Oncidium macranthum ( Oncidium Orchid )

Characteristics

Cultivar:	n/a
Family:	Orchidaceae
Size:	Height: 0 ft. to 3 ft. Width: 0 ft. to 2 ft.
Plant Category:	orchids,
Plant Characteristics:	high maintenance,
Foliage Characteristics:	evergreen,
Foliage Color:	green,
Flower Characteristics:	showy, unusual,
Flower Color:	yellows,
Tolerances:

Requirements

Bloomtime Range:	Early Summer to Late Summer
USDA Hardiness Zone:	11 to 11
AHS Heat Zone:	Not defined for this plant
Light Range:	Part Sun to Full Sun
pH Range:	5.5 to 6.5
Soil Range:	Bark to Bark
Water Range:	Normal to Moist

Plant Care

Fertilizing

How-to : Fertilization for Annuals and Perennials

Annuals and perennials may be fertilized using: 1.water-soluble, quick release fertilizers; 2. temperature controlled slow-release fertilizers; or 3. organic fertilizers such as fish emulsion. Water soluble fertilizers are generally used every two weeks during the growing season or per label instructions. Controlled, slow-release fertilizers are worked into the soil ususally only once during the growing season or per label directions. For organic fertilizers such as fish emulsion, follow label directions as they may vary per product.

Light

Conditions : Filtered Light

For many plants that prefer partially shady conditions, filtered light is ideal. Good planting sites are under a mid to large sized tree that lets some light through their branches or beneath taller plants that will provide some protection.

Conditions : Bright Light for Houseplants

Houseplants requiring bright light should be placed within 2 feet of an eastern or western exposure window or within 2 to 5 feet of a southern exposure window.

Watering

Conditions : Moist

Moist is defined as soil that receives regular watering to a depth of 18 inch deep, does not dry out, but does not have a drainage problem either.

Conditions : Normal Watering for Houseplants

Houseplants that require normal watering should be watered so that soil is completely saturated and excess water runs out the bottom of the pot. Never water just a little bit; this allows mineral salts to build up in the soil. The key to normal watering is to allow the top inch or two of potting soil to dry out between waterings. Check frequently as certain times of the year may dictate that you water more frequently. Also, some plants that require normal watering during the growing season, may require less during the winter months when they are dormant.

Conditions : Indoor Watering

Plant are composed of almost 90% water so it important to supply them with adequate water. Proper watering is essential for good plant health. When there is not enough water, roots will wither and the plant will wilt. When too much water is applied too frequently, roots are deprived of oxygen and diseases occur such as root and stem rots.

The type of plant, plant age, light level, soil type and container size all will impact when a plant needs to be watered. Follow these tips to ensure successful watering:

* The key to watering is frequency. Water well then wait long enough until the plant needs to be re-watered according to its moisture requirements.

* When watering, water well. That is, provide enough water to thoroughly saturate the root ball. With containerized plants, apply enough water to allow water to flow through the drainage holes.

* Avoid using cold water especially with houseplants. This can shock tender roots. Fill watering can with tepid water or allow cold water to sit for a while to come to room temperature before watering. This is a good way to allow any harmful chlorine in the water to evaporate before being used.

* Some plants are best irrigated by sub-irrigation, i.e. watering from the bottom up. This avoids splashing water on the leaves of sensitive plants. Simply place the pot in a shallow pan filled with tepid water and let the plant sit for 15 minutes to allow the root ball to be thoroughly wet. Take out and allow sufficient drainage.

* Use an unpainted dowel to help you determine when to re-water larger pots. Stick it into the soil ball & wait 5 minutes. The dowel will absorb moisture from the soil and turn a darker color. Pull it out and examine. This will give you an idea of how wet the soil root ball is.

* Roots need oxygen to breath, do not allow plants to sit in a saucer filled with water. This will only promote disease.

Planting

How-to : Preparing Containers

Containers are excellent when used as an ornamental feature, a planting option when there is little or no soil to plant in, or for plants that require a soil type not found in the garden or when soil drainage in the garden is inferior. If growing more than one plant in a container, make sure that all have similar cultural requirements. Choose a container that is deep and large enough to allow root development and growth as well as proportional balance between the fully developed plant and the container. Plant large containers in the place you intend them to stay. All containers should have drainage holes. A mesh screen, broken clay pot pieces(crock) or a paper coffee filter placed over the hole will keep soil from washing out. The potting soil you select should be an appropriate mix for the plants you have chosen. Quality soils (or soil-less medias) absorb moisture readily and evenly when wet. If water runs off soil upon initial wetting, this is an indicator that your soil may not be as good as you think.

