Hydrangeas are full-sun to partial-shade plants that appreciate moist, well-drained soil; however, lots of organic matter will certainly help. Although the nicest hydrangeas I have seen were on Nantucket and Martha’s Vineyard in virtually pure sand, I suspect it’s simply the moisture that’s the key — so water them copiously! Here, you’ll learn quick tips about pruning and other factors that affect color, growth and health.
Pests and Disease
While the list of diseases (wilt, blight, leafspot, rust) and pests (rose chafer, scale, mites and nematodes) seems daunting, I have never actually seen any of these, and don’t expect to. I have seen powdery mildew, but this is easily controlled with benomyl, oil or lime sulfur (the latter two will discolor blossoms). Generally the biggest problems with this plant are siting and culture, so find a sheltered, partly shaded spot, water regularly, and soon your summer and fall will be filled with hydrangeas.
Hydrangeas can be the backbone of most summer borders. Their cultural requirements lend themselves to combining with roses (in a full-sun situation; both need plenty of water), weigelia, spirea, and many other summer flowering shrubs. Let’s not forget the perennial border; there are any number of possible combinations there. All in all, hydrangeas are a versatile plant that deserves a place in your garden.
The other big question with feeding hydrangeas is flower color. Acidic soils give us blues and baser soils cause pink flowers. The key is aluminum ions in the soil, so aluminum sulfate is a good quick fix, but prolonged use year after year may cause a fatal buildup in the soil. Iron sulfate is a safer fix, or try alternating. If pink is what you want, top dress with dolomite or drench with a quick lime solution.
Failure to Flower
Hydrangeas fail to flower for several reasons. Most common would be frost damage, followed very closely by late pruning. Too much shade or nitrogen are other likely culprits, but let’s look at siting our plant and pruning as our best controls. If your hydrangea is not flowering look at your growing practices and where you situate the plant, then make appropriate changes.
Don’t feed new plants until they are established (one to two months) and then use a balanced fertilizer. Feed sparingly, as too much nitrogen prevents flowering.
Courtesy of Brock Farms, Freehold and Colts Neck