This Is the Best Fertilizer for Endless Summer Hydrangeas

Popular bigleaf hydrangeas got a major upgrade in 2004 with the development of Endless Summer, the first reblooming hydrangea variety. Instead of producing a limited number of flowers on "old wood" from the previous year, Endless Summer continually produces new stems and new flowers. And now, the Endless Summer collection includes five unique varieties (the newest is 'Summer Crush,' a compact, container-friendly shrub with flowers that can vary from raspberry-red to vibrant purple). But that constant growth and flowering uses up a lot of nutrients, so it's important to give your reblooming hydrangeas the fuel they need, with an easy-to-use fertilizer applied at the right times in the season.

Best Fertilizer for Endless Summer Hydrangea

Feeding your reblooming hydrangea begins with finding the right product. Your local garden center's fertilizer section likely has an overwhelming number of options, so it's important to know exactly what to seek out. "You're looking for a slow-release granular fertilizer that is labeled 'bloom boost,'" says Endless Summer expert Ryan McEnaney from Bailey Nurseries. Bloom boost fertilizers, such as Flower-tone ($12, Ace Hardware), have a higher level of phosphorus, which is the nutrient that promotes flower formation. Phosphorus is the middle number in the N-P-K nutrient label.

A slow-release fertilizer is packaged into tiny pellets that break down over a period of time, supplying nutrients over weeks or months. This product just needs to be sprinkled onto the soil around the base of your plants, then watered lightly. As always, follow the package directions so that you use the correct amount.

When to Fertilize Endless Summer Hydrangea

In general, as soon as your hydrangea bushes start growing again after the winter, it's time to fertilize. "Just like you and I thrive with a shot of caffeine to wake us up in the morning, Endless Summer hydrangeas bloom best with an early spring application of fertilizer," McEnaney says. Fertilize your plants when you see green foliage begin to emerge from the bases of the stems. If your growing region experiences long, cold winters, expect to see green leaves in mid spring, after the soil warms up a bit.

Buy It: Endless Summer Hydrangea ($37, The Home Depot)

Fertilize Again in Midsummer

After your hydrangeas first bloom in late spring or early summer, you can push them to send up a second bloom with another dose of fertilizer. Wait until the first set of flowers begins to fade, then follow the package instructions to apply more of the same slow-release bloom-boosting fertilizer you used in the spring. Make way for the new flowers by snipping off the faded blossoms, pruning away each flower head down to the first set of leaves.

How to Change the Colors of Endless Summer Hydrangeas

Like other bigleaf hydrangeas, Endless Summer varieties can bloom in shades of blue or pink, depending on the pH of your soil. Fertilizer alone doesn't affect the soil pH enough to change the flower color from blue to pink or from pink to blue, but a couple of commonly available soil amendments can do the job. You'll need garden lime ($6, Lowe's) to raise the pH enough to turn the flowers pink, and a soil acidifier ($12, The Home Depot) to lower the pH and turn your hydrangeas blue.