Had an orchid growing-related question burning in the back of your mind? This is the section for you – here you can find the wisdom and knowledge of our members presented in a ‘question and answer’ format. If you don’t find your question addressed here, please use the form below to ask our experts!
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Why won’t my orchid bloom?
How do I increase the humidity?
In the home one of the easiest ways is to fill trays or saucers with gravel or pebbles and put water in them. Put the plant ABOVE the water, never in it. Make sure to use a non-porous container like a plate or saucer if you are putting your plants on a wooden surface or a surface that will be damaged by moisture.
Humidi-Trays are an excellent tool to do this. These are plastic trays with a plastic fitted grate (they come in various sizes). They can be set on a window sill or table top. The plants sit above the water that is held in the tray below. The trays hold the water, the grates hold the plants and the evaporation of the water increases the humidity around the plant.
Other ways of increasing humidity around the plants is by using hand sprayers of various designs (handheld or larger compressed sprayers) and periodically mist the plants with water. If you are growing in an outdoors or in a greenhouse you can use a misting system that is either controlled by a timer or by a humidistat.
How much light do I give my orchid?
Phalaenopsis and Paphiopedilum like it about 70-90% shade. For Vandas most Dendrobiums and some others you will need very bright conditions from 30 % shade up to full sun. For Cattleyas and Oncidiums from 50-70% shade.
One way to check your light levels with some confidence is to quantify it by using a light meter to see what will grow best in your situation. Light is measured in foot-candles. There are a number of resources that specify what the light requirements of certain orchids are. JODOS members can help answer these questions at a monthly meeting.
What temperatures do my orchids want?
Cool orchids from the higher mountains like a minimum of 10 degrees C, intermediate orchids from the plateaus like it more like 13 degrees C minimum and warm orchids from the lowlands like it more like 18 degrees C minimum. If you can figure out how to keep your orchids near the temperatures that they need the orchids will be happy.
Cattleyas, Phalaenopsis, Oncidiums, Vandas and most Paphopedilums are considered warm growing and need a range of 15 – 32 degrees C. Other orchids are considered to be cooler growing genera like Cymbidiums, Odontoglossum, Miltonia, Masdevallia and Phragmipedium. Many orchids are adaptable and it is an easy matter to put cool growers a little closer to a window where the temperature will be lower in the winter or a warm grower back from the window where the temperature will be higher. It is a matter of finding the right micro climate in your home or growing situation. If you are comfortable, then the orchids often are too.
How often should I water?
Watering more is appropriate when the light and temperature is higher, or the humidity is lower. Plants in baskets or on mounted on slabs generally need more water. Plants in small pots or in clay pots might also need more water. When there is more air circulation (which orchids love) or if the plants have thinner leaves watering more might be appropriate. Watering less is better when there is less light and the temperature is lower. Or when the humidity is higher.
Plants in plastic pots or larger pots can require less water. Watering less might be more appropriate when there is less air circulation or when the plants have thicker leaves. And it is important to remember that some orchids like certain kinds of Dendrobiums require a rest period where they receive no water at all (typically in winter). Again, it is all about the kind of orchid that you are growing.
What's the best fertilizer to use? How often should I fertilize?
I do change my formulations using a higher Nitrogen fertilizer (for leaf growth) from August to January and a lower Nitrogen, higher potassium fertilizer (to support flowering) from February through May. In general, do not fertilize in the wintertime. As you learn the needs of the kind of orchids that you grow you may want to fine tune your formula depending on your water quality and the potting media you use. The adage is “weakly, weekly”.
That said, it is best to fertilize about once a week or two in the spring and summer and reduce it to about once a month when the weather turns cooler. It is also good to flush out the excess salts from the media about once a month. Use pure water for this flushing.