When it comes to perennial flowering shrubs, the hydrangea is hard to beat! With its huge flowers and bright, colorful foliage, it’s a popular choice among gardeners. For hydrangeas to bloom vigorously and consistently, you need the right care. Both nurturing pruning and the right fertilizer play an important role in keeping garden and potted hydrangeas in full bloom. Knowing when and how to fertilize your hydrangeas can make a big difference in the quality of their bloom cycle and overall quantity of blooms.
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When should you fertilize hydrangeas?
If you’re dreaming of a gorgeous hydrangea bloom, you may be wondering when is the best time to fertilize the ornamental plants. The right time to fertilize depends on the type of hydrangea you have, for one thing, but there are also some care tips that apply to most types of hydrangeas. So that we can briefly answer the question, hydrangeas should be fertilized once or twice a year – definitely in early spring after pruning and if needed just before blooming.
Fertilize hydrangeas in early spring
Fertilizing in early spring helps keep hydrangeas green and ready for the season. This fertilizer needs to be low and slow dosed to evenly supply nutrients to the plant.
This can be done in several ways, either by a vigorous top dressing of fresh compost or by using a good slow release granular NPK fertilizer at the base of the plant.
A thick layer of fresh compost in the spring can provide hydrangeas with the nutrients they need early on. A 4 to 6-inch layer under the plant is sufficient. You can also use a general-purpose mineral fertilizer to fertilize hydrangeas. Both release nutrients slowly into the soil. This slow pace is perfect for even growth, which is also very important to support and spur the coming bloom cycle.
If you use a fertilizer that is too strong or one that doesn’t release its nutrients slowly, it can cause excessive leaf growth. As a result, all the energy goes into leaf growth, leaving little for larger flowers.
Fertilize hydrangeas before flowering
The second time hydrangeas should be fertilized is just before flowering. Here the exact time of flowering depends on the variety you have.
If your hydrangeas bloom in late spring and early summer, you should administer the second dose just before they unfold their flowers. The same applies to hydrangeas that bloom in late summer/early fall – again, you should administer the second dose as soon as they begin to bloom.
The dosage of fertilizer in this case is different from the initial slow and low dosage in the spring. Instead of a fertilizer that contains equal amounts of phosphorus, nitrogen and potassium, you should use a fertilizer with a higher phosphorus content.
Phosphorus is a key element in flowering vigor. Adding phosphorus right at the beginning of the blooming season will increase the overall performance of your hydrangea’s blooming cycle. A ratio of 10-30-20 (nitrogen-phosphorus-potassium) is particularly suitable at this time. This fertilizer will still provide adequate nitrogen and potassium, but the increased phosphorus content will contribute to a larger and more vigorous bloom. When applying the fertilizer, water it well into the soil so it can be absorbed more quickly.
But note: You should not fertilize freshly planted shrubs further during the first year to ensure good root development. You should also stop fertilizing hydrangeas from July onwards, otherwise the new shoots will not lignify until winter and the plant may suffer frost damage.
Mineral or organic fertilizer for hydrangeas?
Whether you feed your hydrangeas with a mineral or an organic fertilizer depends to a large extent on your personal preferences. For long-term fertilization that is as natural as possible, an organic fertilizer is recommended.
Hydrangeas love acidic soil, so well-seasoned cattle manure is the ideal fertilizer for this ornamental plant. It is naturally acidic and will not raise the pH of the soil. The natural fertilizer can still be applied in the fall, as it needs time to release its nutrients.
Natural fertilizer for garden and potted hydrangeas.
If you are avoiding mineral fertilizers in your garden, you can also use some home remedies and garden waste to fertilize your hydrangeas. Here are a few options:
Fertilize hydrangeas with leaf compost: Composted oak leaves can provide hydrangeas with minerals and nitrogen. Starting in March and continuing through the end of August, add a 2-3-inch layer around the plant, working it loosely into the soil and watering well.
Needle compost as hydrangea fertilizer: rotted 2 to 3 year old needles of various conifers provide the plants with numerous nutrients, minerals and plenty of nitrogen. Apply this natural fertilizer every two weeks during the growing season.
Fertilize hydrangeas with coffee grounds: coffee grounds are rich in nitrogen, potassium and magnesium and can still lower the pH of the soil. Sprinkle some around the root zone of your hydrangeas to nourish them.
Horn meal for hydrangeas: Horn meal or horn shavings can also provide nitrogen to hydrangeas. Rake a handful of it into each shrub once a year.
Fertilize hydrangeas in a pot
Like most ornamental plants, hydrangeas have differences in care when you grow them in pots instead of outdoors. Because potted hydrangeas must be overwintered frost-free, they absolutely need a two-part fertilization. If you have chosen an organic fertilizer, the first fertilizing should be done in spring – between March and May, and the second in summer – between June and August. If you use a mineral liquid fertilizer with nitrogen emphasis, you should follow the manufacturer’s recommendation, and stop fertilizing from June.
Fertilize hydrangeas for large flowers
Fertilizing twice in early spring and before your hydrangeas bloom works wonders for great blooms. And with each passing year, the effect becomes even greater as the plant develops lasting vigor.
One of the most important points is that you stay consistent. The more consistently you give your hydrangeas the nourishment they need, the more you will be rewarded with beautiful blooms.