How to Grow and Care for Tardiva Hydrangea

Tardiva hydrangea is a shrub best known for its long-lasting and color-changing blooms. This panicle hydrangea variety grows best in warm to temperate climates, in a location that receives full to partial sun and offers rich, well-draining soil to support the plant’s vigorous blooming habit. 

Like other hydrangea varieties, the stems, leaves, and blooms of these plants are toxic to people and pets, if ingested.

Tardiva Hydrangea Care

To grow tardiva hydrangea, follow these basic principles of care for this plant.

• Plant in rich soil that is moist but well-draining.
• Choose a planting location that receives at least three to six hours of sunlight each day.
• Water regularly, when the top inch of soil feels dry.
• Fertilizer is generally not needed, but a slow-release formula can be applied in the spring.

Light

Tardiva hydrangeas will grow in full sun to partial shade conditions. While more sun generally translates into better flower production, it’s important to note that the plant should receive a measure of shade in areas with strong afternoon sun exposure.

Soil

Like other hydrangeas, these plants prefer acidic soil, with a pH range between 6.1 and 7.0. The soil should be nutrient-rich to support the shrub’s growth habit and flower production. If soil quality is lacking, it may be beneficial to add a layer of compost to the soil environment. 

Water

It’s important to regularly water tardiva hydrangeas, especially during periods of drought or hot weather. The abundant foliage of these spreading shrubs requires plenty of moisture to avoid wilting and drooping. At the same time, beware of overwatering. To help avoid doing so, water when the top inch of soil becomes dry. In addition, well-draining soil is important to avoid soggy, wet roots that can lead to rot. 

It’s generally best to water these plants from the base, rather than saturating the dense foliage and flowers, which can lead to fungal infection.

Temperature and Humidity

With a growing zone that stretches as far north as Minnesota and as far south as Georgia and Texas, these perennials can withstand cold and hot temperatures. They prefer average-to-high humidity levels.

During the growing season, tardiva hydrangeas do best with warm temperatures during the day and cooler temperatures at night. In warmer regions of the plant’s growing zone, they will need increased watering and shade protection from the intense afternoon heat.

Fertilizer

Panicle hydrangeas, including the Tardiva variety, generally do not need to be fertilized as much as other hydrangea varieties. You may not need to fertilize these hydrangeas at all, but applying a slow-release granular fertilizer in the spring can boost bloom production. Be sure not to overfeed these plants with nitrogen, as this can cause elongated stem growth, which makes the stems weak and prone to drooping under the weight of the blooms.

Pruning

Tardiva hydrangeas bloom on new wood, so always prune these plants in the late winter or early spring, before new growth appears. These plants tolerate, and even benefit, from vigorous pruning that removes up to half of the old growth.

While this hydrangea variety typically grows with multiple stems and offshoots that contribute to its natural use as a landscaping shrub, it can also be pruned to grow as a tree. If that’s your aim, prune the plant to remove all offshoots, leaving only a central stem. You may need to stake the stem to support it through the first few years of growth. As the plant grows, remove any new growth offshoots, except for those at the crown of the central stem. It can take several years of pruning to develop a hydrangea tree; as an alternative, you can often buy one at a nursery that has already been cultivated into a tree-like shape.

Propagating Tardiva Hydrangea

Similar to other hydrangea plants, it’s easiest to propagate tardiva hydrangeas using stem cuttings. Since the plant is generally vigorous and fast-growing, cuttings taken in the spring won’t have much of an impact on the parent plant and the new cutting will usually mature by the fall.

You'll need sanitized pruning shears, sterile potting mix soil, 8 to 10-inch pot, rooting hormone (optional).Here’s how to propagate tardiva hydrangea using stem cuttings:

1. From your hydrangea plant, identify a green, new-growth branch without buds. Make a cut using the pruning shears 2 inches below a leaf node, creating a stem cutting that is 6 to 8 inches long. Repeat if you would like to grow several cuttings at once.
2. Remove the lower leaves on the stem cutting, leaving one or two pairs of leaves at the top of the cutting.
3. Fill the pot with the soil mix. Dip the end of the stem cutting in root hormone, if desired. Plant the cutting in the pot, with the base of the leaves at the soil line. You can plant several cuttings in a single pot.
4. Moisten the soil and place a clear plastic bag over the pot. Place it in bright, indirect light.
5. Monitor the soil and water as needed to keep the soil moist, but not overly wet.
6. The cuttings should develop roots in about 4 weeks. Once evidence of root structure is present, transplant the cutting to a new pot with soil mix or, in the case of well-developed cuttings, into the garden. 

