Hydrangeas are flowering shrubs with colourful globe-shaped blooms. They are native to Asia and the Americas. They were first cultivated in Japan.
Although they occur in 75 species, your common hydrangeas are more likely to have come from the more common six species; smooth, big leaf, panicle, climbing, oak leaf and mountain.
Hydrangeas differ in both leaves and flowers. Some hydrangeas produce flat or conical blooms while others are rounded. Oak leafs have their leaves lobbed like those of an oak tree. Other hydrangeas have oval leaves.
Types of hydrangeas
Big leaf hydrangeas
H.macrophylla
Botanically known as Hydrangea macrophylla. These are the common types of Hydrangeas.
They are also known as French hydrangeas. They have large leaves and occur in several cultivars but the common ones are mop head (H. macrophylla and lacep (H.macropylla normadis).
The main difference between the Mop head and the lacep hydrangeas is that the mop head has rounded flowerheads while the lacep flower head appear flattened. The mop head flowers tend to last longer -almost six months compared to those of lacep. Besides even though both occur in pink, blue, and sometimes white flowers, the less common lacep tends to attract pollinators and therefore are good for wildlife gardening.
Panicle hydrangeas(H.paniculata)
Panicle Hydrangeas are the easiest to grow of all hydrangeas. Distinguished by their conical flower clusters which are huge football sized blooms, the flowers are hardy and pretty. Panicle hydrangeas change their hues from green to white to lilac to pink in the fall and finally to brown.
Smooth hydrangeas
They are also known as Wild hydrangeas. In cooler areas, smooth hydrangeas are planted as substitutes for the mop head cultivars. Its identity is the flowers clusters. They are giant white, blue, pink or green. The leaves are deep green and heart shaped. The leaves turn yellow in fall. They are fast growing. Due to their spreading nature, they are ideal for erosion control.
Oak leaf Hydrangea
It’s lobed leaves resemble those of the oak trees hence the name. The leaves turn bronze to red to purple or bright red. In summer, oakleaf hydrangeas burst into an elongated, conical clusters of white flowers which later turn into pink or red. Oak leafs prefer shade but will survive hot seasons.
Climbing Hydrangeas (H. petiolaris).
This hydrangea is distinct because it trails through aerial rootlets that cling to surfaces and clings to walls and pergolas. It can be used to aesthetically frame windows creating a romantic façade with its large ,white flattened flowers. Its blooms are similar to those of lacep hydrangeas.
Although a slow grower at first, and takes time to establish, it rapidly takes off and may need to be controlled. You need to prune out crossing branches to prevent bruises occurring from regular rubbing against each other. Such bruises are entry points for diseases.
Mountain Hydrangeas (H.micropylla serrata)
If you live in cold areas, this is the hydrangea to go plant. Their tolerance for cold conditions is attributed to their cold native ranges of Korea and Japan mountain regions. Although their flowers may be small, their saving is the fact that they are constantly in bloom. Like the lacep they have flattened flowers.
How to feed your hydrangeas
The best food for hydrangeas is cow manure. It contains lots of humus like grass and plant leaves. Cow manure is also naturally acidic and does not increase the PH of the soil. It enriches the soil with natural humus.
Fertilizers for hydrangea
There exist in the market commercial fertilizers formulated to meet the nutritional needs of hydrangea plants. You are advised to use organic products fpr long term results.
Avoid this as it makes hydrangea less hardy.
Newly planted hydrangeas should not even be fertilized. Deny them feeding to enable t development of a well branched, well developed root system that enables them to actively search for nutrients. A deep root system is also the best defense against drought conditions.
Fertilizing potted hydrangeas
Potted plants have a limited space for root development. They therefore need regular feeding to meet their nutritional needs. Potted hydrangeas can be served with the same fertilizers like those of Camelia and rhododendron. You can also use nettle manure. Thin this manure with water to a ratio of 1:5 and apply.
Watering hydrangeas
Hydrangea require fertile well drained moist soil. Their leaves are large and thin and therefore they lose moisture very quickly. In the dry season, it is not uncommon to have to water them twice a day.
Hydrangea flower colours
In hydrangeas the colour of the blooms is affected by the amount of aluminum salt in the soil. Most soils contain large quantities of aluminum. However, in alkaline soils, the aluminum is “tied up” chemically and plants cannot use it. When the soil is acidic or neutral-with PH ranging from 6.2 to 7.0, the flowers will be pink. Truly acidic soil with a PH of 4.5 to 6.2 will produce mauve -coloured flowers.
If you want to make your soil more alkali to produce pinker flowers, add limestone to your soil. To get a soil that is more acidic and therefore give you bluer flowers, water the soil with a solution of 1 ounce of iron sulphate to 1 gallon of water and apply it six times at 10-day intervals prior to opening of blooms. Please be aware that the goal is to enhance the colour and not to change. Attempts to change colour say from pink to blue while the plant is in flower will give you a muddied plant with an identified colour.
It should be noted that these changes in flower colour are mostly for the big leaf hydrangeas.
Hydrangeas come into their glory between March and May-and retain the colour for long periods as long as they are given the right conditions; ample indirect sun and a moisture-laden soil.