Light
Grow these bushes in full sun at the northern end of their hardiness zone (zone 3) and in partial sun at the southern end of their hardiness zone (zone 8).
Soil
Make sure that the soil drains well. If the soil is not well-drained, before planting amend the soil with compost to improve drainage.
Water
The shrub has average water needs, but you should irrigate it to keep the soil consistently moist. Do not waterlog the soil.
Temperature and Humidity
You’ll see the best growth out of your hydrangeas when the daytime temps are near 70 degrees Fahrenheit and the nighttime temperatures don’t drop below 60 degrees Fahrenheit. Several weeks of temperatures consistently below 65 degrees in the fall will allow buds to set, which encourages profusions of blooms. It will go dormant in temperatures below 45 degrees Fahrenheit. It can handle a wide range of humidity levels.
Fertilizer
Fertilize Zinfin Doll hydrangea bushes annually in spring with compost or manure tea.
Pruning
Prune back Zinfin Doll hydrangea by about 1/3 annually in late winter or early spring if you wish to treat it as a multi-branched shrub. This bit of landscape maintenance not only helps keep the bush compact but also stimulates new growth. New growth is what you want on these shrubs because Zinfin Doll hydrangea, like all panicle hydrangeas, blooms on this year’s new wood. Reducing the number of branches can cause the flower heads to grow bigger, as well. As an alternative, you can also prune the plant to train it to take on a tree form.
Propagating Zinfin Doll Hydrangeas
These hydrangeas are best propagated through cuttings, which are often a ready success. In early fall, cut stems that are at least 6 inches in length, made of all new growth but with no flowers. Cut the stem just below a leaf node, making sure there are at least two leaves left above the node. Cut those two leaves in half, crosswise. Dip the cutting in rooting hormone and plant it in a small container with damp soil. Cover the pot with a plastic bag, making sure the bag doesn’t touch the cutting. Keep it in an area where it receives indirect sunlight and make sure the soil stays damp. In two to four weeks, your cutting will be ready to plant.
How to Grow Zinfin Doll Hydrangeas From Seed
Hydrangeas rarely produce seeds, so the best way to create more plants is through cuttings, or purchasing new plants at your local nursery.
Potting and Repotting Zinfin Doll Hydrangeas
It is possible to grow hydrangeas in pots. Choose a pot that is at least 12 inches in depth and width to allow for the spreading root system. To ensure the best possible drainage and prevent root rot, add a bit of gravel, marbles, or other medium to the bottom of a pot that already has several drainage holes. Mix a slow-release fertilizer into high-quality potting soil. Hydrangeas need to be repotted every one to two years. To do this, choose a pot that is a few inches wider than the last one. To prevent shock to the plant, repot only in the autumn after the last blooms have faded.
Overwintering
Prune back the hydrangea by about 1/3 to get rid of old wood and encourage new growth. Though well-established hydrangeas can do just fine without any special care for the winter, smaller shrubs can benefit from several inches of mulch over the roots, as well as a cage surrounding the plant that is filled with leaves or pine needles to help insulate it from snow and ice.
Common Pests and Plant Diseases
Panicle hydrangeas can suffer from bacterial wilt, blight, leaf spot, powdery mildew, and rust. To prevent these diseases from attacking your plants, make sure they are spaced far enough apart, about 4 to 6 feet on center. Proper spacing allows air to circulate more freely, which reduces the chance of these diseases. In terms of insect pests, be on the lookout for aphids and spider mites. Inspect the undersides of the leaves to make sure these pests are not present. If you do find any, spray the undersides of the leaves immediately with Neem oil, which is an organic pesticide. Happily, Zinfin Doll hydrangea is a deer-resistant shrub.
How to Get Zinfin Doll Hydrangeas to Bloom
Remember that Zinfin Doll, like other hydrangeas, presents blooms on new growth. The easiest way to ensure plenty of new wood is to cut back the shrub at the end of the growing season. Pruning by about 1/3 and cutting out dead branches can help maintain the shape as well as encourage new blooms. If the hydrangea offers a disappointing bloom season, rejuvenate the plant by cutting it back to about 6-12 inches above the ground in the fall.
