Double Crowns (Crown Suckers)

Question:  I have a couple of violets that always seem to get extra sets of leaves growing from the center of the plant.  Eventually, I have to divide these plants when they get bigger but the problem will reappear.  What can I do?

Answer:  Unfortunately, “double crowning” (suckering in the plant center) is a genetic condition that won’t simply go away by removing the additional center growth or dividing plants.  If this has happened more than once with the same plant, it will likely continue to happen.  Stress also is a factor, since plants subjected to more of it are more likely to double crown or sucker.  Excessive heat, light , or neglect in watering or potting can all lead to excessive suckering and double-crowns.  Disbudding can also be a factor, since many plants don’t seem to do this unless grown for show and disbudded.

The only real solution is to not grow these varieties, or at least not to propagate using these plants.  If others grow the same variety without having this problem, you might try to acquire a plant propagated from them.  They may have a different genetic “strain” of that variety that is less likely to double-crown.  We’ve had some older varieties that have developed this problem, and will propagate them, select those plants that grow the best, then propagate only from those, and so on.  If we’re lucky, we can eliminated the problem, given enough time.

Neem Oil for Powdery Mildew

Question:  My sister sent me some “Neem oil” to use for powdery mildew, but I haven’t a clue how to use it.  Could you tell me?

Answer:  “Neem oil” is processed from seeds of the neem tree, native to eastern India and Burma, and is a wonderful product that can be effective as an insecticide, miticide, and fungicide and is safe for home use.  It biodegrades quickly, and exposure to neem oil poses no threat to humans or other higher animals, or to “beneficial” predator insects (only to those who feed on plants).  Though it doesn’t directly kill plant-feeding insects, it does act as an irritant, discouraging them from feeding on the plant.  For this reason, it’s best used regularly as a preventative, or to attack pest problems in their early stages.

We’ve found its best use is as a treatment for powdery mildew, the very fine, white powder that appears on leaves and, sometimes, blossom stems.  Though powdery mildew rarely will kill a plant, it will scar the surface of leaves and lead to short-lived blossoms.  It tends to be a particular problem when there is cool, stagnant, humid air.  Spraying with neem is an easy, immediate, non-toxic solution for dealing with powdery mildew on a large number of plants.  There is minimal damage to open blossoms (a few varieties appear more sensitive), and leaves will look shiny and clean.

We spray with 100% pure neem oil, at a rate of 1 tsp. per quart of water.  To this, add 1/4 tsp. of liquid dish soap, which is need to mix the oil well in the water.  If the oil is very thick, use warm water when mixing.  Spray all plant surfaces generously with a fine mist.  Best of all, it’s not toxic to humans–we don’t use either masks or gloves when using it.  That said, don’t be so careless as to swallow it or spray it into your eyes (not lethal, but not pleasant either).  As for the odor, it smells a lot like sesame oil.  To store neem oil, keep at room temperatures (it thickens if chilled), and shake well before using.

Scarring on Backs of Leaves

Question:  I have brown scarring on the backs of my lower leaves.  Why?

Answer:  This is a question we received by phone.  We didn’t immediately have an answer until he happened to mention that he grew in clay pots, and also wondered why the bottom row of leaves was bent over the pot rims.  The culprits, of course, were the clay pots but, since we hadn’t grown violets in these in nearly 30 years, it didn’t quickly come to mind.  Besides their weight, expense, and difficulty to clean (and keep clean), scarring of the petioles and undersides of leaves can be a problem presented by clay pots.  Being porous, the pot absorbs the water (and whatever is added to it).  The water will evaporated and the pot will dry, but some of the fertilizer remains within the clay, most noticeably on the pot rim–like a ring on a bathtub.  These accumulate over time and can burn, or “scar” the undersides of leaves and their petioles when they come in contact with the pot rim.  This can be more of a problem for African violets, which produce leaves in a flat rosette, than for plants that grow more upright.

A solution for those who prefer to grow violets in clay pots is to create a barrier between the leaves and the pot rim.  One simple solution is to cut thin strips of aluminum foil and fold them over the pot rim.  Using a glue gun, you might also apply a thin bead of glue around the pot rim–or apply a bead of silicone of bath-tub sealant.  Another is to cut thin nylon tubing (like the kind found in tropical fish stores), lengthwise, then secure them to the pot rim.  Some exhibitors use the latter method even with plastic pots, since it helps protect the lower leaves of large showplants from the sharp rims on plastic pots (“rolled”, or rounded, rims are better for this reason).

That said, clay pots are attractive and can make plants look even more so.  Just be aware of their shortcomings and adjust your culture accordingly.  Because they are porous, soil will dry much more quickly than when potted in plastic.  Water is evaporated only from the soil surface with plastic pots, but from soil and pot surface with clay pots.  This means that plants with small root systems, like miniatures, will dry very quickly in clay pots and will need to be watered quite frequently.  Also, very light, porous, soilless mixes that work so well with plastic pots may dry too quickly in clay pots.  A heavier mix that retains more water may work better when using clay pots, unless one plants to keep the plant and soil constantly wet.  Finally, if you want the advantages of plastic pots, but the appearance of clay, you might simply grow in plastic and slip plant and pot into a slightly larger clay pot!

Effect of Too Much Light?

Question:  I grow my violets 15″ below 4-tube fixtures.  The lights are on 12-16 hours a day.  On some plants the center leaves look crowded and a little hard, but I’m not sure if this is due to too much light or not.

Answer:  This may, indeed, be the result of too much light, particularly for most standard-size varieties.  This is particularly true for many varieties with wavy, ruffled, or girl-type leaves that, by their nature, tend to crowd in the center. 

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