HomeThere are several more or less easily cultivated species and hybrids of orchids that can be kept and maintained healthy in conditions such as those in a Scandinavian home. Growing orchids doesn't have to be that hard!
- When to give water to an orchid?
A rule of thumb, if unsure about whether to give water or not, is simply to
abstain from giving water. Too much water is worse than somewhat too little.
Many orchids surely want the root system drying up between the waterings. A
good method to find out if there's water in the pot or not, is to lift it up
and feel it's weight. A heavy pot indicates that the medium still holds water
and moist. If the pot is light, surely the potting material is dry. Make use
of transparent plastic pots. If you are able to see through the pot you can
actually see if there's condensed water inside. If there is, don't water your
plant.
-How to give water to an orchid?
Quickly submerse the pot into the water. Remove it from the wet and let it drip
off. There's no more to it than that. A good technique is to scoop up water
with the pot and let the water flow through the potting material.
It's the sphagnum moss that is supposed to suck up water. And it does so readily! If the pot is let standing in the wet too long, all the pieces of bark or coconut fibre will get wet and probably decay at a faster rate.
Monopodial orchids (growing in a rosette) are a bit creaky. The rosette (the joint of the leaves) must not be left wet as it could lead to rot. In nature, orchids grow hanging upside-down from tree-stems and branches. The much better air circulation and higher air temperatures are important factors influencing the evaporation of water in situ.
Most orchids require a height relative humidity. In your home you can raise the RH somewhat, in a few different ways. e.g. spray with a spraybottle on plant parts (n.b. only a short period of higher humidity), use a humidifier or why not place your plants on leca or stones in a container with water. The relative humidity should preferably reach 40% RH on the window sill; many orchids thrive in RH-values between 60 and 85%. If there is a need for such high RH-values, one can put the plants in an orchidarium (a wardian case) similar to a terrarium or aquarium. The circulation of air is very important in orchidariums. Smaller fans can be used to get the air in movement.
Image A terrarium with orchids (Orchidarium). Humidity, temperature and light are kept constant and high
Shrewd bark, sphagnum moss and coconut fibres are commonly used in orchid media. It's important that there can be a circulation of air through the pot (i.e. roots must be ventilated and let to dry up). The plant must not be let standing wet for longer periods of time. The medium needs to be replaced once in a while, as it's slowly decomposed.
Many factors determine when to repot. It's always good to use a bit of common sense.; ... does the orchid look like it's trying to escape the pot? (large specimen of orchids may very well be kept in small pots), .. is the compost 'fresh'? ... does the compost look or feel tired or bad? ... does the orchid look okay?
In nature, many orchids feed on very small amounts of nutrients. The nutrients are dissolved as it rains and reaches the plant sporadically. Orchids are amazingly well-adapted to be able to quickly suck up and store nutrients and water. They manage this with unique roots and highly specialised plant structures such as pseudobulbs and succulent leafs (read more on this).
Orchid-composts that contain bark, fibres, and such things does not supply the plant with nutrients. In semi-hydro-culture, the material used as potting-medium is more or less inert and doesn't contain nutrients either. Everything the plant will need to grow and feel happy must somehow be supplied by you. (As always, there are a few exceptions; there are growers that make use of fresh horse manure and similar media for their plants. Such media contain loads of nutrients.)
Of course, there are a large variety of nutrient salts (plant foods). They vary in 'shape' (liquid or powder?) and chemical composition. Micronutrients should be part of a well-formulated plant food'. The nitrogen sources (N) should preferably be nitrates. Ammonium is a slow nutrient and should be avoided (max 25% of the total nitrogen).
The need for nutrients is specific for every single orchid. Optimal composition of the nutrients differ between species. As the orchid is actively growing, a lot of nitrogen is needed. At resting stages there isn't really a need for more nutrients (all species doesn't have a resting period).
Generally:
Some growers and enthusiasts spend a lot of time on putting together the right nutrients at right concentrations and systematically feed their plants. The ideal is to offer everything the plants need to feel great and to make them perform at their best (flowering etc.). A simple recommendation is to use a well-balanced commercial plant nutrient, e.g. NPK 20-20-20 (with magnesium (Mg) added.).
Too much of nutrients may lead to a precipitate of certain salts onto the roots and into the compost. Roots can be severely damaged by such salts. If there are signs of burned roots or even visible crystals of salt, see to it that the root-system of the plant is well-rinsed with water (as pure as possible). The advice is to lower the feeding portions.
Plants that are 'ill' shouldn't be fed at all.
If you give water to your orchids by 'soaking' the pot (with compost and all) in water you probably use some kind of large container, keeping the water. The plant food is simply dissolved into this water. Orchids that are mounted and sprayed may be given nutrients with the spraying-water (n.b. use low concentrations of plant food, never the recommended (25% is well enough)). Once in a while, take the opportunity to rinse off salts from the roots of the mounted orchids with fresh and pure water without nutrients added. If mounted orchids are sprayed every day, dip them once every, or every second week, or so.
... more about nutrients. The uptake depends highly on the roots.
The water quality is important for all organisms and may highly influence the health of your orchid. It's a fact that orchids grown in pure water (e.g. in RO- or distilled water) produce longer leaves and larger flowers.
