Which of the following best explains the differences in flower color of the African violet in the greenhouse?

In 1892, Baron Walter von Saint Paul discovered the African violet, Saintpaulia ionantha, in the East African country of Tanzania.  The genus, Saintpaulia, was derived from this explorer’s name.  The specific epithet, ionantha, refers to the violet color of the flowers.  African violets belong to the family Gesneriaceae that also includes popular flowering plants such as Streptocarpus and Gloxinia.  These beautiful flowering plants are no longer just violet colored.  Thanks to their popularity, many hybrids and varieties are now available.  The different flower colors and flower and leaf shapes come from mutations of the original plant.  When a new form is discovered, growers propagate the unusual plant to form a new variety.  It is not uncommon to see pink, white, mauve and bicolor blooms.  In addition, African violets may have single or double blossoms that sit delicately atop their soft velvety leaves.  Standard plants typically grow about 8-12 inches in size, while new miniature varieties stay around 4 inches in width.

Cultivation Information

Light

The general rule is to supply plants with 10-12 hours of strong light each day.  In their natural habitat, African violets are protected by forest tree canopy.  As a result, they need filtered sunlight during the brighter summer months.  During winter months when the sunlight is weaker, plants may benefit from light derived from southern exposure.

Many experts say that artificial light works as well as and more reliably than sunlight.  The best artificial lighting is achieved with a pair of 40-watt florescent lights.  Ideally one should be a cool-white and the other a warm-white daylight tube.  These should be placed approximately 8-12 inches above the plants. If your plant has dark healthy leaves but no blooms, try increasing the light. If it is blooming but has pale leaves, reduce the light.

Temperature & Humidity

African violets are well adapted to indoor environments.  They prefer a temperature between 65°F and 80°F with about 80% humidity.  It is important to avoid temperature and humidity fluctuations, including sudden drafts.  To provide an adequately humid environment, you may want to use a humidifier or place pots in a tray filled with gravel and water. DO NOT mist the foliage.  Water on the foliage may cause permanent leaf spotting.

Watering

Use water that is room temperature. African violets are susceptible to crown rot, so it is important that the crown (the section of the plant at soil level) is not saturated with water. Generally, watering the plant from above is not recommended.

WATERING METHODS

1. Place the pot in a saucer filled with water for 15 to 30 minutes. Water will be absorbed into the soil through the pot’s drain hole. To avoid root rot, DO NOT let the pot sit in water for more than 30 minutes.
2.  Wicking system – When potting an African violet, bury a synthetic cord (natural material will rot) in the soil and fish it out through the drain hole.  The soil absorbs water from the saucer through this wick. Place a layer of gravel in the saucer to keep the soil from being in direct contact with the water in the saucer. The constant water source in the saucer allows the plant to absorb water as needed. This method can aid in overall humidity as well.
3.  Specialty, self-watering pots – These pots consist of a glazed ceramic outer pot and a non-glazed inner pot. The outer pot is filled with water and–after it is inserted in it–the inner pot is able to absorb moisture through its porous walls as needed, similar to the wick method.

Potting & Soil

It is recommended to re-pot African violets once a year to help deliver new nutrients to the plants and remove salt buildup. African violets prefer to be slightly rootbound.  The diameter of the container should measure no more than one-third the width of the plant’s leaf span. A plant with a leaf span of 12 inches, for example, requires a 4” pot.

African violets prefer a light soil mix that allows for good drainage.  An ideal mixture is equal parts of peat, perlite, and vermiculite.  Most general mixes require the addition of dolomite lime to achieve an overall pH balance between 6.0 and 7.0.  Another option is to purchase a mix specially created for African violets from your local garden center.

Fertilizer

Apply liquid fertilizer at half or one quarter strength every time the plant is watered.  Diluting the fertilizer helps to keep delicate roots from being damaged.  Look for a mixture that is equal parts nitrogen (N), phosphorus (P), and potassium (K), such as 20-20-20.  Special mixes for African violets are also available at local garden centers.

Additional Care

Clay pots may accumulate fertilizer salts. When the African violet’s leaves and stems come into contact with these salts, they can burn and eventually rot. The best ways to combat this problem:

• Do not overfertilize.
• Install a waterproof barrier between the leaves and the pot.
• Soak the empty pot in a solution of 1 part vinegar to 3 parts water overnight, then thoroughly rinse.
• Use a glazed ceramic or plastic pot.

Watch for pest problems. Mealy bugs, aphids, and spider mites commonly attack African violets.
LOOK FOR:

• Insects
• White cottony secretions
• Stunted or distorted new growth

If you spot pests on your plants, contact your local university extension office or garden center for advice on an appropriate treatment.

Propagation of New Plants

New African violets can be produced from existing plants.  Cut leaves from the original plant, leaving 1 inch of leaf stalk (petiole) attached to the leaf.  Bury the stalk and up to ¼ inch of the leaf in a wet sand/vermiculite mixture.  Cover lightly with plastic and keep the media moist. Within two to six months, new plantlets will form on the leaf.  Carefully separate these plantlets from each other and plant individually.

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