The beauty of a hydrangea blossom is unmistakable, so it’s no surprise that it’s the second most planted ornamental for your garden. The variety of colors and shapes of the flowers, all luscious in hue, are long-blooming (‘Hydrangea means “A show for all seasons”). The plant is versatile in design, beautiful in arrangements for your home, while having few insect and disease problems.
Here’s a guide on the types of hydrangeas, along with a few care tips:
There are dozens of varieties of hydrangeas, with three basic flower types:
- Mop heads: large ball-shaped blooms
- Lace cap: flat blooms with clusters of tiny flowers in the center
- Panicle: cone-shaped blooms or paniculata grandiflora varieties.
Incrediball Smooth Hydrangea arborescens
There are six different species of hydrangeas commonly grown in North American gardens. Though they all share the genus Hydrangea, each one has unique characteristics that differentiate it from the others:
- Bigleaf Hydrangeas (Macrophylla) are the belle of the ball. With their big pink, purple or blue ball-shaped flowers, this is the plant that most people mean when they say “hydrangea.” Hardy to USDA zone 5.
- Panicle Hydrangeas (Paniculata) are some of the easiest, most rewarding plants you can grow. Also known as “pee gee” hydrangeas, they flower every year, and their blooms begin white of green before maturing to a beautiful pink, burgundy or red color. Super hardy – USDA zone 3.
- Oakleaf Hydrangeas (Quercifolia) are true four-season hydrangeas. They have handsome oak-like leaves, big showy white flowers in summer, amazing fall color, and attractive peeling bark in winter. Native to North America and hardy to USDA zone 5.
- Mountain Hydrangeas (Serrata) are closely related to Bigleaf hydrangeas, but are more tolerant to cold. Their flowers are also pink or blue, but a bit smaller and flatter than their showier cousins. Hardy to USDA zone 5.
- Climbing Hydrangeas (Anomala petiolaris) are vines that clamber up trees or walls with tiny clinging roots. They have white flowers and are relatively slow-growing. Hardy to USDA zone 5.
- Smooth Hydrangeas (Arborescens) are North American natives with large orb-like clusters of white, pink or green flowers. They are easy to grown, reliable and very hardy, thriving, even in USDA zone 3.
Let’s Dance Diva! Hydrangea macrophylla
Site Selection When you’re determining where you’ll plant hydrangeas, walk through your yard and make note of existing plants, spacing availability, areas that need splashes of color and amount of sun. The farther north you are – Zones 4-5a – the more sun your hydrangeas can handle.
Endless Summer Blue Hydrangea macrophylla
Soils and Amendments Amending Your Soil: Prior to planting anything in your garden, it’s best to get a soil test to determine what amendments you may need.
- Sandy soils can be considered an asset after a long or hard rain, because they drain quickly. The drawback is that they won’t hold a lot of moisture and nutrients for plants. It’s best to add some peat to the soil when planting.
- If you have clay soil, it is best to amend the soil with a pine soil conditioner that will “break up” the clay as it breaks down and becomes organic matter in the soil.
- If you prefer pink blooms, your hydrangea should be deprived of aluminum by growing it in an alkaline soil. You can apply a high-phosphorus fertilizer to further discourage the uptake of aluminum.
- Espoma Garden Lime can be used to help raise the pH of your soil (making it more alkaline and less acidic). Add this in the fall as it takes several month for the effects to be noticeable.
- Espoma Soil Acidifier can be used to help lower the pH of the soil around Macrophylla hydrangeas (i.e. Endless Summer Hydrangeas) to turn pink blooms to blue. It can take up to two years to change color. Apply two to three times during the growing season.
- Aluminum Sulfate helps to create an acid soil environment for plants and will help to intensify the blue color in Hydrangeas. Since aluminum sulfate is diluted into water, the results can be visible in a couple of days when turning Macrophylla hydrangeas blue (i.e. Endless Summer Hydrangeas). This should be done as the blooms are just starting to open.
- Pour the aluminum sulfate solution around the plant’s drip line. To keep the blue color all season, this application should be done two to three times during the growing season. Follow the manufacturer’s directions so you don’t over fertilize.
Expression Hydrangea macrophylla
Liquid Fertilizers Once the plants are blooming, a liquid fertilizer such as English Gardens Bloom Booster can be applied once a week to the plants for additional nutrients.
Planting Hydrangeas Once your soil is prepared, lay out the plants in your intended design. Be sure to keep in mind full mature size of the plants, ensuring that they will barely touch at full size. This will make your garden look full, while allowing air to still circulate through the garden.
- Dig your hole two to three times wider than the pot size
- Place any fertilizer or nutrients needed to improve soil mix in the hole before putting your hydrangeas in place. Use a starter fertilizer, such as Espoma Plant-tone and Espoma Bui-tone Start Plus.
- Make sure that the crown of the plant (where the base of the stems meets the soil – is even with the ground level. If the hydrangea is placed too high, it can easily dry out.
Gatsby’s Gal Oakleaf Hydrangea quercifolia
Watering Hydrangeas prefer well-drained, moist soil, but not wet; overwatering can cause hydrangeas to produce less flowers.
- In very warm weather, hydrangeas may wilt a bit in the afternoon, but will revive when the temperatures cool down. You can assist with this by watering in the morning or evening when the wind is more still and the sun less hot.
Overwintering It’s a good idea to protect your plants form freezing winter temperatures.
- Leaving the fall blooms on your plants over the winter provides winter interest, and ensures you aren’t removing buds that will become flowers in the spring and summer.
- Leaves, mulch or straw are good options to insulate your plants. Mound the mulch or leaves around your plants at least 12 inches high to protect the flower buds that will bloom early next year.
- In the spring, don’t remove the mulch too fast; wait until all danger of frost has passed before uncovering to ensure beautiful blooms from old and new wood.
- The “old wood” buds will provide early season color and the blooms forming on current season growth will typically occur roughly six weeks later and last through the end of the season.
Pruning is one of the most important factors for successful hydrangea blooms. The key factor is whether the plant blooms on new or old wood.
Old wood Bigleaf Hydrangeas (Macrophylla) and Oakleaf Hydrangeas (Quercifolia) bloom on old wood. These plants produce flower buds on stems from August to October for the following summer’s blooms. If these stems are bloomed in the fall, winter or spring, the bloom buds will be removed, and there will be little or no bloom the following the summer.
New wood Smooth (Arborescens), Panicle (Paniculata), Climbing (Anomala Petiolaris), and Mountain (Serrata) hydrangeas bloom on new wood. These plants produce flower buds in the current season, beginning about a month or two before they bloom. Therefore, they can be pruned any time after they bloom and up until they begin producing flower buds.
It is always best to choose a plant that most closely fits the space it will occupy. This will keep pruning to a minimum.
If in doubt, only prune off old flower heads and leave the rest until spring. Once June arrives, you’re safe to prune off any stems that have not produced leaves.
Learn more about The Best Hydrangea for Michigan Gardens