How to care for Orchids
By Keith Kent
How to care for Orchids in the home or greenhouse, article from the orchid grower with cultural advice from watering to feeding!
Here is general orchid information for the majority of genera and should get you on your way to successfully growing orchids without getting too technical or too basic for some . You will find lots of information on this subject in books and the internet, this is mainly my view and what I have learnt since I first purchased an orchid. The hobby is a progression and no two growers are the same this is why it is sometimes difficult to find a straight answer, and can be frustrating for a newcomer to the hobby. Hopefully you will find this article full of straight answers and of good use.
Orchids form the largest family of plants known to science and because of this we as growers can find a orchid to suit most conditions. And this is what is the best option for you to try and achieve, find out what conditions you have in your growing area or greenhouse and then find orchids that will suit those conditions. This way you will have the best chance of being good at growing these intriguing plants. This is very easy in theory in reality though we have all been there and spotted the orchid that we just have got to have.
We get the orchid home and find the spot that fits in to your growing area without a lot of thought to the orchid. I think for most this is a learning process that ignites the hobby to come, all I can say is it is addictive!
Orchids are perennial plants found growing in a wide variety of situations with different growth habits including the large group which are terrestrials which grow in or near the surface of the ground. The other main group of plants are epiphytes, the name derived from ‘epi’(above or on), and ’phyte’ (plant), hence epiphyte: a plant growing on another plant. This group are not parasites which is a myth as they don’t draw food from their host, but only obtain anchorage. They draw moisture and food from the air and from humus collected in angles of trees or crevices. Sometimes epiphytes are found growing on rocks when they are termed as lithophytes.
Orchids are mainly grown in three minimum night temperature zones this being cool 10c (50f), intermediate 13c (55f) and warm 15.5c (60f). It has long been stated that a 10c temperature difference between day and night be achieved, even though I agree with this I differ from most on this on how to reach the difference. I set my required minimum temperature on my heater thermostat and let solar gain do the rest, but you grow in the UK I can hear you say! All I can say is I don’t artificially raise the daytime temperature and get enough heat gain throughout the year to grow and flower my orchids very well. There are spells in a UK winter when it is difficult as you can get long spells of cloud which limit the heat gain to pretty much nothing, this is when you have to watch the watering or spraying and on the odd occasion I may turn the thermostat up whilst I am tending the orchids. I grow at minimum temperatures of 10c and 5c so this obviously helps, damping down and fogging is stopped from Autumn.
There are factors that determine how successful you will be at growing orchids and these are Temperature, Light, Water, Feed, Humidity, Air circulation, potting mix and pest control.
We have mentioned temperature so lets talk about light, most orchids prefer bright diffused light and not direct sun which will certainly heat the leaf surface too much and cause leaf scorch. In winter full light is beneficial but shading will be required in summer to keep the temperatures down, thus reducing the risk of leaf scorch. If growing in the home this can simply be moving the plant more into the room away from the light source, or moving the plant to a different location north/east facing window for example.
I think water quality is important, that much so I only use reverse osmosis water that is almost as pure as you can get but this requires a lot more understanding before you can even think about this route. So for now rain water would be more desirable as long as it is not polluted and from a clean source. Tap water can also be used but I wouldn’t use it straight from the tap, it is best to let it stand and get to the ambient temperature of the growing area, or you could use a mixture of the two. A frequent question is how much do I water? Well it should be how frequent do I water as you can almost give orchids as much water as you like at anyone time without harm. The harm will come if you do this every day or two or to frequently! One of the best ways is to lift the pot and feel how light it is, if it is still heavy then obviously watering can be withheld, if light then we have the opposite so it is probably time to water. You can also check drainage holes, gently insert finger into the potting mix, leave a wooden skewer inserted into the mixture and simply remove to check for moisture on the skewer. Doing this you will learn when to water so as a grower you simply just know when the time is right!
I have a saying ‘If in doubt leave watering out ‘ you are more likely to kill orchids by over watering than under watering. Over watering will rot the roots then the plant is unable to take in water which leads to dehydration and shrivelled leaves which gives the appearance that the plant needs water. So you give more water exasperating the problem which will lead to death of the orchid.
You will see lots of differing views on feeding orchids and there are many feeds available, I would recommend a feed that contains all the main elements of N-P-K, with P being the lowest ratio so 4-1-4 for example with trace elements including Calcium and magnesium especially if you choose to use rain water as rain water is lacking these important elements. Some Calcium and Magnesium is available in tap water so not as much as a issue if you choose tap water.
I measure the ph of the water after I have mixed my feed to water and aim for 6.0-6.2 for most plants, this is important if using rain water as rain water can be too acidic causing elements of the feed to be unavailable to the plants causing deficiencies. Again this is not as much as a issue if using tap water as the feed and water usually buffer each other, it is still a good idea to test ph otherwise you could be too much either way causing problems. Feed strength is important too and can be tested with a conductivity pen, strength can be altered to suit your plants but I would recommend feeding around 550 us/m at every watering or ¼ strength of the recommended dosage of a standard feed .
Orchids like good humidity ideally between 60%-80% but it will fluctuate below and above at certain times of the day and depending on your conditions. If growing in the home gravel trays don’t provide any real humidity benefit but will prevent water drips from spoiling your home so is a good idea, just don’t let your orchid sit in the water this will rot the roots. In the greenhouse you can damp down the floor, benches or purchase a fogger which will omit a mist in to the atmosphere or in both situations misting the plants is beneficial as long as it is not done late at night or in the heat of the day.
Good air circulation is important as it prevents the air from becoming stagnant which can lead to fungal, bacterial and rotting problems, it also prevents dead spots so provides a more even temperature. I like to be able to see the leaves of my plants moving in the breeze, my circulation fans are running 24/7.
Potting mix is another area that you will find 1001 answers to, so actually again there is no correct answer as many will have success with many mixes. However as a starting point I don’t think you can go far wrong with a mix of bark, sphagnum moss and perlite to a ratio of 3-1-1 and choose a size of bark to suit your plant, so for example for Masdevallias I would choose a fine bark, Cymbidiums a medium or large bark. A general rule is the thicker the roots then the larger the bark. If you start with this mix then you can fine tune it to suit your growing conditions so you might add more sphagnum moss if the mix dries too soon or more bark and less moss/perlite if it stays too wet. Or once you gain more confidence may choose a complete potting material altogether.
I now only use CHC ( coconut husk chips ) and am really happy with the results, I would just say if using CHC you are almost learning how to water all over again, I suppose this goes for any change in potting mix so keep this in mind .
I use CHC, sphagnum moss or bark mixes for my sales plants.
Pests, we all hate them and I believe prevention is better than cure so inspect your plants on a regular basis. Orchids are no different to other plants so will attract the usual suspects like slugs/snails, mealy bugs, scale, red & false spidermites, aphids, caterpillars, thrips & weevils. It helps to clean the leaves of your plants if you have the time as this not only makes them look good but will remove any unwanted pests you cannot see with the naked eye. So treat yourself to a eye magnifying glass to really inspect your plants !. Inspect your plants at night, as this is the time most pests will be active and can be easily removed.
I use Provado Ultimate bug killer, a organic oil based bug killer to recommendations with good effect, slug pellets in small numbers and a lot of prevention! I alternate between treatments to hopefully prevent the pests building up a resistance.
Hopefully you have found something in this article of use and be able to put it in to practice with good effect for better orchid growing.