How & When To Fertilize Hydrangeas in Ohio (Zone 6)

Hydrangeas are beautiful flowering plants that are vibrant in color. Just like other flowers, they bloom best when they are properly cared for. Common hydrangeas grown in Ohio include:

  • Climbing hydrangeas
  • Oakleaf hydrangeas
  • Smooth hydrangeas
  • Panicle hydrangeas
  • Bigleaf hydrangeas

As with any living thing, hydrangeas need food to thrive.


Fertilizing your hydrangeas is an important aspect of caring for these beautiful flowers, but you might not need to fertilize if the soil is rich. By taking a soil test, you can find out if you’ll be needing fertilizers for your hydrangeas. Click here to learn how to make your soil healthy. 

If your soil is already rich in nutrients, there is a risk of over-feeding your plants. The result of over-feeding your plants is even much more detrimental than when your plants are under-fed. Over-fertilization could result in ‘Fertilizer burn’, leaving you with burnt roots and scotched-looking flowers. This is more fatal because there are fewer chances of plants surviving. Over-fertilized hydrangeas will most likely wilt and die.

Note that pale or shabby-looking flowers or leaves are not indications that your plant needs fertilizers. Click here to read: Problem Solving Hydrangeas. 


You could get specially formulated fertilizers for your hydrangeas but there are also general fertilizers for shrubs and trees that are also equally great for every type of hydrangea plant.

The slow-release chemical fertilizer is the least stressful means and it releases a balanced fertilizer once a year. The fast-release chemical fertilizer is also great and costs less than the slow-release fertilizers.

Organic fertilizers are also suitable for your plant as they aid the movement of water into the soil but they may not be very effective during the cold winters of Ohio as the plant nutrients in them will be more slowly released. 

There are fertilizer mixes that are great for hydrangeas but you should seek professional advice if you intend to apply these mixes. Consider bloom booster fertilizers to encourage hydrangea flowering. 

Make sure to read the directions on any fertilizer before using them.


  • Bigleaf hydrangeas need several light fertilizer applications in March, May, and June.
  • Oakleaf and Panicle hydrangeas should be fertilized twice; in April and in June.
  • Smooth Hydrangeas should be fertilized once in late winter.

Generally, you should fertilize your hydrangeas in Spring just when it begins to leaf out to give it an early-season boost. Fertilize them a second time during the growing season of July. The fast-release fertilizers require application twice in summer.

When is it too late to fertilize hydrangeas? 

Stop feeding your hydrangeas two months before the frost date. (October 16th for Zone 6 Ohio) 

Late fertilization will only encourage new and tender flower growths that might not withstand the very cold Ohio winter. These new buds will let in cold into the branches of the plant through the foliage and increase the chances of hydrangeas withering and dying during winter.


Spread the fertilizer along the drip line of the branches. Do not apply chemical fertilizers to the trunk or stem of your hydrangeas. You could apply compost around the base of your hydrangeas to nourish the soil. For the slow-release fertilizer cover it lightly with soil. Fertilizers can be worked a few inches into the soil. Read more

After you fertilize, water! You could also time your fertilizer application just before the spring rain. Watering will ensure that the fertilizer is well washed into the soil and available for the roots of your plants.

Hydrangeas are beautiful flowers and when properly cared for can make the perfect landscape setting. Knowing how and when to fertilize them helps to encourage their growth and keep them colorful, vibrant, and in great shape all season.

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