Native to Japan and Korea, Hydrangea serrata (Mountain Hydrangea) is a deciduous shrub of rounded habit with delicate lacecap flowers with flattened clusters from early to late summer. Reminiscent of the Bigleaf Hydrangea (Hydrangea macrophylla), it is however more refined in habit and its flowers and leaves are smaller. Borne in great quantity, the elegant blossoms of some cultivars have the wonderful habit of changing color 3 to 4 times per season, a captivating process that will prevent your summer garden from becoming boring.
- Mountain Hydrangeas typically grow up to 2-4 ft. tall and wide (60-120 cm).
- Hardy to zones 6-9, Mountain Hydrangeas are vulnerable to cold but less susceptible to spring frosts than their mopheaded cousins. They welcome a good layer of mulch year-round (shredded bark, peat or compost ). This will suppress weeds, retain moisture, reduce temperature fluctuations in the soil.
- Mountain Hydrangeas prefer part shade and are best grown in rich, medium moisture, well-drained soils. They tolerate full sun only if grown with consistently moist soils. They are not as robust and tolerant of windy or hot and dry situations as the Bigleaf Hydrangeas.
- Most Mountain Hydrangeas have the added attraction of changing color, depending on the soil pH. Strongly acidic soils allow these species to produce blue flowers; slightly acidic soils will produce pink flowers. To change the color of your Hydrangea, add aluminum sulfate to the soil to make the flowers bluer or add lime to the soil to make them pinker.
- No serious pest or disease issues. Watch for bud blight, bacterial wilt, leaf spot and mildew.
- Perfect from foundation plantings to container plantings. Massed in a sheltered location or as an accent plant.
- Mountain Hydrangeas should be pruned after flowering by cutting back the stems to a pair of healthy buds. Prune out weak or winter-damaged stems in early spring.