The orchid family (Orchidaceae) is one of the largest plant families on earth with more than 28,000 known species. Orchids can be found on every continent except Antarctica, but it’s the tropical regions of the world that grow the most diverse number of species. They are noted for their uniquely shaped, colorful, and often fragrant flowers.
Most orchids are epiphytes growing on top of other trees, shrubs, or rock outcroppings often holding on using coarse aerial roots. They get water and nutrients from the air, rain, and any organic debris that may pile around them. Other orchid species, especially those grown in temperate climates, are terrestrial. They grow in the soil of grasslands and forests.
Tropical, epiphytic orchids make up the majority of orchids grown and collected as houseplants. Hundreds of species can be cultivated indoors, but a few are much easier to grow indoors and can be easily found at greenhouses and garden centers. The best orchids for home gardeners to grow include:
- Moth Orchid (Phalaenopsis)
- Dancing Lady Orchid (Oncidium)
- Cane Orchid (Dendrobium)
- Corsage Orchid (Cattleya)
- Slipper Orchid (Paphiopedilum)
Care of Orchids
Often orchids seem like hard-to-care-for or delicate plants. The opposite is actually true! The difference is that orchids require different care than typical houseplants.
Light is one of the most important environmental factors to consider because it impacts how the orchid responds to other environmental factors like water or fertilizer. Light is typically one of the most limiting factors for growing orchids indoors. When plants do not have enough light, they are dark green and will not flower. A medium, grassy green color is an indication of adequate light levels. Orchids require bright indirect light, often the same kind of light that African violets (Saintpaulia) prefer. Avoid hot exposures – usually east and south-facing windows are best. If needed, many orchids grow well under artificial light. When artificial light, such as fluorescent or LED lights, are used, select high-output, full-spectrum lights and position them within 6 to 12 inches of the foliage. Most orchids need at least 14 hours of light a day under artificial light.
Soil (aka Media)
Because they are epiphytic, most orchids do not grow in soil. Instead, they are often grown in coarse bark or sphagnum moss, referred to as “media”. Occasionally you will see orchids growing in an expanded clay product (i.e. Aliflor), rockwool, or lava rock, but these growing media are typically used by more advanced growers. The important factor for all of these media types is that they have very sharp drainage to keep the coarse aerial roots healthy.
What is used by the gardener is often personal preference. Coarse bark and sphagnum moss have their benefits and limitations. It is possible to use a mix of both to get a good balance of air and water retention for the species of orchid you are growing and your watering habits.
Bark mixtures are preferred by most gardeners. They are typically made from coarse chips or pieces of fir bark. Its attributes include:
- Excellent drainage
- Dries out quickly and is more forgiving if overwatered
- Breaks down quickly and therefore needs to be replaced frequently
Sphagnum moss mixtures are made with coarse, long-fibered pieces of unmilled sphagnum moss. Its attributes include:
- Much more moisture retention (Often causes issues with over watering and root rot)
- Has very little air space
- Is cheaper and easier to use for most gardeners than bark
- Requires frequent repotting
Some species of orchids are occasionally grown with no media at all and instead are mounted to the surface of a board or on another plant. Not all orchid species are successfully grown this way, but Vanda and Brassavola are two examples that respond well to being mounted.
Many container options are available for orchids and all must have exceptional drainage. Drainage holes are often larger and more numerous both on the bottom and sides as compared to a “regular” garden pot.
Options for orchid containers include:
- Clear plastic pots (allow for roots to photosynthesize too!)
- Plastic pots with raised domes in base
- Net pots – plastic containers reminiscent of a laundry basket
- Wooden baskets
- Terracotta (which is porous to allow for quicker drying)
- Glazed ceramic (looks great, not as porous)
Double pots can work well to disguise ugly plastic pots, just be sure they never hold excess water. Orchids like “cramped quarters”, so a proper-sized container often looks a little too small.
Orchids are often classified into three main groups based on the temperatures they prefer.
- Cool (60-75°F days). Preferred by Cymbidium, Odontoglossum, Miltonias, and some Paphiopedilum and Dendrobium
- Intermediate (70-80°F days). Preferred by Cattleya, Oncidium, some Phalaenopsis, and many Paphiopedilum and Dendrobium.
