Successfull cultivation and flowering of orchids on a windowsill is not as complicated as it seems to be. However, it is important to have basic knowledge and to observe a few simple rules. We also recommend to buy a good book about orchids. Hereafter, we want to provide you with a few tips so that you will be successfull in growing orchids on a windowsill.
One important growth factor is room temperature as well as the temperature during the year which is especially important for orchids with a rest period. Often a (significant) fall in temperature together with water reduction will initiate the flowering period.
According to their need for heat, orchids can be differentiated into 3 Groups:
– hot house orchids which like day temperatures of about 20 to 25 degrees
The most common one is Phalaenopsis (moth orchid) but some Lady´s Slippers (you will recognise them by their marbled leafes) and Dendrobium (for example Dendrobium phalaenopsis) like it warm.
– orchids for tempered glass house which like day temperatures of about 15 to 20 degrees
These are often lady´s slippers (often they have green leaves) and many Dendrobium, Oncidien and Cattleya.
– orchids for cold glass house which like day temperatures of about 10 to 15 degrees
Often these plants are Odontoglossum, Coelogyne or other Dendrobium (as for example the well known Dendrobium nobile) and most of Masdevallia. They like it rather cool and humid (humidity).
Night temperatures for all three groups of orchids should fall by 2 to 3 degrees (nocturnal fall).
We can not always say that all plants of one kind prefer the same temperatures. If you cultivate natural kinds of orchids, it is very important to know your plants´ demands. Most (but not all) of the commercially traded hybrids can be cultivated in temperated or warm environnements we are comfortable in.
Especially in fall and winter, light is one of the most limiting growth factors. For blossom developement it is important to have a proper supply of light otherwise buds will get yellow and die. It is very important for your orchids to have a location which is as bright as possible but not in direct sun because in spring after the dark months, sunlight will cause ugly burns. A half-curtain for sun protection will be efficient and can be removed easily when needed (in fall or winter). Windows leading east, west and south (please ensure proper sun protection) are the best choice.
Most orchids like a humidity of 50 to 60 percent, just as we do. Therefore, each orchid room should be equipped with a thermometer/hygrometer to control temperature and humidity. If you want to increase humidity, we recommend an ultrasonic electronic air damper.
Movement of air
In nature you will always find air movement. A slight wind is always blowing but it is very different in a room. Often there is no air circulation which leads to unregular heat distribution especially in winter when all windows are closed. Therefore, during the whole year, a fan is best suited to move and mix the air. We recommend fans from the American based company Vornado. It is sufficient to have them run 15 Minutes per hour (in winter) and 15 Minutes per 90 Minutes (in summer).
In summer, windows are mostly open and provide a proper air change. In winter it is different so please make sure to open windows at least twice a day. This is not only good for the plants but also for you! Please make sure that the plants will not get a cold shock when it is very cold outside. Please put them in a warmer place when you air.
Most commercially traded orchids such as the well known Phalaenopsis are epiphytic orchids. They grow on other plants and have other plants carry them upwards towards the light like in an elevator. In particular it has to be emphasised that these orchids are not parasitic plants such as mistletoe because orchids do not detract nutrients from plants which they grow on. Caused by this way of life, roots of epiphytic orchids are intensly surrounded by light, air and changing humidity. Water (rain water) is very soft and contains very little nutrients and minerals.
For all gardeners this means that most orchids prefer water which is soft and has room temperature. Daily spraying in the morning (so that the plant will be dry again until the evening) increases growth.
Only Lady´s Slippers need more calcium and mostly prefer higher pH numbers. Therefore, water most of the lady´s slippers with soft tab water and ensure a calcium supply by mixing eggshells of your breakfast egg into the compost or smashed seashells into the coaster.
Except for Cymbidium, most orchids are light feeders. Therefore, they only need very little fertiliser and even are salt-sensitive, true to the motto less is more. Please only fertilise during growth period from April to September. Most commercially traded orchid fertilisers contain all important macronutrients, micronutrients and even organic plant excipients such as vitamins.
Sympodial orchids such as Cattleya, Oncidium… can be breeded quite easy by seperation (per section you should at least have three pseudobulbs).
From time to time monopodial orchids such as Phalaenopsis grow little children (layers) which can be seperated from the mother plant when they have two to three roots and are five to six centemeters long. If you leave nothing to change or you even want to start breeding, you will need a laboratory.
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