Prior to filling a container with soil, wet potting soil in the bag or place in a tub or wheelbarrow so that it is evenly moist. Fill container about halfway full or to a level that will allow plants, when planted, to be just below the rim of the pot. Rootballs should be level with soil line when project is complete. Water well.

How-to : Potting Indoor Plants

Make sure that the plant you have chosen is suitable for the conditions you are able to provide it: that it will have enough light, space, and a temperature it will like. Remember that the area right next to a window will be colder than the rest of the room.

Indoor plants need to be transplanted into a larger container periodically, or they become pot/root-bound and their growth is retarded. Water the plant well before starting, so the soil will hold the root ball together when you remove it from the pot. If you have trouble getting the plant out of the pot, try running a blade around the edge of the pot, and gently whacking the sides to loosen the soil.

Always use fresh soil when transplanting your indoor plant. Fill around the plant gently with soil, being careful not to pack too tightly -- you want air to be able to get to the roots. After the plant is in the new pot, don't fertilize right away... this will encourage the roots to fill in their new home.

The size pot you choose is important too. Select one that is not more than about 1 inch greater in diameter. Remember, many plants prefer being somewhat pot bound. Always start with a clean pot!

How-to : Repotting Orchids

Potting Terrestrial Orchids Good drainage is important. Mix 3 parts fibrous peat, 3 parts coarse grit, 1 part perlite, and 1 part charcoal. Select a pot that will accommodate roots and about 2 years growth, but no more. Make sure that it has a drainage hole. Hold the orchid over the pot so that the crown is just below the rim of the pot. With your other hand, fill pot with moistened soil mix, tamping to firm. There really is no need to add crockery to the bottom of the pot, but you may want to add a small square of wire mesh or other permiable fabric over hole in bottom of pot. Potting Epiphytic Orchids Epiphytes prefer conditions where roots can be exposed, therefore, tight pots and close-contact soil mixes do not work well and will induce rot. Mix 3 parts dust-free, medium-grade bark, 1 part coarse grit or perlite, 1 part charcoal, and 1 part peat moss together, OR use a commercial orchid mix. As with the terrestrial orchid, select a pot that will accommodate roots and about 2 years growth, but no more. Make sure that it has a drainage hole. Even better, select an orchid pot, which has vertical slits down sides. Hold orchid over pot so that crown is just below the rim of the pot. With other hand, fill pot with moistened bark mix, tamping to firm. Some epiphytes do not need to be potted and prefer to grow on a mound or slab of bark. Until roots attach, tie orchid in place with fishing line. Constant humidity is a must. Support Orchids that have long flower stalks will need staking. Staking is best done as stem grows and before buds open. Many growers prefer to insert stake when potting orchid, but it is up to you.

Problems

Pest : Spider Mites

Spider mites are small, 8 legged, spider-like creatures which thrive in hot, dry conditions (like heated houses). Spider mites feed with piercing mouth parts, which cause plants to appear yellow and stippled. Leaf drop and plant death can occur with heavy infestations. Spider mites can multiply quickly, as a female can lay up to 200 eggs in a life span of 30 days. They also produce a web which can cover infested leaves and flowers.

Prevention and Control: Keep weeds down and remove infested plants. Dry air seems to worsen the problem, so make sure plants are regularly watered, especially those preferring high humidity such as tropicals, citrus, or tomatoes. Always check new plants prior to bringing them home from the garden center or nursery. Take advantage of natural enemies such as ladybug larvae. If a miticide is recommended by your local garden center professional or county Cooperative Extension office, read and follow all label directions. Concentrate your efforts on the undersides of the leaves as that is where spider mites generally live.

