How To Fertilize Hydrangeas for Bigger & Better Blooms

Hydrangeas are grown for their big luscious leaves, their usefulness in growing in shady areas and mostly, for their big mophead blooms.

Getting bigger and better blooms is the ultimate bonus, easy to accomplish with the right conditions and a little fertilizer.

As a general rule, hydrangeas grow best when fed with a slow-release fertilizer twice a year in spring and early fall. This is for general maintenance, not necessarily to get bigger blooms.

Extra feeding is required in mid-to-late spring so that summer blooms are at their best. The frequency of feeding will be determined by the choice of fertilizer you use.

Fertilizer Choices

Chemical fertilizers vs Organic fertilizers

Synthetic fertilizers, although derived from natural minerals, are often manipulated to make the concentrations required for good plant growth at a fast pace. Prepared in a lab, these formulations are made specifically for the plant’s benefit and not normally to improve the soil structure.

Organic fertilizers are based on the natural degradation of living organisms like plants and animal manures. In manufactured organic fertilizers, the products are also be manipulated by composting, sterilizing, milling and blending so that the final product is easy to use.

This carbon-based product is released to the soil through microbes which makes it more of a soil conditioner than a plant food, but nevertheless has an effect on the growth of plants. Organic fertilizers are not as concentrated as chemical formulations, but are good for general garden health.

Specialized flower fertilizers

There are products on the market specifically formulated for flowering plants like azaleas, rhododendrons, camellias, gardenias, and hydrangeas. These are the best ones to choose for bigger and better blooms.

The ratio of nutrients for these products is typically around 1 part nitrogen (N), 3 parts phosphorous (P) and 2 parts potassium (K). This formula is designed to produce bigger and more colorful blooms. Dissolved in water, it is typically used as a foliar and soil feed to get to the roots, applied every 7-14 days (depending on the product).

These fertilizers are generally used when buds are setting to increase the number of buds and the size of the flowers. Buds set on old wood from mid-summer and into fall. Boosting feeding during this time will help with blooms the following season.

This fertilizer from Jacks Classic is the perfect ratio to apply to your budding hydrangea plants. See the price on Amazon here.

NPK Numbers

A balanced fertilizer contains equal parts nitrogen, phosphorous and potassium. It also includes a range of trace elements, known as micronutrients, that plants require in smaller amounts. These include elements like boron, iron, manganese, zinc and others.

For bigger and better blooms, more phosphorus is essential in the NPK ratio. For example, 10-20-10 has twice the amount of phosphorous as nitrogen and potassium.

The other ingredients, also used in a lower concentration, also have a job to do. Nitrogen is essential for leaf growth and potassium makes stems and roots strong and moves nutrients through the plants. Without these, the nutrient cycle in the plant will break down.

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