Hydrangea Fertilizer: Tips On Feeding Your Hydrangea Plants

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Hydrangeas make a great addition to the garden or landscape with their large, long-lasting abundant flowers and rich foliage. 

They are easy to care for, but many gardeners find themselves in a quandary when it comes to fertilizing and finding the right fertilizer for hydrangeas.

Colorful Hydrangeas need the right fertilizerPin

As with many plants, less is more; very often, fertilizer is not necessary. If your plant displays yellowing leaves in its center after blooming commences, it’s a sign the plant needs a bit of food.

While there are variations in methods for feeding hydrangea plants, one of the simplest choices is to apply a time-released, balanced fertilizer early in the spring and again early in the autumn.  

Tips For Fertilizing Your Hydrangea

Hydrangea Feeding Q&A

1. Is it alright to fertilize only once a year?

If you just want to fertilize once, early in the springtime, pick a slow-release fertilizer or organic plant food that is intended for use with trees and shrubs.

It’s also best to avoid fertilizing your hydrangea plants in late summer and early fall, as the new shoots produced will be prone to frost damage.

2. Is it necessary to use a fertilizer formulated especially for hydrangeas?

Hydrangeas are not particularly fussy about their food. You can choose an organic or chemical-type all-purpose fertilizer. Look for N-P-K ratios 12-4-8 or 10-10-10 ratio.

3. Is it alright to use rose fertilizer on hydrangeas?

Any fertilizer that is designed for woody plants is a good choice for hydrangeas, and rose fertilizer that is slow-release and has a balanced N-P-K ratio is ideal for annual springtime use. 

Supplement this with doses of liquid seaweed or fish emulsion during the plants’ bloom time for an extra boost of nourishment.

Related: Pruning or Deadheading Hydrangeas For More Blooms

4. Why are fish emulsion and liquid seaweed good for hydrangeas?

These weak fertilizers are a natural source of iron, so if you use these, you do not need liquid iron. In addition to iron, liquid seaweed, and fish emulsion provide an added boost of minerals.

5. Why would Hydrangeas need extra iron?

Iron helps prevent and treat chlorosis. If you notice your Hydrangea leaves turning yellow, you can try giving your plants a light dose of liquid iron

Doing this twice during the growing season can be a nice boost to help keep the foliage strong and green.

6. What is the best natural hydrangea food?

A combination of equal parts peat moss, compost, and sulfur worked into the moist soil surrounding your hydrangea bushes once early in spring and again at bloom time is a welcome organic plant food addition.

7. How much chemical fertilizer is safe?

The amount of chemical fertilizer you use is determined by the size, age, and location of the plant.

Hydrangeas in containers to best with a weekly/weakly application of liquid fertilizer.

A very small plant in the landscape may use an eighth or a quarter of a cup of liquid or all-purpose, slow-release fertilizer carefully applied to avoid root burn.

A large hydrangea bush may do well with two or three cups of granular fertilizer spread over the ground at the branches’ drip line.

8. How do you know how much fertilizer to use?

Always follow the instructions included in the package of fertilizer carefully. If in doubt, remember that less is more. 

Hydrangeas are not especially hungry plants; you can do much more harm by over-fertilizing than by under-fertilizing. A half dose will almost always be more than plenty. 

9. What happens if you over-fertilize hydrangeas?

If you give your plants too much fertilizer or don’t water the fertilizer into the soil thoroughly, you run the risk of fertilizer burning to the plants’ roots. This will manifest as scorched-looking leaves.

10. How can you avoid fertilizer burn?

When using chemical fertilizers, do not allow the fertilizer to touch the plant directly. Keep the soil moist and work it into the soil and water it thoroughly to dilute it and ensure the shot of chemical fertilizer is evenly distributed throughout the soil.

To completely avoid fertilizer burn, use natural fertilizers, such as well-aged compost and mulch.

11. Is it alright to use a fast-release chemical fertilizer on hydrangeas?

You can apply a light dressing of fast-release fertilizer very early in the springtime, again in late spring, and once in mid-summer if you wish. 

Take care to keep this product away from the base of the plant. Apply it under the branches’ drip line. Remember to water immediately and thoroughly after application.

