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Growing Healthy Orchids

Cattleya Jungle Flare  - © 2008 Greg Allikas

Lycaste x micheli 'Everglades Amarillo' CHM/AOS grown by Everglades Orchids. Photo © G. Allikas

Healthy orchids are the result of a carefully planned culture regimen in which the plants are observed on a regular basis and grown in a clean environment. Many ailments can be quickly detected and dealt with before they affect other specimens in a collection. A few minutes spent each week checking plants is the best prescription for a clean bill of health.

An effective program begins with the purchase of vigorous orchids. Invest in specimens bearing green leaves devoid of black or yellow marks. The plants should be securely rooted in a mix that is firm, not mushy and acrid.

Isolate new purchases for two weeks before adding them to a collection to prevent any insects or diseases from infecting other orchids. If any ill effects are noticed, take the plant back to the seller and ask for advice, or request a replacement.

Maintain a spotless growing area. Remove faded flowers and dead leaves promptly. Water early enough in the day so the plants and flowers dry by night. Do not let puddles of water accumulate. Operate fans or open windows (during warm weather) to provide adequate ventilation. Fertilize enough, but not too much, or weak growth, which is susceptible to insects and diseases, will result.

When an infection is noticed, act swiftly. Identify the culprit. Take the plant (or a sample leaf or flower) to an orchid society meeting, the nursery where the plant was purchased or a county cooperative extension service. Wrap the sick specimen in a plastic bag to prevent it from infecting plants at the destination. However, do not leave it in an unvented car in the summer, or an unheated car in the winter, or additional injury may result. The ailment will most likely be one of four basic kinds.

Aphids, scale, mealybugs, thrips and spider mites are a few of the insects that attack orchids. The first three are easily seen; the last pair require the aid of a magnifying lens. Talk with local orchid growers to learn how to identify these insects and their symptoms. New growth and buds are common attack points. Understand the insects' life cycles and apply repeated doses of a control to eliminate all phases. Soft, cottony mealybugs on this new paphiopedilum growth will deform the leaves. Prompt action is necessary to eliminate the insects.

Fungi and bacteria injure orchids. A warm and humid environment with inadequate ventilation creates the perfect atmosphere in which fungi and bacteria thrive, causing soft spots, sunken areas on leaves, root rot and other ailments. Inadequate air circulation and damp conditions can induce Botrytis cinera, which ruins flowers with its fine speckling.

Orchids are prone to viruses that can cause flowers to be abnormal. Typical symptoms are streaking of color and deformity of flowers, and irregular light and dark streaks in leaves. When uncertain if a virus is to blame, consult a professional. Businesses exist that will test orchids for the presence or absence of virus. Destroy virus-infected plants; viruses can infect other orchids and cause harm.

Viruses are spread by animal insect vectors, and by improper hygiene, such as ineffective sterilization techniques on recycled pots and clips, and cutting tools. When severing a flower cluster or dividing orchids, always sterilize the cutting tool by passing the blade through a flame or dipping in alcohol. Use disposable gloves on each plant to be divided.

Physiological Disorders
An imbalance of water, light and temperature creates symptoms of problems. For example, overwatering can cause roots to rot, and, because the plant cannot absorb water, the pseudobulbs to shrivel. The effect is noticed on the psuedobulbs, but the cause is in the medium. Frequently, a change in the care program will solve physiological ailments.

Once an insect or disease problem is identified, choose an appropriate solution. Do not reach for the nearest available pesticide. Consider effective options that will not harm the environment. A cluster of aphids on a cattleya shoot can be carefully wiped off with a cloth soaked in sudsy warm water. Dab away mealybugs lodged in a bloom sheath with a cotton swab dipped in alcohol. Diatomaceous earth sprinkled on the medium discourages snails and slugs.

Occasionally it is necessary to rely on a chemical, especially when many plants are involved. Some growers plan regular spray programs to control insects and diseases. Houseplant insect sprays are handy to spot-check a single plant, especially in the home (but remove the plant from the growing area prior to spraying); more elaborate systems may be employed for larger operations.

Before spraying, be forewarned that some chemicals will damage flowers. The oil carrier (usually xylene) in emulsifiable pesticides can injure flowers or plants, often in conjunction with high temperatures.

Frequently repeated applications are necessary to eradicate all traces of an insect. Be prepared to spray two or three times at seven-to 10-day intervals.

Before applying any chemical:

  • Write down the phone number of a physician or a local poison control center.
  • Make sure no people or pets are in the area. Keep them away from the spray site for 24 hours.
  • Move orchids grown indoors to a well-ventilated area.
  • Read the label directions.
  • Make sure the substance is recommended for orchids.
  • Be certain the toxin is the right one for the job.
  • Wear appropriate clothing to protect yourself.
  • Know how to dispose of the unused toxin.
  • Clean yourself thoroughly after applying any toxic substance.
  • Clean the equipment and then store it beyond the reach of curious hands.
  • Make sure the area has been replenished with fresh, clean air before family, friends and pets re-enter the area.

Some orchids benefit from being placed outdoors for the summer. Before their return indoors in the autumn, thoroughly inspect each specimen to prevent any unwanted guests from entering the growing area. Once indoors, populations of aphids, mealybugs, spider mites and other insects increase dramatically in the warm and moist environment. Inspect the container's sides, drain hole, developing buds and all of the foliage, especially the undersides of leaves, where insects often lurk.

Spend the time to understand how orchids grow during each season. Then should a problem arise, it can be dealt with effectively in a way that is safe for the plant, the owner and the environment.