Sometimes one hear people talking about the conductivity of the water. This is something that could be used as a measure for nutrient concentrations (as it actually measures the amount of free ions that are dissolved in the water). A water with low conductivity has a lower concentration of dissolved salts than a water with higher conductivity. Rain water, distilled water, and RO-water are examples of 'waters' with a low conductivity.
The conductivity of rain water differs, as it directly depends on circumstances such as pollutions in the atmosphere and similar factors. In the southern parts of Sweden, the rain water has a conductivity of approx. 3-4 mS/m. In the northern parts of Sweden, the values of conductivity are halved.
Lower concentrations of dissolved salts means that the buffer-capacity of the water decreases (there might not be a buffer-capacity at all). When water with extremely low buffert capacity is used to prepare solutions of fertilisers, the pH can decrease to far too low values. At lower pH-values, some salts (more or less micronutrients) might be difficult and even impossible for plants to absorb. One can however add a bit of buffer capacity to pure RO or distilled water, simply by using regular tap water (ca.10%) as a small part of the solution.
Epiphytes generally grow better at pH-values that are somewhat acidic (pH 5,5-6,5) whereas many terrestrials (ex. Paphiopedilum, Phragmipedium) require a higher pH (7,0-7,5).
Even though you're not in the business of growing orchids from scratch you'll might find yourself in the situation of owning a flak of seedlings or mericlones that need to be deflasked.
They're often grown enough to be released when the leaves are a few centimetres long. However, there is a chance that the medium dries up or that something else happens, leading to the two options; take the babies out or let them fall in oblivion.
If there still is medium left in the container dissolve it with some lukewarm water. If necessary, crush the bottle (without hurting the small plants). Use a fine compost of bark-shreds, coconut fibres, or finely chopped sphagnum-moss, to plant the small ones in. The plants can be sprayed or dipped in a weak dose of fungicide or similar (don't use anything too toxic though - better give it a rest).
It's important to never let the small plants dry out. They need to slowly acclimatise from the environment they were used to, the humid flask, to a new, dryer world. Cover them up with some kind of soft plastic sheet (a plastic bag or similar) to increase the humidity and prevent draught. Take notice not to burn the plants. They are not used to that very high intensities of light (never ever put fragile plant in direct sunlight, even dried flowers are effected negatively by such conditions).
To grow plants, you will need good lighting. The light is a requirement for the photosynthesis. Commercial growers and many specialists and enthusiasts use metal halide-lights. There are 'grow light'-fluorescent tubes that are supposed to be good for home usage. The tricky thing with all the different lights is the light! Light isn't just light. Light is composed of various colours (wavelengths of the light-radiation) and only certain colours will do for the photosynthesis (especially important when one wants the optimal light output to be as close to the total effect of the light source).
The fluorescent tubes are sold at better prices than the metal halide-lamps. Suitable photoperiod (light hours) is about 18h per 24h-day.
Place your plants as close to the windows you dare if no other light source (artificial) is used. The intensity of the light drastically decrease the further away from the light source one gets. There are large differences between light in your home and light out in nature.
Windows to the east are often good places to have orchids standing. Southern windows tend to let in too much light and heat from the sun. Orchids shouldn't be put in unprotected sunlight as they might burn. During summer, the orchids are taken outside (not Phalaenopsis and similar humidity and warmth lovers though). Let the 'orchs' swing in the apple-tree! (suitable orchids are e.g. Cambria hybrids, Dendrobiums.)
An orchid receiving enough light commonly has a brighter green colour than an orchid growing too dark. A plant that grows good and flowers well probably gets enough light. Too much light isn’t good either. Leaves may turn yellow and be burned by excessive light. (The sun and some artificial light sources produce light which warms up the plants. Dark spots may appear on leaves that are dehydrating and that are stressed in high intensities of light.)
'Low energy lights' are good light sources for orchids as they can be put fairly close to plants and thus give a lot of light intensity at relatively low heat. They do also radiate a fairly good light-spectrum.
The difference between night- and day temperatures can be substantial in nature. To imitate the difference, a decrease in temperature by 5-10°C during nights, can be applied. Generally, production of flowers is 'started' or induced by a temperature fluctuating period. Different orchids naturally live in different temperatures. It's always best to find facts about the orchid and draw conclusions from that. Reasoning is important when growing orchids. (Remember that the altitude (height above sea) of the habitat is important. Some tropical orchids requires lower temperatures to live well). At higher altitudes, there are probably larger temperature differences, day to night. The microclimate is also very important to recognise when trying to imitate mother nature.
Most of the orchids have a period of rest and a period of growth. Some more or less slows down the growing process during the 'resting' period. It's important that orchids at rest have stored nutrients and water (to live of during the resting). They have specific storing organs, pseudobulbs, for this purpose. Orchids that do have a characteristic resting period should not be fed and sometimes not even be given water during the period. In general terms, orchids that have somewhat of a rest (meaning: applies to pretty much all orchids), shouldn't be fed, and if they are, they should only be fed with weak doses of fertiliser (growing plants do still need some nutrients).
Many orchids take the opportunity to flower during the resting period (which, by the way, often occurres during the winter).
Copyrights © Reserved Markus Axelsson, 2005.
Arditti J. (1992) Fundamentals of Orchid Biology Wiley, cop. New York
Yin-Tung Wang (1995) Effects of six fertilizers on vegetative growth and flowering of phalaenopsis orchids. Scientia Horticulturae 65(1996) 191-197