PeeGee hydrangeas are normally hardy and grow quickly.
Hydrangea Paniculata, or PeeGee hydrangea, can grow from a small, closely tended shrub to a small tree 15 to 25 feet tall and 10 feet wide. They tend to be fast-growing and produce large panicles of white flowers in mid-summer, which turn pinkish to near purple as the blooming period progresses. In the proper place in your landscape and with the proper soil, PeeGee hydrangeas should produce healthy growth throughout the growing season.
Soil
PeeGee hydrangea prefers rich, loamy soil that is moist but well-drained. It will tolerate boggy soils but prefers acidic soils with a pH somewhere around 4.5. Alkaline soils will retard plant growth.
Pests and Diseases
PeeGees are vulnerable to honey fungus, rust, sooty mold, powdery mildew and blight. Fungal infestations should be treated in the early spring with a fungicide according to the manufacturer's instructions. Hydrangea growth can be impaired by aphids and scale, which can be prevented with a regular spraying program or by washing the leaves with soapy water or an insecticidal soap. Fungus or parasitic insects can reduce the strength of the plant and stop growth.
Sunshine and Weather
Hydrangea paniculata does well in full sun or part shade and grows best along the edge of a sunny wooded border. They can tolerate a little less sunshine, but the foliage may not be as lush, nor the flowers as heavy. Full sunshine is anything over six hours a day. Part shade is anything between tree and six hours. Anything less reduces the growth potential of hydrangeas. They tolerate heat but must have some moisture deep down at the root tips. Hydrangeas can tolerate winter temperatures as low as -25 degrees Fahrenheit, but hard late spring frosts can kill new plant growth for the rest of the growing season.
Pruning
PeeGee hydrangeas bloom on new stems, so you cannot prune them while they are producing buds and blooms in spring and summer. Prune the branches once they finish blooming in the summer and before they begin adding new growth in the spring. If you prune them too close to the ground, the steps won't add thickness and the heavy blooms may break down the stems. You can train the PeeGee hydrangea as either a shrub or a tree form if you allow the trunk and main top branches to develop. Cutting back excess branches may help reduce the stress on an under-developed root system and allow the plant to come back and grow the following season.
Fertilizing
PeeGee hydrangeas, once well-established, will benefit from fertilization every few years if grown as trees. In a shrub forms, they should be fertilized annually, but only after a soil test to determine if any nutrients are low. Don't use a general fertilizer as too much of some nutrients can retard hydrangea growth. If you are having trouble with growth, a high nitrogen fertilizer promotes green leafy growth but in excess will cause leaf and branch growth at the expense of flower bud development. Fertilize early in the season. A late application can force lush growth late in the season, which doesn't leave time for the plant to harden before winter. This can add a load of weak or dying foliage that slows growth in spring.
Watering
It is important for hydrangea paniculata to develop a broad root system. If the plants are not growing, build a water ring around the base of the shrub consisting of raised, compacted earth over the original planting hole. This causes rain and irrigation water to run off from around the base toward the outside of the ring. This encourages the roots to reach outward toward the ring of moist soil outside the mound. Mulching over the mound also helps preserve moisture.
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