Dyeing hydrangeas blue: instructions & tips

Which fertilizer is suitable for blue hydrangeas? How to dye hydrangea blue and keep the color? Our tips on how to properly handle blue-colored hydrangeas.

peasant hydrangeas (Hydrangea macrophylla) are something special in terms of their flower color, because this depends not only on the hydrangea variety, but also on the soil conditions. garden hydrangeas and plate hydrangeas the kind H. macrophylla, which are summarized under the name farmer's hydrangea, bloom in pink, red, violet, white or blue. But blue and purple hydrangeas quickly lose their flamboyant color and turn red or pink - we explain how you can avoid this.

In the following, we show the conditions under which hydrangeas bloom blue and what the soil conditions have to do with it. You will also find instructions on how to dye your hydrangeas blue yourself.

What Makes Pink Hydrangeas Blue?

The reason for the color change in hydrangea flowers of pink and red varieties is due to the flower pigments of the plant. The red or blue dye is called delphinidin and belongs to the anthocyanin group. This color molecule changes its structure with the help of metal ions (aluminium, iron) and forms so-called chelate complexes. These cause an intense blue coloring of the hydrangea blossoms.
In order to turn a hydrangea blue, the flower must first ideally be pink. If their color is too red, the combination with blue delphinidin results in a violet hue. Since white hydrangeas contain no delphinidin at all, you cannot change their color to blue.

Requirements for dyeing hydrangeas blue:

Hydrangeas need acidic soil. This is characterized by a pH below 6. Hydrangeas preferably have a pH of around 4.5, they are well adapted to these acidic soil conditions. If the pH value is too high (> 4.5), the iron and Aluminum ions are no longer readily available in the soil and their uptake by the hydrangea roots highly limited.

Another prerequisite for successful blue dyeing is that the plant to be dyed is the right species of hydrangea. In addition to white varieties of the species H. macrophylla let others Hydrangea Species how velvet hydrangeas (Hydrangea aspera ssp. sargentiana), climbing hydrangeas (Hydrangea petiolaris) and panicle hydrangeas (Hydrangea parniculata) also do not color blue. This shade can only peasant hydrangeas with purple and pink flower color.

Furthermore, the hydrangea must be healthy and sufficiently supplied with nutrients and water. To ensure a needs-based supply of nutrients, hydrangeas should be given a suitable fertilizer every year, such as ours Plantura hydrangea fertilizer be fertilized.

How to test the pH for blue hydrangeas

An acidic soil (soil pH < 5) is one of the basic requirements for blue hydrangea flowers. How to Test Your Soil's pH:

• Put about 100 g of your soil in a mason jar.
• Add 100 ml (distilled) water and mix everything thoroughly.
• After 10 minutes, you can dip a pH test strip into the solution and read the result on a color scale (the pH paper is available, for example, in DIY stores or in pharmacies).
• However, the result determined in this way is not exact: the actual pH value is about 0.5 points lower than indicated.
• You can get a more accurate and faster measurement result with a special measuring device, a so-called soil pH meter.

If your pH reading is above 5, you should acidify it as described later in the article.
The lower the pH value, the clearer the blue coloration of the hydrangea becomes:

• Slightly acidic soil (pH around 5.5): the blue color no longer develops and the blue or purple hydrangeas turn pink or red again.
• Strongly acidic soil (pH around 4): the blue hydrangeas will keep their blue colour, pink hydrangeas will turn blue.

Dyeing hydrangeas blue: instructions and the right fertilizer

In order to achieve the color change of the hydrangea blossoms from pink to the popular hydrangea blue, two main steps are important. The first thing to do is to acidify the soil in which the hydrangea grows. A low pH is the prerequisite for the absorption of aluminum and iron ions, which can be supplied secondarily by adding alum dissolved in water. Finally, maintaining acidic soil pH is important to avoid re-staining.