- Warm (75-85°F days). Preferred by Doritis, many Phalaenopsis, and some Paphiopedilum and Dendrobium.
Most orchids will grow in intermediate temperatures. If you are unsure which group your orchid belongs to, treat them as intermediate. For nearly all orchids, a 10-15°F temperature change from day to night is very important to help with flowering, as well as growth and development. Seasonal variation (difference in overall temps between summer and winter) is important too. This is especially true for flower development. Many gardeners already have seasonal variations in the temperature of their homes, so this is not as difficult to achieve as it may seem. Take advantage of “microclimates” in your home. For example, it is cooler in a spare bedroom or closer to the window, so that is the best location to grow orchids in the cool temperature group. Utilize a thermometer with a min-max reading for a 24-hour period to determine if you are getting the appropriate temperatures throughout the day and year.
Humidity indoors is often exceptionally low – much lower than orchids would prefer – especially in winter. Indoors, it is almost always below the ideal range for orchids which is 40% to 70%.
Methods to raise humidity include:
- Grouping plants – especially with other plants like ferns
- Pebble trays
- Misting is not effective (the droplets are too big!) but misting can be beneficial for watering and cleaning foliage.
A humidity gauge is an important and beneficial tool to help you get this very important environmental factor in the right range.
Unlike other houseplants, air movement is a critical consideration for growing orchids. It is closely linked to humidity. Orchids need high humidity but high humidity without air movement promotes disease issues. Conversely, high air movement can lower relative humidity in the area. A balance must be reached between these two factors. Set up a fan or use a ceiling fan to gently move air around the plants. If leaves are moving a lot, it’s probably too much air movement. Reposition the fan to provide gentle air movement without blowing directly on the plants.
Watering is one of the most critical care considerations for orchids and it looks different from other houseplants. Improper watering is the number one reason people have problems with orchids. There is no “magic” formula to watering because when to water depends on many factors including, plant species, plant size, light, temperature, humidity, media composition, container, the season of the year, and stage of growth. Orchids should be watered just as they dry out – before wilting, but after the media is dry. Those species with pseudobulbs (bulbous-shaped stems at the base of the leaves, like with Oncidium or Cattleya) should be allowed to dry out completely. Those species with no water storage organs (like Phalaenopsis) should be watered just as the media dries.
Many strategies can be used to determine the appropriate time to water. When dry, the media will be lighter in color and the media will weigh less. A wooden chopstick inserted into the coarse media will come out completely dry and can be used as an indication of when to water. The most fool-proof strategy to determine if water is needed is to touch the media with your finger. If it feels dry, water and if it feels wet, don’t water. If you are questioning it, wait one or two more days.
To water, run water over the media until it runs out the bottom of the container. Avoid wetting the foliage. Water with copious amounts of water – much of it will flush away. This assures that all of the media is thoroughly wetted and helps flush out excess salts and fertilizers that may build up over time. Often it is best to water plants, then come back a few minutes later and water again to allow thorough water absorption. Always empty saucers, trays, or outer pots within 30 minutes, and never allow plants to sit in water.
Some sources and hobby orchid growers prefer to water orchids by placing a few ice cubes on top of the media and letting them melt, wetting the bark or sphagnum moss. While nearly all commercial orchid growers and collectors advise against this watering method, one study has shown this form of irrigation to have no adverse effect on growth or flower display length on some species of orchids. All of the same considerations must be considered whether you water with ice cubes or running water. Only water once the media has dried out and never allow the orchid to sit in water for extended periods of time.
The source of water is an important consideration. Nearly all municipal sources of water and well water are fine to use for nearly all orchids. If it is safe to drink, it is typically good to use for orchids. Softened water is not recommended because over time it can lead to salt build-up in the media. Water from a dehumidifier is ok but can lead to a buildup of metals in the media if used extensively over time. Rainwater is best, but not always readily available. Distilled water can be used for sensitive species.
In general, orchids need less fertilizer than most houseplants. Proper nutrition is important for good bloom. Fertilize frequently at a low dose (quarter strength or less). This “weakly weekly” approach to fertilization works well for most orchid species and gardeners. Use a balanced fertilizer like 10-10-10 or 20-20-20 that does not contain urea and has a good mix of micronutrients. Water-soluble fertilizers are often the best and easiest to use. At least once a month, skip fertilizer and flush media thoroughly with plain water to prevent salt build-up. Fertilize only when plants are actively growing in the spring and summer months. If the rooting media is very dry, thoroughly wet it before applying fertilizer.
