What’s the Best Fertilizer for Hydrangeas?

Hydrangea plants are one of the best flowering shrubs you can grow in your garden. If you plant them in the right location suited to your hydrangea variety, they’re relatively easy to grow. With careful planning, the reward will be a gorgeous floral arrangement that lasts all summer long.

However, you can’t just forget about your hydrangeas once planted. There’s still a bit of TLC involved, and to get the best blooms, you need fertilizer. So, what’s the best fertilizer for hydrangeas?

Here’s everything you need to know, from the best fertilizers for hydrangeas to some tips and sound advice.

What’s the Best Fertilizer for Hydrangeas to Bloom?

Some novice gardeners assume specialty fertilizers are needed to help their plants thrive. However, hydrangeas aren’t that picky, so you can use a basic fertilizer.

Generally, you can use:

• Organic, slow-release, all-purpose, balanced fertilizers with a 10-10-10 ratio will give the plant an all-round balance of essential nutrients.
• Organic, slow-release fertilizer with a 10-20-10 formula to give your hydrangeas the nutrients they need to produce an abundance of larger flowers. Note that this formula has a higher ratio of phosphorous, the vital nutrient that promotes flower buds. It is ideally applied in late summer to early fall to encourage flowers the following year.

When using a slow-release fertilizer, loosen up a fine layer of the topsoil and mix it together. This will enable the breakdown of the fertilizer granules, activating the nutrients.

There’s a myth that hydrangeas are acid-loving plants. However, an acidic fertilizer can reduce the soil’s pH balance, harming your plant. As a rule of thumb, don’t use acidic fertilizers unless you test the soil’s pH first and find that you need to increase the acidity levels.

Furthermore, some people wonder if they need different fertilizers for different hydrangeas. Generally, this isn’t the case. You can use the same fertilizer for limelight hydrangeas (A.K.A panicle hydrangea) as you would for a mophead, lacecap, and other varieties.

That said, you might want to change the fertilizer to enhance the color of specific blooms.

Fertilizing Hydrangeas to Change the Color

Some hydrangeas change color based on the soil’s acidity. For example, aluminum sulfate enhances the blue tones in blue flower sepals, while garden lime brings out deeper pinks in pink flowers.

This is because sulfur acidifies the soil, increasing the plant’s uptake of aluminum and turning the plant’s petals blue. Meanwhile, lime (calcium carbonate) neutralizes acids in the soil to make a more alkaline flower bed, which can lead to more pink tones.

In other words, the fertilizer you choose can change color depending on the type of hydrangea you have.

Here’s a rough guide to coloration and soil pH:

• Soil pH 5.0 to 5.5: Blue
• Soil pH 6.0 to 6.5: Pink/purple
• Soil pH 5.5 to 6.5: Purple or both blue and pink

It’s best to make these changes gradually so you don’t shock your plant. Plus, you need to time it right–adjust the soil in late fall or early spring, giving the plant plenty of time to adjust before it’s time to bloom. Overall it could take two growing seasons to successively change the color of the blooms. It is also advisable to regularly test the pH of your soil for best results.

Note: White flowered hydrangeas can not be changed to another color.

When To Fertilize Hydrangeas

When you fertilize hydrangeas, it varies depending on how they’re planted. For hydrangeas in the ground, you need to fertilize three times:

1. In early spring, when the plants are just leafing out.
2. In early May, to boost flower production.
3. In late June or early July help finish the summer season with strong and healthy growth.

For hydrangeas planted in containers, there are two options. Newly planted hydrangeas will appreciate a slow-release formula added at planting time and again in late spring. However, check if your potting soil already contains fertilizer– as there’s no need to fertilize twice!

If you overwintered your hydrangeas in containers, add fertilizer in early spring and May. They won’t need fertilizer over the summer.

You might have noticed that we never mentioned fertilizing in the fall. Why, you ask? Betty Montgomery, author of Hydrangeas: How to Grow, Cultivate & Enjoy, explains, “You should never fertilize plants late in the growing season because you want them to go to sleep naturally.”

Nature follows a cycle, and so do your plants. Let them rest when it comes to fall, so you can enjoy gorgeous blooms every summer.

6 Tips for Fertilizing Hydrangeas

For more tips on how to fertilize your hydrangeas, here’s some expert advice from the pros at Gardener’s Yards.

1. Start Fertilizing a Year After Planting

As we mentioned above, you only need to fertilize your hydrangeas in spring and early summer. However, you don’t need to do this until the year after planting. This applies to bigleaf hydrangea, panicle, smooth, oakleaf, and mountain varieties. These are all re-blooming varieties that require extra energy in the summer.

2. Use the Right Amount of Fertilizer

You should always apply fertilizer according to the packet instructions. Apply it on the soil surface beneath the whole spread of the branches, then water the plants well. You should avoid the leaves as some fertilizers can cause leaf burn.

Overfeeding can cause problems. You’ll get lush foliage but fewer blooms. As hydrangeas are beautiful flowering shrubs, you don’t want to risk losing the spectacular floral show they put on each year.

3. Troubleshooting Hydrangea Fertilization

Sometimes, you can experience problems with your hydrangeas. The following are some common issues and how to fix them:

• Healthy leaves but struggling blooms: If the nitrogen levels are too high, your hydrangea may have strong leaves and stems, but at the expense of producing flowers. Reducing nitrogen levels will help.
• Yellowing of leaves: High phosphorous levels can prevent an uptake of iron, resulting in chlorosis and yellowing of leaves. Reduce the phosphorous levels to fix it.
• The plant isn’t blooming or growing: If the potassium levels are too high, the plant won’t be able to take in other nutrients, causing an overall deficiency. Try reducing the potassium.

Sometimes, it may be a case of over-fertilizing. So, if your plants are leafy but not producing a lot of blooms, try giving them a break from fertilizing and skipping a year. Instead, add compost and mulch to the soil to give them time to bounce back.

4. Test Your Soil pH

For the best results,it is recommended to test the pH of your soil. This test step can provide you with a lot of information about what’s happening in the ground, which, otherwise, you’d have no idea about. You can then go on to  develop a more strategic plan of care for your hydrangea..

Some gardeners send soil samples to local labs to learn about the pH and soil nutrients. However, there are easier ways to test the pH. Purchase a pH tester online or at a garden center, which will tell you the essential information you need to know.

As a result, you can tailor your hydrangea’s fertilizer to suit the specific environment.

5. Don’t Overlook Compost

We’ve touched on using compost when taking a break from fertilizing. But did you know that you should add compost to your hydrangeas anyway? Organic compost can provide the soil (and thus, the plant) with essential nutrients.

If you have mainly sandy soil in your garden, composting can also improve the structure of the soil itself. As a result, your plants will benefit.

Add compost once a year. You can either add it around the base of hydrangeas or compost the entire surface of your garden.

6. Water Your Plants

This advice seems obvious–all plants need water! However, you need to water carefully during the fertilizing season as if  the roots are dry, the fertilizer might be too strong and cause chemical burn. You’ll notice symptoms like leaf spot, that appear as dry, brown spots on the leaves.

Generally, hydrangeas need around one inch of water per week. Some will come from rainfall, but  check that they’re getting enough water in general before you fertilize.

Help Your Garden Flourish

If you get your care plan right, hydrangeas can be a rewarding plant to grow. Their colorful blooms will easily outshine their neighboring plants with a magnificent show. All that’s left for you to do is provide the right fertilizer.

Hopefully, this guide has given you an insight on how to correctly fertilize your hydrangeas. Check out our blogs for more information on plant care and gardening tips.

Frequently Asked Questions

Our most frequently asked questions on fertilizing hydrangeas.