Diseases : Bulb Rot

Improperly stored bulbs, or bulbs that are too wet in their dormant stage (usually summer), will be susceptible to fungal diseases that cause them to rot. To prevent this, store bulbs properly when out of the ground. Avoid planting bulbs in poorly drained soils. Fusarium bulb rot can be a serious problem which attacks both the growing plant and stored bulb. Usually introduced by an infected bulb, corm, soil, or even tools, the fungus enters the plant through an abrasion in the tissue. This problem is worse in warm climates where temperatures rarely drop into the freezing range and can persist in soil that stays 60 to 70 degrees Farenheit. Prevention and Control: Buy bulbs that are firm, not mushy. Avoid planting new bulbs in areas where the disease has been present. Unfortunately, there is no treatment for Fusarium bulb rot. Remove all infected bulbs and soil in the immediate area.

Pest : Mealybugs

Small, wingless, dull-white, soft-bodied insects that produce a waxy powdery covering. They have piercing/sucking mouth parts that suck the sap out of plant tissue. Mealybugs often look like small pieces of cotton and they tend to congregate where leaves and stems branch. They attack a wide range of plants. The young tend to move around until they find a suitable feeding spot, then they hang out in colonies and feed. Mealybugs can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.

Prevention and Control: Isolate infested plants from those that are not. Consult your local garden center professional or the Cooperative Extension office in your county for a legal insecticide/chemical recommendation. Encourage natural enemies such as lady beetles in the garden to help reduce population levels of mealy bugs.

Pest : Whiteflies

Whiteflies are small, winged insects that look like tiny moths, which attack many types of plants. The flying adult stage prefers the underside of leaves to feed and breed. Whiteflies can multiply quickly as a female can lay up to 500 eggs in a life span of 2 months. If a plant is infested with whiteflies, you will see a cloud of fleeing insects when the plant is disturbed. Whiteflies can weaken a plant, eventually leading to plant death if they are not checked. They can transmit many harmful plant viruses. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.

Possible controls: keep weeds down; use screening in windows to keep them out; remove infested plants away from non-infested plants; use a reflective mulch (aluminum foil) under plants (this repels whiteflies); trap with yellow sticky cards, apply labeled pesticides; encourage natural enemies such as parasitic wasps in the garden; and sometimes a good steady shower of water will wash them off the plant.

Pest : Aphids

Aphids are small, soft-bodied, slow-moving insects that suck fluids from plants. Aphids come in many colors, ranging from green to brown to black, and they may have wings. They attack a wide range of plant species causing stunting, deformed leaves and buds. They can transmit harmful plant viruses with their piercing/sucking mouthparts. Aphids, generally, are merely a nuisance, since it takes many of them to cause serious plant damage. However aphids do produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface growth called sooty mold.

Aphids can increase quickly in numbers and each female can produce up to 250 live nymphs in the course of a month without mating. Aphids often appear when the environment changes - spring & fall. They're often massed at the tips of branches feeding on succulent tissue. Aphids are attracted to the color yellow and will often hitchhike on yellow clothing.

Prevention and Control: Keep weeds to an absolute minimum, especially around desirable plants. On edibles, wash off infected area of plant. Lady bugs and lacewings will feed on aphids in the garden. There are various products - organic and inorganic - that can be used to control aphids. Seek the recommendation of a professional and follow all label procedures to a tee.

Miscellaneous

Glossary : pH

pH, means the potential of Hydrogen, is the measure of alkalinity or acidity. In horticulture, pH refers to the pH of soil. The scale measures from 0, most acid, to 14, most alkaline. Seven is neutral. Most plants prefer a range between 5.5 and about 6.7, an acid range, but there are plenty of other plants that like soil more alkaline, or above 7. A pH of 7 is where the plant can most easily absorb the most nutrients in the soil. Some plants prefer more or less of certain nutrients, and therefore do better at a certain pH.

Glossary : Viruses

Viruses, which are smaller than bacteria, are not living and do not replicate on their own. They must rely on the cellular mechanisms of their hosts to replicate. Because this greatly disrupts the cell's functionality, outward signs of a viral infection result in a plant disease with symptoms such as abnormal or stunted growth, damaged fruit, discolorations or spots.

Prevention and Control: Keep virus carriers such as aphids, leafhoppers, and thrips under control. These plant feeding insects spread viruses. Viruses can also be introduced by infected pollen or through plant openings (as when pruning). Begin by keeping the pathogen out of your garden. New plants should be checked, as well as tools and existing plants. Use only certified seed that is deemed disease-free. Plant only resistant varieties and create a discouraging environment by rotating crops, not planting closely related plants in the same area every year.

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