Pruning and Deadheading Orchids
Orchids will not need extensive pruning. Remove any brown or dead leaves and aerial roots with a sharp pruners or scissors. Sterilize the pruners between plants with a 10% bleach solution to prevent the spread of any diseases or viruses.
Once all the flowers have faded, the flower stalk can be removed. Prune the stalk carefully as close to the base as you can with sharp and sterile pruners, scissors, or a razor blade. When ready to rebloom, the orchid will grow a new flower stalk. The popular moth orchid (Phalaenopsis) is one of only a few species that will occasionally continue flowering on the same flower stalk. For moth orchid, once the final flower has faded, cut the flower stalk off leaving two nodes on the stem. The nodes are the small brown lines located along the lower part of the flower stalk. Healthy plants will initiate new flowers to form at one of those nodes, usually within eight to twelve weeks. While additional flowering is not guaranteed when pruned like this, it is worth a try!
Orchids benefit from repotting every two to three years. The coarse potting media often breaks down allowing it to hold more water and causing root rot issues. Additionally, if the orchid’s root system has become too large for the container, pushing the plant up and out, a new larger container is needed and new potting media should be used when placed in a larger pot.
To repot, start by removing the orchid from the old container. If the plant doesn’t easily slide from the container, try squeezing the outside of the pot to loosen things or run a sharp knife around the inside of the pot. Carefully pull all the old potting media from the root mass. If the roots are dry, soak them in water for a few minutes. Then pull-apart and loosen all the roots cutting out any soft, dead, brown, black, or hollow roots. Rinse off the root system and the inside of the container.
In many cases, the orchid can go back into the same size container. Only move up a size if you cannot physically fit the root mass in the container. The size of the container is determined by the root mass, not the size of the leaves and stems. This may lead to using a container that appears small. Place the plant inside a clean, sterilized container (use a 10% bleach solution), and while holding the plant with one hand gently add the coarse media around the roots. Use a chopstick, dowel, pencil, or another device to get the media between all the coarse roots. Be careful as you firm or push any bark or other media around the base as the coarse roots are easily snapped or broken. Finally, water the newly potted orchid thoroughly.
Moving Orchids Outdoors for Summer
Moving an orchid outdoors for the summer can be one of the best things you can do for your orchids! Do not move plants outdoors until you are guaranteed to have temperatures above 55°F at night. In most parts of Iowa, this is the end of May. Even if grown in bright indoor light, the change in light intensity when moved outside is significant. Transition them to the new, brighter light outdoors gradually by starting them in heavy shade and then gradually over a couple of weeks moving the orchid plants to light shade. Never place plants in full or direct sunlight – it’s just too much light.
Once outdoors, the care of the plants will be similar to their care indoors. The frequency of watering and fertilizing will like increase, especially if they are in a location outdoors that does not receive rainwater. Monitor frequently for pests and diseases. Scale, mealybug, and spider mites (when dry) can all potentially become an issue outside. Frequent and diligent scouting and dealing with the pest before it becomes a large issue is important. Bacterial and fungal diseases are more common with splashing water and higher humidity outside. When you see a disease issue, remove infected leaves with a clean/sterile cutting tool taking one inch of green leaf tissue below the damage – treat cut end with a fungicide.
In late summer or early fall begin monitoring nighttime temperatures. The cooler temperatures in fall can help initiate flowers in many species but once temperatures dip below 50°F at night, the orchids need to come back inside. Clean and sterilize your indoor area before bringing them in. Once indoors, monitor carefully for pests and diseases, including ants and roaches in the substrate, especially for the first two to four weeks.
Getting Orchids to Re-bloom
Some orchids bloom annually, others will bloom continuously. Providing all the proper environmental conditions (light, temperature, water, fertilizer, etc.) will allow for the orchid to bloom well.
There are many factors that may lead to an orchid that fails to re-bloom. Reasons why orchids don’t bloom include:
- One of the primary reasons why orchids do not re-bloom.
- When indoors the best location is usually a south or east window.