How to turn pink hydrangeas blue

1. In order to achieve a lowering of the pH value directly during planting, you can either use special (in the Use (usually peat) hydrangea or rhododendron soil or your garden soil directly with peat Mix. Since hydrangeas and other ericaceous plants can no longer efficiently absorb the essential iron if the pH value is too high, this measure is necessary anyway to Iron deficiency in hydrangeas to prevent The acidic pH makes the aluminum in the soil available and the hydrangeas turn blue.
2. In order to achieve a faster and more intense color change in the hydrangea flowers, you can also artificially add aluminum to the soil. More precisely, potassium aluminum sulphate (alum) or aluminum sulphate is used. These aluminum compounds are even available in pharmacies.
   To produce a blue color from the start, water the hydrangea during the growing season sprouting, or until the beginning of June, with a solution of three to four grams of alum in one Litre water. You should repeat this about four to five times at intervals of 7 days.
3. You can get "Blue Hydrangeas" from specialist garden shops. These agents temporarily lower the pH value and turn the hydrangeas blue due to the aluminum. Unfortunately, "Blue Hydrangea" does not keep the flowers permanently blue, but acidifying the soil has a lasting effect. Please do not confuse the hydrangea blue with blue grain. Blue grain is a universal fertilizer that got its name from its own color.

Tip: When fertilizing with alum, always use rainwater or tap water acidified with peat to prevent the pH from raising via the hard, chalky tap water.

Are there home remedies to turn hydrangeas blue?

If you want to do without it, you should rather use environmentally harmful peat and hydrangea blue or alum who can also try using home remedies to turn the hydrangea blossoms blue to evoke. Grape pomace (a by-product of wine production), the needles of conifers or acidic primary rock flour (basalt, granite) are suitable for lowering the pH value of the soil. Iron and aluminum ions are present in sufficient quantities in most natural soils and do not need to be added. For potted plants, a good amount of garden soil should therefore be mixed in to introduce iron and aluminium. Incidentally, an exception here is the acidic moor soil, which is found on former, drained moor areas - this is very poor in iron.

How to keep hydrangeas blue

Choosing the right substrate is particularly important when planting or transplanting blue hydrangeas. The pH value of the soil must then be kept permanently low in order to avoid re-discoloration. One of the ways you get acidic soil with a pH of 4.5 is by watering only use low-lime rainwater that has been acidified by peat, vinegar or bark mulch will.

In addition, you should regularly mulch with leaf compost, lawn clippings or pine litter, as the organic material releases acids into the soil that lower the pH value. The regular use of grape pomace and sour rock dust also helps to keep the soil acidic.
With a soil pH meter you can check the pH of the substrate in order to be able to react in time to an increase in pH.

Tip: If you do not want other plants in the bed to be disturbed by the low pH value, you can also grow your blue hydrangeas in tubs. There it is easier to keep the soil acidic anyway due to the smaller soil volume. Alternatively, it is advisable to create a "bog bed" in which only acid-tolerant plants grow. These include species such as the beautiful berry (Gaultheria procombens) or the lavender heather (Pieris japonica) as well as numerous grasses and the beautiful skimmie (Skimmia japonica).

Summary Dyeing hydrangeas blue:

Two conditions must be met for your hydrangeas to turn beautiful blue:

• Only pink or red hydrangeas of the species Hydrangea macrophylla can be blue or dye dark purple.
• The soil must be acidic, i.e. the pH value must be around 4.5 and kept low: To do this, regularly mulch with acidic material and water with acidified rainwater.
• The blue coloring is easier to achieve in the tub than in the garden soil due to the smaller volume of soil.
• Aluminum ions must be available in the substrate: the hydrangeas can do this with aluminum sulphate be poured (alum solution or special fertilizer), but aluminum is usually found in natural soil in front.

In addition to the right pH value, there are other factors that ensure that hydrangeas bloom magnificently. Everything you need to know Hydrangea care find out in this article.