Answer: Either would grow well in your gardening zone so choosing which will be a challenge. I like 'Penny Mac' because of the colorful fall foliage. Aside from that, both are wonderful additions to almost any landscape. Here is some background information:
Mophead hydrangea 'Penny Mac' (Hydrangea macrophylla 'Penny Mac') is named for Penny McHenry, the energetic founder of the American Hydrangea Society, 'Penny Mac' is a mophead-type hydrangea that re-blooms until frost. Covered with masses of light- to medium-blue balls that measure seven inches across, 'Penny Mac' has a vigorous habit and grows rapidly to five feet tall by equally as broad. The deciduous shrub produces bright blue--and sometimes deep purple--flowers until knocked down by frost. The fall foliage is a mix of purple, burgundy and dark green. Hardy in USDA Zones 5 to 9.
How to use it: Plant in masses at the edge of a woodland garden or line a path on both sides of a stroll garden. This is also a good accent plant and fits well in a cottage garden. 'Penny Mac' is a great cut flower, but before you take cuttings, be sure to wait until hydrangea blooms have been on the bush for a while. The season's first flush of brand-new blossoms will not hold up well when cut.
Cultivation: 'Penny Mac' is an ideal choice for gardeners in colder climates since it sets buds on new wood. Like other hydrangeas, 'Penny Mac' will appreciate well-drained soil, protection from afternoon sun and plenty of good, dark compost. Be sure to apply even moisture to all hydrangeas; they don't tolerate drought. To propagate, simply lower a branch to the ground and secure with a brick. It is advisable to scratch the stem where it makes contact with the soil to encourage faster rooting.
Endless Summer is a mop-head type hydrangea with the unique ablity to bloom consistently on both old and new growth. The result is a plant that provides beautiful flowers all summer long. It is hardy to zone 4 climate with floewers up to 8" in diameter. Pink blooms in alkaline soils and blue blooms in acidic soils. Since Endless Summer Blooms on new wood, removal of spent flowers will encourage rebloom.
Endless Summer produces spectacular pink or blue blooms depending on the makeup of your soil. If you don't know the pH content of your soil, ask your garden center for a soil testing kit. Alkaline soils (pH 6-7) will produce pink blooms. More acidic soil (pH 5-5.8) will turn your blooms blue. To lower the soil's pH, add a soil acidifier to the soil before planting. Follow the directions on the package to encourage blue blooms throughout the season.
To encourage rebloom, remove spent flowers. Because Endless Summer blooms on new growth, you don't have to wait until the next season to see armfuls of new blooms.
Hope this information helps you select just the right hydrangeas!
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