- If leaves are dark green, they are not receiving enough light and they are not as likely to bloom well. Instead, orchids should have leaves that are a medium, grassy-green color.
- Move plants to a brighter location or provide supplemental light.
- Orchids that have not been adequately fertilized will not flower well.
- During the active growing period during the spring and summer months, fertilize weakly weekly using a balanced fertilizer.
Improper Day Length
- Some species of orchids require short-day or long-day conditions. Research your species to determine if they require a specific day length.
- Make sure they are not growing in locations where the length they are exposed to light (sunlight or artificial light) is not appropriate for the species.
No Temperature Drop
- Most species need several weeks of a 10-15 degree drop in temperature at night - ideally down to 55-65°F.
- Many also rely on seasonal variation in temperature (warm summers, cool winters) to bloom. Be sure overall, temperatures are cooler for part of the year to trigger flowering. This happens naturally in the fall – which is why so many species bloom over the winter months.
Common Issues of Orchids
Too Much Light
- A common problem when moving them outdoors in the spring
- Plants should be a light green in color. They turn yellow-green or sometimes red in too much light
- Can progress very quickly and will eventually cause white, then brown spots that die
- Provide more shade as quickly as possible when symptoms show up
- Always transition orchids to new light intensities slowly to prevent leaf scald or other problems
- Too much fertilizer can cause brown/dead root and leaf tips, yellowing of leaves, and salt build-up on the container
- Prevent fertilizer burn by watering with plain water, then fertilize after the media has been thoroughly wetted
- Flush media regularly and repot orchid with fresh media regularly to reduce salt/fertilizer build-up
Wrinkled or Leathery Leaves
- Shriveled, misshapen, accordion-folded pleats, limp, and leathery leaves are all symptoms of insufficient water
- Evaluate watering frequency and water more often if plants are dry for too long in between waterings. Do not overwater
- Evaluate the root system and look for green or white, plump roots in growing media that are still coarse and intact. Brown, shriveled roots are an indication of potential root rot. Rooting media that is compacted or broken into smaller pieces is likely holding too much water promoting root rot. Raise humidity and repot the orchid in fresh media
- Common pests that can cause discoloration, distorted growth, and sticky honeydew
- Prevention is important – don’t bring in infested plants and isolate them immediately when you see them
- Control with a good cleaning, soapy water, insecticidal soap, Neem
- Common in dry conditions
- Causes mottled foliage and heavy infestations will have fine silk webbing
- Control by regularly wetting/washing foliage and raising the humidity
Scale and Mealybug
- Very difficult to control, mealy bug is often hiding in the media as well
- Infestations should be dealt with swiftly and quickly when first noticed
- Cleaning (with rubbing alcohol) can be a good start, follow up with several rounds of insecticides such as Neem, horticultural oil, or insecticidal soap
- Persistence is key to control
- Toss heavily infected plants to reduce the potential of infecting other plants
- The moist, well-drained media for orchids is an ideal home for ants
- They don’t cause damage to plants, but are often a sign of another issue (like aphids, scale or mealybug) and are a nuisance
- Control by dealing with primary issue (such as aphids), repotting (and thoroughly washing container and removing the media), or by using baits or traps
- Often live in the media, especially if orchids spend time outside
- Can cause damage to growing points and flower buds, along with being a nuisance and human health hazard.
- Watch carefully for them (they are nocturnal), keep the growing area clean of leaf debris
- Control with repellents, baits, sticky traps, or insecticides
- A decay and collapse of the plant or pseudobulb near the crown
- Almost always because of too much water. Let plants dry out between waterings, change media if it holds too much water
- Phyllosticta Leaf Spot
- Small, elongated black/purple spots (surrounded by tan or gray) along veins of leaves
- Spreads readily in low light and wet conditions
- Be sure plants don’t have leaves that stay wet overnight
- Remove affected leaves to prevent spores from spreading – repeated applications of fungicides can be used
- Black Rot
- Caused by a few different species of fungus
- Moves very quickly through plants and spreads easily by splashing water to other plants
- Avoid wetting leaves and have good air circulation to prevent infections
- Remove all infected parts with sterile knife
- Apply a fungicide to the remaining healthy parts
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on January 7, 2022. The information contained within may not be the most current and accurate depending on when it is accessed.