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How to Grow Hydrangeas

■Types of Hydrangeas

　

  The Japanese hydrangea is classified into three major systems (the Ezo-hydrangea in Tohoku and Hokkaido area, the mountain hydrangea from Kanto to Kyushu area, and the Hydrangea macrophylla in Boso and Izu area in Japan). There are about 20 kinds of hydrangeas in Japan and 400 to 500 species in the Western. Due to the recent evolution of the breeding technology, the number of breeds is increasing and there are more than 1000 of them.

Hydrangea macrophylla is native to Japan and has a calyx that surrounds it. The round blooms are called Temari Hydrangea or Round Hydrangea. These are phylogenetic Hydrangea.These are also called Hama Hydrangea and there are many kinds. They were imported to Europe from Japan around the 18th century, which became the origin of the Western hydrangea, and then imported back to Japan. The color of the hydrangea is mainly pale blue-violet.

There are different ways to grow Japanese and Western hydrangeas, or even different colors, and it's important to grow them to match.

Japanese hydrangea prefers slightly damp and semi-shaded areas with shade and less dry conditions.
Western hydrangeas are better in sunny, well-drained
 areas with a building or plantings to the north where they are less susceptible to winter frost damage. They may also suffer from leaf scalding and poor growth in the summer when the sun is directly in the west and it is hot and dry.

■Planting

 Plant in February or March and November or December. Dig larger planting holes and deepen them with a mixture of compost or humus. Deeper holes are better in dry, good sites. Transplant or divide plants in early November when leaves are falling, or early March before they sprout.

■Fertilizer

　 Fertilize the plant in June or July or during the post-flowering growing season by spreading 1 to 2 handfuls (of chicken manure:oil cake at a rate of 3:2) per plant around the roots or mixing it into the soil. You don't need to use a chemical fertilizer, if you use it, a handful of 1:1:1 mixture of thysso : phosphate : potassium (We call the product "8-8-8"). It is better not to apply too much fertilizer as the branches will grow long, but sometimes cold fertilizer can be applied from December to February and a small amount of additional fertilizer from April to May.

For blue flowers, choose an acidic fertilizer mixing 3g of dissolved phosphorus per litre of soil with 2 to 3g of slow-release chemical fertilizer.
For red flowers, apply more phosphoric acid and magnesium lime than blue flower's.

■Plant diseases and insect pests

　Hydrangeas are not prone to pests and diseases. The pest may be able to get spider mites when it dries out. In summer, spray 1000x Kereisen emulsion depending on the situation. Diseases include leaf spotting, ring spotting, rust, anthracnose and leaf rot. Udon powdery mildew is caused by a fungus, which tends to occur during the hot and humid rainy season, and it is difficult to treat during this period, so chemicals are sprayed to prevent its spread. A winter-to-spring application of chemicals for the following year will help suppress disease. Examples of chemicals include Daconil, Daicenil, Topsin M, Orthocide, and Sulfur Petroxide, which should be applied 2 to 3 times every two weeks. If the disease is present, try spraying Rizorex or Paridazine for crescentic blight control.

■Pruning

  In a sunny spot, It takes shape when left alone. Hydrangeas bloom at the tops of their shoots each year. The new shoots and the second to fourth shoots on this year's flowering branches become flower buds in September or October. Therefore, even if the flowers are trimmed in July after flowering (from the second lower node upwards), they will still flower the following year. This is able to be also a shape pruning.
Crowded or weak branches can be trimmed around January or February. If you want to reduce the size of the whole plant or change its shape, you can give up flowering for a year and prune hard around March or April.

■Way of increasing

 Hydrangeas can be divided and cuttings can be taken. You can divide the plants in mid-February to March and November to December. Cuttings are made in June or early July, using the two sections of the year's branches.

You can put them directly into the soil if you can keep the humidity, but they need growing in the shade. In the case of a planter, any kind of soil (even river sand) will do, but don't add fertilizer at the beginning, and shade and moisture are important for about a month when they take root.

You should not take out the cuttings once you put them up. (Don't pull them out to see if they have taken root! Don't touch it for one winter.) It is important that you do not touch it. If the leaves die, but the buds grow larger, you've succeeded.

■To get a good color

 For blue flowers, an acidic soil is best, a mixture of 5 red ball soil: 3 peat moss: 3 peat moss: 1 humus: 1 vermiculite. (Peat moss is unadjusted for acidity.)
For red flowers, an alkaline soil is best, a mixture of 5 red briquettes to 4 humus to 1 vermiculite with about 30ml of lime per liter added.

Each of these fertilizers can be found in DIY stores (blue and red). (400g/box is about 500-700yen) In the case of potted plants (20cm), you can use about a spoonful (20g).