread, so the planting hole you prepare for them should be shaped accordingly. Measure the width of your plant’s root ball and then add two to three feet to that. This is the width of the bed you’ll dig.
As for the depth of your planting bed, you have a couple of choices. You can either match the height of the plant’s root ball exactly or dig an area which is just slightly more shallow. Ultimately your aim is to position the plant’s crown so that it is either even with the soil line or raised just a hair above it. Whatever you choose, take care not to bury the crown below the soil line, as this can contribute to root rot.
Hydrangeas flourish in rich, moist soil. You can give yours a strong start by amending your soil with plenty of organic matter such as aged compost, worm castings, or leaf mold. By incorporating these into the planting bed, you’ll improve your overall soil structure, help facilitate root zone aeration, and provide slow-release, organic nutrients to your hydrangeas.
Finally, once your plants are in place, water them in thoroughly and top with at least two inches of mulch. Mulching suppresses weeds and will help to keep plant roots cool and moist during summer and well insulated in winter.
For more information on when to plant hydrangeas in your garden, watch this video:
Caring for a hydrangea after planting
Whether they’ve been planted in a garden bed or in large pots, your hydrangeas will need some extra attention as they work to become established.
- Mulching—If you haven’t already done so, add a couple of inches of mulch to help protect their wide, shallow root zone. (Avoid piling mulch up against plant stems. Instead, spread it evenly beneath the full width of your hydrangea shrubs.)
- Watering—Maintaining a regular watering schedule after planting is also critical. During active growth, your hydrangeas need at least one inch of water weekly. If your plants are in an especially sunny location or you live in a warmer climate, you may need to water more frequently. That goes for container-planted hydrangeas as well. For best results, apply water to the base of your plants, and avoid wetting plant leaves. (Positioning a soaker hose directly over the root zone is a great way to accomplish this.)
- Pruning—Depending on the kind of hydrangeas you’re growing, you might choose to prune them periodically. This can improve plant health and also will enable you to influence your hydrangeas’ shape and size over time. While most hydrangeas can be pruned in early spring, you’d better determine whether your variety flowers on old wood or new wood first. (Otherwise, you might inadvertently remove next season’s flowers by mistake.)
Should you fertilize when planting a hydrangea?
Whether and when you should add fertilizer to your hydrangeas depends on factors like your hydrangea variety, the quality of your soil, and the growing conditions you can provide. Hydrangeas with extra-large, showy flower heads can be heavy feeders, but, if your soil is naturally rich in organic matter, your plants might not need any extra food. Meanwhile, container-grown hydrangeas will likely need some added fertilizer.
As a general rule, add an organic, slow-release fertilizer at least once in early spring when your hydrangea is actively growing again. If you like, you can add a phosphorous-rich fertilizer a little later in the season to give flower buds and blooms a boost.
Whatever you choose to do, avoid feeding late in the growing season. (Spurring new growth too close to the onset of cold weather can make your plants more susceptible to frost damage.)
Quick care tips for newly planted hydrangeas
As your newly planted hydrangeas are becoming established, they may be more susceptible to certain pathogens and pests. (Fortunately, once your shrubs are settled in, they’re relatively low-maintenance!) Make it a point to regularly inspect new plantings for signs of trouble. Here are 4 of the most common problems you might encounter:
- Deer damage—Deer, rabbits, and other critters sometimes will snack on new growth. You may need to put up temporary bird or deer netting to prevent their access. Over time, this should allow your plants to recover and grow large enough to withstand future light browsing.
- Spider mites—Usually more of a problem during hot, dry spells, spider mites colonize the underside of hydrangea leaves. Infested areas will appear stippled and discolored, and, if you look closely, you might see evidence of the spider mites’ fine webs. Remove and discard affected leaves and displace any stragglers by spraying the leaves with a hard stream of water.
- Aphids—These soft-bodied insects suck the life out of new stems and foliage, leaving sticky honeydew behind. Heavily damaged leaves may look curled and yellow at first. Aphids are also a vector for various plant diseases. You can hand-pick small numbers of aphids and knock back larger colonies with a hard stream of water. For overwhelming infestations, you might consider applying an insecticidal soap.
- Disease—Fungal diseases like powdery mildew, Botrytis blight, and leaf spot can wreak havoc on leaves and even flower buds. For small outbreaks, remove affected parts and use selective pruning to improve air circulation around your plants. More serious cases may require application of a fungicide.
The benefits of knowing when to plant hydrangeas
With a more complete understanding about when to plant hydrangeas, you’ll be able to get any new shrubs you add nicely situated in no time. And, because you’ve got the basics down for the planting process itself—not to mention both immediate and longterm care for your hydrangeas—your plants should have real staying power year after year.
What’s more, you’ll also be much less likely to have to fight off insect pests like aphids and spider mites or contend with leaf spots, powdery mildew, and other foliage issues. That should leave extra time for snipping hydrangea blooms for fresh cut-flower bouquets, drying hydrangeas for everlasting displays, or just watching the birds and other wildlife enjoying the benefits these sturdy-yet-elegant shrubs can provide.
For more information on growing hydrangeas, be sure to check out these in-depth articles:
- Hydrangea fall care
- How to protect hydrangeas for the winter
- Unusual hydrangeas to plant in your garden
- Are hydrangeas deer resistant?
- 3 awesome panicle hydrangeas to grow
Did we answer your questions about how and when to plant hydrangeas?
