Hydrangea macrophylla

Big Leaf Hydrangea

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HYDRANGEA MACROPHYLLA (Big Leaf Hydrangea)

The genus name Hydrangea comes from hydor meaning "water" and aggeion meaning "vessel", in reference to the cup-like capsular fruit.

• A deciduous shrub with a rounded habit that typically grows 3-6’ tall and as wide unless damaged by harsh winters or pruned smaller.

• Generally features serrate, obovate to elliptic, dark green leaves (4-8” long) and large clusters of long-blooming summer flowers in either lacecap form (flattened flower clusters of small fertile florets with scattered showy sterile florets often forming a marginal ring) or mophead form (globose flower clusters of mostly showy sterile florets).

'Penny Mac' was first introduced into commerce by Penny McHenry of Atlanta, Georgia

(founder of The American Hydrangea Society)

GROWING HYDRANGEA MACROPHYLLA

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• Best grown in rich, medium moisture, well-drained soils in part shade. Tolerates full sun only if grown in consistently moist soils.

• Soil pH affects the flower color of most cultivars except white (blue in highly acidic soils and lilac to pink in slightly acidic to alkaline soils). Add aluminum sulfate to the soil to make the flowers bluer or add lime to the soil to make the flowers pinker. Begin soil treatments well in advance of flowering, as in late autumn or early spring.

• Plants generally need little pruning. If needed, prune immediately after flowering by cutting back flowering stems to a pair of healthy buds. Prune out weak or winter-damaged stems in late winter/early spring.

• Best to mulch plants year-round with 3" of shredded bark, peat or compost.

• Winter hardy to USDA Zone 6. For added protection, however, plants grown in USDA Zone 5 should be sited in sheltered locations and given additional winter protection, as needed, for the purposes of minimizing the risk of loss of significant numbers of flower buds or possible die-back to the ground in an extremely harsh winter. A burlap wrap of stems or circle of chicken wire filled with leaves or straw to 8-12" are time-consuming and visually unattractive landscape options, but can be effective. Regardless of protective measures taken, most bigleaf hydrangeas simply will not bloom (or will bloom poorly) in some years because of a variety of winter occurrences beyond the control of the gardener (e.g. low temperatures, sudden wide temperature fluctuations, icy conditions, late frosts). Some newer cultivars have been selected that flower on both old and new wood. Their pruning and flowering can differ from that of the species.

  'Penny Mac' blooms on both old and new growth and is winter hardy to USDA Zone 5. This means ‘Penny Mac’ will reliably flower each year, regardless of winter temperature or added protection.

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FERTILIZE HYDRANGEAS IN EARLY SUMMER

All hydrangeas tend to grow better when they are fertilized, even the native ones.

If you missed feeding your plants early in the season when you did your spring clean up, you can make up for that now (before August 1). The plants that respond best to fertilizer this time of year are the rebloomers: big leaf (macrophylla), mountain (serrata) and woodland/smooth (arborescens) varieties. You want to help them produce those reblooming flowers to carry your garden through to the end of the season

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