Skip to Content

Are Eggshells Good For Hydrangeas?

Eggshells are commonly used to maximize efficiency in various applications, particularly in gardening. This is crucial for ornamental plants, which require regular fertilization to enhance their appearance.

Hydrangeas benefit from eggshells due to their calcium content, which strengthens the plant and promotes growth. As eggshells decompose, they gradually reduce soil acidity, inhibiting hydrangeas from absorbing aluminum. Consequently, this leads to the development of purple flowers on hydrangeas.

Proper use of eggshells for hydrangeas

To effectively use eggshells in gardening, it’s important to process them into a fine powder. Large eggshell pieces may not decompose easily over time. Grinding them to a powder increases the surface area, allowing for quicker decomposition in soil.

This is because large eggshell pieces require a higher soil acidity to break down, which is uncommon in typical garden soils. However, eggshell powder can decompose effectively in soils with relatively lower acidity levels.

Make a powder

To create this powder, start by collecting at least ten eggshells. Wash them thoroughly in clean water and allow them to dry. Next, bake the eggshells in an oven set to 212°F (100°C) for 1-2 minutes to eliminate pathogens like salmonella. Be cautious not to overbake, as this can lead to burning and reduce effectiveness.

After baking, grind the eggshells into a fine powder using a blender, coffee grinder, or mortar and pestle. The finer the powder, the better it will dissolve and improve the soil.

Spring is the ideal time to apply eggshell powder to your garden, particularly for hydrangeas, as they are actively growing and require nutrients for new shoots. Distribute 3-7 oz (100-200 g) of the powder evenly around each bush. This quantity is sufficient for the plant’s needs.

Annual application of this eggshell powder is adequate for healthy plant growth. Avoid applying it in summer or autumn when hydrangeas are not actively growing, as it would be less beneficial and a waste of resources.

Read also: Proper Care of Hydrangea

Composting with eggshells

Another effective use for eggshells in gardening is incorporating them into compost. As mentioned earlier, it’s important to first bake and grind the eggshells into a fine powder. This preparation ensures they decompose efficiently within the compost.

When creating compost, it’s advantageous to start with shredded branches from young trees as the base. These branches are rich in nutrients that are beneficial for plants. Following this, add the prepared eggshell powder to the compost, ensuring that its quantity does not exceed 5% of the total compost mass. Mix everything thoroughly to ensure even distribution.

Allow the compost to sit and decompose for a year. Here it is important that each layer of compost has access to air. The decomposition process will slightly acidify the compost, aiding in the dissolution of the eggshell powder. The end result is a high-quality, organic fertilizer that is particularly suitable for nourishing hydrangeas.

Does eggshells affect the color of hydrangeas?

Eggshell powder can indeed affect soil pH, though its impact is contingent on the initial acidity of the soil. The calcium in eggshells dissolves effectively only in sufficiently acidic environments.

When a significant amount of eggshell powder is added to acidic soil, it can neutralize the pH of the soil causing hydrangeas to turn purple. However, once the soil pH reaches around 6.8, the eggshell powder ceases to influence the soil’s acidity further.

Gardeners often manipulate soil acidity to achieve specific flower colors. By adding eggshell powder to the soil, you essentially neutralize it, leading to purple-colored hydrangea flowers. In contrast, if you aim for blue hydrangeas, avoid using eggshells, as their addition will decrease the soil acidity, causing the hydrangeas to lose their blue hue.

For pink hydrangea flowers, the soil needs to be alkaline. Since eggshell powder only neutralizes soil without making it alkaline, you would need to apply garden lime to achieve pink flowers.

It is important to note that the change in soil acidity is a gradual process that takes about a year, about the same amount of time it takes for the subsequent change in flower color. Patience and consistent plant care are essential during this period.

Use fertilizer along with eggshells

Incorporating eggshell powder into your soil is beneficial, but it’s not a substitute for regular fertilization of hydrangeas. These plants require substantial nutrients for vibrant and abundant flowering.

Compost stands out as an excellent fertilizer choice for hydrangeas. Beyond providing organic nutrition, compost helps in retaining soil moisture and protects the soil from rapid drying. Additionally, it shields the soil from excessive sun exposure, preventing overheating during summer months.

For optimal results, I recommend using a slow-release mineral fertilizer alongside organic compost. The market offers a variety of fertilizers with diverse NPK (Nitrogen, Phosphorus, Potassium) ratios.

For hydrangeas, opt for a fertilizer with a higher phosphorus content compared to nitrogen and potassium. Phosphorus plays a crucial role in flower development, ensuring your hydrangeas produce plentiful and attractive blooms.

What you should avoid

There are certain practices involving eggshells that are commonly misconceived and should be avoided for effective gardening.

One such belief is that soaking eggshells in water increases its calcium content, and using this water for plants will yield positive results. However, this is not the case. The process of soaking eggshells in water hardly alters the water’s mineral composition, and the amount of calcium released is negligible, making this effort fruitless.

Similarly, boiling eggshells in water is also based on a myth. This method does not significantly enrich the water with calcium or other beneficial minerals for plants.

Another ineffective method is creating a solution by dissolving eggshell powder in water and spraying it onto hydrangea leaves. This approach does not yield any benefits, as the leaves are incapable of absorbing calcium in this form. The only result is leaves coated with a white powdery residue.