Growing Hydrangea paniculata
Latin Name Pronunciation: hye-dran'jee-uh
Growing Hydrangea paniculata
Light/Watering: Most varieties thrive in full sun in the North, but in the South afternoon shade is required. Moist soils that do not dry out are best; do not plant in hot, dry, exposed sites. Mulch to conserve moisture and buffer soil temperatures. Avoid watering with overhead sprinklers to discourage fungal diseases.
Fertilizer/Soil & pH: Do not fertilize in the first growing season. Fertilizer is optional, once in spring with a fertilizer designed to encourage blooms (such as 15-30-15). An annual topdressing of compost is always beneficial. Soils should be moist but well drained, and rich in organic matter. Flower color is not affected by soil pH.
Pests/Diseases: None serious. Occasionally powdery mildew will infect the foliage, especially in humid areas with poor air circulation. Fungal leaf spots can occur, especially in fall when watered with overhead sprinklers, but they do not affect the overall health of the plant. Treat with Neem oil or horticultural oil, if the problem is serious, and be sure to rake up and destroy all fallen foliage in the autumn.
Pruning: Little pruning is needed, except to remove any dead or broken branches, and should be done only in winter and or early spring. Hydrangea paniculata blooms on new wood so avoid pruning in late spring and summer when flower buds are forming and getting ready to bloom. If desired, to rejuvenate an older plant, a third of the older and crossed branches can be cut back to encourage stronger branching with more numerous, although smaller, blossoms.
Tree form Hydrangea paniculata: Prune in late winter or early spring, removing lower suckers and up to half the older top growth.
Transplanting: Young plants may be transplanted when dormant in early spring. Prune top growth after transplanting to reduce water loss.
Calendar of Care
Early Spring: If desired, prune as indicated above. Feed plants (optional) with a fertilizer high in phosphorus (such as 15-30-15) to encourage blooms. Complete any transplanting before leaves unfurl.
Mid-Spring: Mulch plants after soil has warmed to conserve moisture and buffer soil temperatures. Watch for powdery mildew and treat as needed. Do not prune as doing so risks removing developing flower buds.
Summer: Do not prune in summer when flower buds form. Make sure to water well in dry weather and as flowers begin to develop. Lack of water at this time can cause blossoms to dry out prematurely and fail to develop color in varieties that display changing hues throughout the season.
Fall & End-of-Season Care: Remove and destroy any fallen foliage that could harbor disease spores. Cover the ground with up to 3" of mulch; avoid piling mulch against the trunk of the plant. Enjoy the dried flower heads through the winter, cut some to display indoors or deadhead them in late fall if you prefer, but do no substantial pruning.
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