Hydrangeas are a favorite perennial shrub due to their showy flowers that make excellent cut flowers for arrangements or dried floral accents. Although many varieties are considered hardy, meaning they fare well in many environments and conditions, this is rarely the case. Hydrangeas prefer specific soil types and locations, particularly those that stay moist and get either morning or filtered sunlight, and those locations that can remain moist without staying overly wet. Most pink hydrangeas can switch to blue, lilac or purple flowers depending on the soil's pH. White hydrangeas prefer a neutral or alkaline soil.
Hydrangeas require well-drained, humus-rich soil that stays fairly moist -- but not wet -- all the time. Because of the moisture requirements, an area that receives only morning sun or filtered sunlight throughout the day is best. A shadier spot keeps the soil cooler and retains the moisture better than full-sun areas. Hardy hydrangeas that growers claim are suited for full-sun environments must be in an area where the soil does not get overly dry and hot, which can be difficult in some climates. For pink hydrangeas, you'll also need a sweet soil, or one that is alkaline. The sweeter the soil, the pinker the blooms.
Sweetening the Soil
Before you sweeten the soil or even before planting your hydrangeas, test your soil's pH. Test kits or services are often available through your county extension offices offered by local universities. The tests can vary in price. Pink blooms require a pH of 6.0 or more. Neutral pH is 7.0, while anything higher than this is considered alkaline, and anything lower than this number is considered acidic. To sweeten the soil, or make it more alkaline, add lime sulfur to your soil, according to the package's instructions. White hydrangeas don't require sweetening for the color; simply place them in the right location and take care of them throughout the seasons for ideal blooms.
Amending the Soil
Because the hydrangeas require well-drained, humus-rich soil, amending your soil ensures excellent blooms and foliage as well as the general health of your plants. Loam and sandy-loam soils are ideal because of the amount of drainage. Clay soils, on the other hand, will hold too much water. Adding compost to your soil will not only help with drainage but will also feed your hydrangeas as the compost continues to break down. Quality peat moss is another amendment, particularly if your soil does not drain well. Mix peat moss into your planting site at a ratio of approximately 80-percent soil to 20-percent peat moss.
Hydrangeas are quick to show signs of water deficiency -- quicker than many other plants. The leaves will begin to wilt, leading to an unpleasing appearance, and the blooms may suffer and begin to droop as well. During the first growing season, water your hydrangeas every third day for at least 20 minutes. Feeding hydrangeas an organic all-purpose fertilizer, applied according to the package instructions, is also an ideal way to ensure your hydrangeas are getting everything they need. If your blooms are sparse or non-existent, consider feeding with a fertilizer that has higher phosphorous; phosphorous promotes bud and bloom development and helps with photosynthesis and root health. Poor bloom quantity may also be related to not getting enough sunlight through the day or from pruning -- many hydrangeas bloom on old growth and common pruning techniques may get rid of the buds the plant has set for the season.
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