12. When should you stop fertilizing hydrangeas?

Your last application of fertilizer should be in mid-summer (July). This will allow the plant to wind down for the shorter, cooler days of autumn and its winter rest period.

13. How can hydrangeas survive without fertilizer?

Like all plants, hydrangea flowers need more nourishment when they are getting established. Once a plant is mature and settled, it can usually get all the nourishment it needs from good soil and mulch. 

If you have good quality soil or potting mix and amend it with natural organic matter (e.g., compost or aged manure) in springtime, it should provide ample nourishment to your hydrangea bushes.

14. How does mulch help feed hydrangeas?

As the natural mulch decomposes, it releases nutrients into the soil. Adding a layer of mulch late in the autumn helps protect the plant’s roots during the cold winter months. 

Turn it into the soil in the springtime and add more organic matter to keep your hydrangeas happy.

15. Can you make a hydrangea grow or bloom by adding fertilizer?

Fertilizers make a hydrangea grow and produce beautiful blooms as long as they provide all the necessary nutrients.

It’s also much smarter to think of chemical fertilizers as a reward for healthy growth rather than a way to force growth. When you see new growth starting, it’s time to provide fertilizer.

Related: How To Make Hydrangeas Bloom?

16. Will fertilizer help a sickly hydrangea?

If your plant is wilted or sick, don’t fertilize. Applying fertilizer will only cause more stress to a plant that is having root problems or is diseased. In this case, determine what is wrong with the plant and treat it accordingly.

17. What is the best fertilizer treatment for color-changing hydrangeas?

For Mountain Hydrangeas and Bigleaf Hydrangeas, apply a fertilizer formulated for acid-loving plants first thing in the springtime. Look for a product with an N-P-K ratio of 12-4-8 to encourage blue Hydrangeas.

18. What is the best fertilizer for non-color-changing hydrangeas?

Generally speaking, most hydrangeas will do well with an all-purpose dry fertilizer incorporated into the first 2” or 3” inches of soil early in the springtime or late winter. Be sure to water the product immediately and thoroughly after application.

Related: Why is My Hydrangea Turning Brown?

Fertilizer, Hydrangeas, And Color Change

Some hydrangeas will change their flower color in response to pH levels in the soil and water. To determine whether/how your Hydrangea blooms might change colors, identify your hydrangeas and get an accurate read on soil pH levels. 

Test your soil and water to determine exactly what pH levels your hydrangeas currently experience.

Hydrangea fertilizer bag brand name and product infoPin

In addition to water pH, another variable that may affect your soils’ pH levels is proximity to concrete structures such as sidewalks and foundations. Lime leached from these structures will raise soil pH levels.

Hydrangeas that produce white flowers will not change color at all, no matter what. If you have Hydrangea Macrophylla (Bigleaf) or Hydrangea serrata (Mountain Hydrangea), you can encourage the plants to produce blue blooms by adjusting the acidic soil pH level to less than 5.5.

Good soil amendment choices include:

  • Wettable Sulfur
  • Aluminum Sulfate

Be sure to follow the directions on the packaging because excessive amounts of aluminum sulfate will hurt your plants.

Follow up by adding a mulch of pine bark or peat moss. This process will allow the plants to uptake more additional aluminum sulfate from the soil, and this is what causes blue coloration.

This process may not produce all blue Hydrangeas. You may have a mixture of pink and blue blooms on one plant, or you may get purple blooms!

If you want pink flowers, raise the pH level to neutral (5.5-6.5). Alkaline soil conditions produce pinkish flowers. Do this by adding limestone to the soil. 

Follow packaging directions carefully because excessive amounts of limestone will cause your plants to be unable to uptake iron, leading to chlorosis.

Mix & Match To Feed Your Hydrangeas Perfectly

It’s easy to see that there are many ways to feed hydrangeas successfully. The methods you choose will depend upon the types of hydrangea plants you have, soil conditions, soil health, climate, the location of your plants, and several other variables.

These easy-care plants are happy with chemical or organic fertilizers. Generally speaking, just keeping your soil well-amended with compost and manure and protecting the plants’ roots with mulch may be all the fertilizing you need. 

If it seems that your plants need a boost, adding occasional treatments with high-quality chemical fertilizers to ongoing natural, organic nourishment is alright.

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