Indoor plants Hydrangea
Description
Characteristic Features of Hydrangeas
Hydrangea is a genus of deciduous and evergreen plants in the family Hydrangeaceae. However, some botanists are of the opinion that they should be placed to the saxifrage family Saxifragaceae. The genus consists of seven or eight dozen species (some sources say only about 35). Most of them are shrubs 1-3 metres tall or small trees. Others are lianas climbing up vertical supports such as trees and reaching up to 30 metres tall. In the wild, Hydrangeas are indigenous to North and South Americas, South and East Asia. The greatest diversity of species is recorded in the East Asia (China, Korea, Taiwan, Japan, the Philippines, the Russian Far East, and Sakhalin Island).
Sometimes, the plants belonging to the close genus Schizophragma are miscategorized as Hydrangeas, for example, Hydrangea petiolaris and Schizophragma hydrangeoides.
A common name for the Hydrangea genus is Hortensia. Which do you think comes first, the female name or the name of the genus? Historically, the genus was named in honour of a noble woman in the Holy Roman Empire (a European country that existed from 962 to 1806 A.D.).
Of all the numerous Hydrangea species, only one is used for indoor growing, Hydrangea macrophylla, or Hydrangea hortensis that was brought to Europe from China over 200 years ago. Its domestication began around 1790, and breeding started around 1900s. The first variety of this genus (Nydrangea macrophylla var. Japonica) came to Europe, of course, from Japan in 1920. In its habitat in the subtropics, it grows 4 metres tall and is not frost resistant. In the Old World, it became an ancestor of many varieties and cultivars suitable for cultivation in the open ground. However, these cultivars are сonsiderably lower, up to 3 metres (Kyushu, Unique) or even 1-2 metres (Maculata, Matilda, and Tricolour). Indoor cultivars that originate from the same variety are also compact, growing to the maximum of 1.5 metres. In addition, they bloom only once in their lifetime. You can extend their life of your potted Hydrangea for a few years, but it is very difficult to make it rebloom. Fancy trying to refute this pessimistic view?
Hydrangea flowers are produced from the spring to late autumn. They grow in flowerheads at the ends of the stems and reach 16-20 centimetres across or more. The colours are very often white but can also be pink, blue, red, or even purple, depending on the soil. In the acidic soil (pH = 3.0-5.0) the flowers are blue, in slightly acidic (pH = 5.0-6.0) or alkaline soil they are pink. Hydrangea is one of the few plants that accumulate aluminium from the soil. Aluminium will cause the plant produce flowers in the shades of blue. Feed your Hydrangea with an alum solution (3-5 g per litre of water) once every 2 weeks before budding. You can use ammonium AlNH4 (SO4)2, sodium NaAl (SO4)2 or potassium KAl (SO4)2 alum. The latter is easier to find because it is widely used as a leavening agent in baking as well as in other applications (water treatment, leather tanning, and manufacture of fire-resistant fabrics). Please note that you need a pink Hydrangea to do it. White Hydrangea cannot be changed to blue even if you use alum.
The Secrets to Successfully Growing Hydrangeas
Hydrangea prefers bright filtered light and needs some protection from direct sunlight, if it is placed in the southern exposure window. In the summer, move the pot to the balcony or garden because Hydrangeas love fresh air. Hydrangea does not tolerate heat (the flowering period gets shorter and flowerheads fade), so find a place in the dappled light, in the shade of other plants.
Hydrangeas need lots of water. The soil should always be moist! If you fail to water regularly, the leaves will droop. If the air in the room is dry, mist the plant regularly.
The best temperature range is 18 to 25 ° C in the summer and 8 to 12 ° C in the winter.
Regardless of whether you decide to experiment with alum or not, fertilize Hydrangea every two weeks using azalea-specific fertilizer.
By the way, the experiment can be intensified by increasing the concentration of potassium alum solution to 5-10 grams per litre of water and feed the experimental plant two times a week instead of once every two weeks. Then, perhaps, Hydrangea will develop blue flowers even in the neutral soil. As mentioned above, start applying alum before budding.
If you do not want to discard your Hydrangea after flowering, you can do the following:
- Allow the plant to have a resting period by reducing watering in the autumn, limiting fertilization to once a month, and placing the pot in a cool dark place (or basement) for the winter. Do not worry if the plant drops leaves.
- Alternatively, instead of the resting period provide supplementary lighting in the autumn and winter.
In the spring (around March), put the plant in a light place and keep at the temperature of 13-15 ° C. Repot Hydrangea into fresh fertile soil prepared from peat, leaf mold, and sand at 2:1:1. Prune the plant and remove all old and weak shoots. Do not cut off young shoots as they may produce new flowers. Increase watering gradually; when the leaves are fully open, start watering thoroughly.
Hydrangea is propagated by cuttings from young basal shoots (that are not blooming). Root cuttings with two or three pairs of leaves in a mixture of peat and sand for 15-20 days.
Potential Problems
Hydrangea often develops chlorosis, i.e. yellowing of leaves between the veins caused by decreased chlorophyll production in the leaves and decreased photosynthesis. Add iron chelate. (Without going too deep in inorganic chemistry, chelate is a complex salt that helps a living body absorb essential minerals.)
If whitish spots develop on the green leaves, the reason is excessive exposure to light.
If the leaf tips wither and then leaves wilt and drop, the reason is too dry air and underwatering.
If Hydrangea grows poorly and does not blossom, it does not have enough light and feeding.
Control typical fungal diseases (powdery mildew and grey mold) by using fungicides and carefully removing the diseased parts.
Hydrangeas can be plagued by spidermites, aphids, and stem nematodes. Stem nematodes are tiny white filamentous worms 1-1.5 millimetres long and 0.04 millimetres thick. They can only be seen in high magnification so it is easier to detect indirect signs like swelling on stems. Use appropriate insecticides to control the pests.
