Botanical Names: French hydrangea (Hydrangea macrophylla), lacecap hydrangea (Hydrangeamacrophylla normalis), Hydrangea serrata
Plant a hydrangea shrub in your yard, and you’re on your way to a low-maintenance landscape. As beautiful as these flowering shrubs are, they aren’t too demanding when it comes to care. Feeding hydrangeas is definitely a part of the puzzle, but if you add too much hydrangea fertilizer, you risk getting heavy leaf growth and few flowers. Learn what you need to know about hydrangea food.
With most hydrangea shrubs, you should aim to fertilize in spring. Time this dose of hydrangea fertilizer for early in the season, when plants are leafing out. An easy way to give plants an early season boost is to add a shovel or two of compost around the base of plants.
You can also use a straight nursery-type fertilizer with a simple 10-10-10 formulation, which usually requires two applications — one in early spring and another in early summer. Follow package directions in terms of how much to apply and how to apply. With most fertilizers, you want to water after applying, or you can time application so it occurs just before a soaking spring rain.
Feeding hydrangeas with a product that’s labeled as a bloom booster is another option. These types of fertilizers are higher in phosphorus (the middle number) and may have a formulation like 15-30-15. The higher phosphorus content helps encourage plants to form more flower buds. This is a great fertilizer to use when the first flush of flowering has finished.
In warmer regions, feed hydrangeas a second time during the growing season, in July. In all regions, warm and cold, don’t add any hydrangea fertilizer that promotes growth after August. If you give hydrangeas food too late in summer, plants produce lush, tender growth that comes on strong right about the time hydrangeas should be preparing to go dormant for winter. This newgrowth makes the plants more susceptible to greater damage from cold winter temperatures.
There’s a crop of new specialized hydrangea soil additives on the market for changing hydrangea flower color. These products are sometimes sold as hydrangea fertilizer. They shift blossom color by changing soil pH. It’s effective with big leaf or French hydrangea (Hydrangea macrophylla), lacecap hydrangea (Hydrangea macrophylla normalis) and Hydrangea serrata.
Hydrangea fertilizers or soil additives containing sulfur lower soil pH, making it more acidic, and shifting flowers to blue and purple shades. You may also find soil acidifiers in the fertilizer section at garden centers. These products contain sulfur and often have a picture of a blue hydrangea on the bag.
To shift hydrangea blossom color to pink, look for soil lime or dolomitic lime. These products are often sold as soil additives and are usually displayed with fertilizers. The package may even show a photo of a pink hydrangea flower on the bag or bottle. With all hydrangea fertilizers, follow instructions carefully for best results.