Overwintering

Tardiva hydrangea is hardy in USDA growing zone 3, which means that it can withstand temperatures well below freezing, even as low as -40 degrees Fahrenheit. As one of the hardiest types of hydrangeas, no special preparation is necessary to overwinter this perennial shrub, but you can insulate the roots with a layer of mulch if desired.

How to Get Tardiva Hydrangea to Bloom

Panicle hydrangeas, including the tardiva cultivar, are prized for their cone-like clusters of flowers. You can add a tardiva hydrangea to your cut flower garden if you want to snip the large blooms for summer or autumn bouquets.

Bloom Months

Tardiva hydrangea typically blooms from late summer to early fall. You can expect to enjoy flowers on the shrub from July to September.

How long does Tardiva Hydrangea Bloom?

The blooms of the tardiva hydrangea are notably long-lasting. You can expect the flowers to last for about two months. As a perennial flowering shrub, the flowers will reappear each summer. To encourage vigorous reblooming of tardiva hydrangea, be sure to give the plant a hard prune in the late winter or early spring to clear old growth and make room for the new growth from which the plant will flower. 

What do Tardiva Hydrangea Flowers Look and Smell Like?

The flowers that appear on tardiva hydrangea plants come in cone-shaped clusters. Each cluster measures about 7 inches long and is made up of small individual blossoms with four to five petals each. Initially, the flowers are white in color but gradually take on a pink hue before turning a dusky red in the fall. Unlike other types of hydrangeas that change bloom color based on soil pH, the tardiva hydrangea changes color in response to cooling temperatures.

Common Problems With Tardiva Hydrangea

As a cultivar of the easy-going panicle hydrangea, the ‘Tardivia’ variety has a reputation for being simple to grow and care for. However, gardeners should be on alert for some of the most common problems of tardiva hydrangea, since early intervention is usually the best way to avoid more widespread plant problems.

Few or No Blooms

If your tardivia hydrangea isn’t producing very many blooms by the middle-to-end of July, it’s likely that the plant has experienced trauma or is suffering from sunlight deficiency. The most common cause of few or no blooms on a tardiva hydrangea is poorly timed pruning. While it’s true that this hydrangea benefits from aggressive pruning, it only produces flower buds on new wood. If you inadvertently prune new growth from the hydrangea plant, you will see reduced flower production because of the bud loss.

If you’re certain that pruning isn’t to blame, then your tardiva hydrangea may not bloom because of insufficient sunlight. Panicle hydrangeas are particularly fond of full sun. While the plant will grow in partial sun, less than six hours of sun may result in reduced bloom activity. At a minimum, the plant should be in a location that receives three to four hours of sun.

Plant Leaves Wilting

While it’s not unusual to see the heavy flower panicles cause the tardiva hydrangea’s stems to bend, wilting of the plant leaves is a separate problem that merits your attention. If the leaves of the normally large, lush foliage of this plant appear limp and wilted, it’s likely a sign that the plant isn’t receiving the right amount of water.

In the case of overwatering, the plant leaves may also turn yellow. The roots may emit a foul odor if root rot has also begun. If the hydrangea is underwatered, the leaves will feel dry and crispy, perhaps with brown, shriveled edges.

Leaves With Spots

In the case of some fungal diseases, the leaves of the tardiva hydrangea plant may develop spots. Powdery mildew looks like gray, fuzzy patches on the leaves of the plant. It’s most common with dense plants that are in somewhat shady conditions with high humidity levels. Thinning the plant’s foliage may improve air circulation but one of the best things you can do is water the plant from the base, rather than spraying water onto the leaves or flowers.

If the leaves are developing dark purple spots, it is likely the early stages of a Cercospora fungal infection. It’s best to remove and destroy impacted leaves and you may need to treat the plant with a fungicidal spray. Moisture usually is the carrier and facilitator of this condition, so follow similar steps as listed above to prevent the onset of powdery mildew.