Wick Watering and Fertilizer Use

Question:  You’ve discussed the “wicking method” for watering plants before.  Besides using a “lighter” soil, should I change how my violets are fertilized?

Answer:  Yes.  Unlike watering from the top, or by saucer, at regular intervals, the soil is nearly always moist when wick watered.  Though a wicked plant won’t require any more nutrients, a greater volume of water passes through the soil, since it never experiences a “dry” period (much of it simply evaporates).  As a result, there is greater danger of fertilizer buildup within the soil. To avoid this, less fertilizer needs to be added to the water when wick-watering.  For plants that we have wicked, we’ve found that using fertilizer at 1/2 the normal dilution was sufficient.  For example, 1/8 tsp. rather than 1/4 tsp. per gallon, the latter dilution being that used when top watering.

Another consideration when selecting a fertilizer to use for wicking is its water solubility.  We’ve found that some powdered fertilizers can accumulate on the wick and clog it, if the wick is ever allowed to dry.  If you experience a similar problem, a balanced, liquid fertilizer may be appropriate

Water Stains on Leaves

Question:  I’m very careful with my watering, not to get any on the foliage of the plant, but many of my violets still show what seem to be stains on their leaves.  These appear mostly on the leaf edges.

Answer:  This is a very common problem, particularly when nights are cool and soil is damp.  What’s happening is that cool nighttime temperatures are causing “dewdrops” to form on your plant’s leaves.  When the “drop” evaporates, it leaves behind a stain.  We find this particularly a problem in the spring and fall, when days are warm and nights are cool, and usually after we’ve watered and the soil is wetter than usual.  The solution, of course, would be to moderate daytime and nighttime temperatures, and to water plants early in the day.  This would let they dry some before temperatures drop at night.  Doing these thins will also help control powdery mildew.

Watering African Violet Species

Question:  I recently purchased a species violet (S. velutina) at a local show, and discovered that it had been wicked.  Can I repot it into my usual soilless mix (and top water) without danger of losing it?

Answer:  Certainly.  If anything, we find that most of the species violets do a bit better if not kept overly moist, and like a vely light, porous soil.  Most grow more compactly than the modern hybrids, and seem to have a smaller root system.  For this reason, we prefer to top water most of our species, and are careful not to use too large a pot.  Most seem happy in 3″ or 4″ pots (grown as houseplants, and not for show).  Having said this, wicking is perfectly acceptable, so long as a very light soil mix, with plenty (50% minimum) or perlite being used.

Fertilizer Formulas and Dosage

Question:  What fertilizer do you use?  I have only been able to locate Miracle Gro for African Violets and it is 7-7-7.  I have found no 15-15-15 or 20-20-20.   Do you have any suggestions?  At this time I am doubling-up on the Miracle Gro.

Answer:  The numbers you are referring to represent the percentage of the three major nutrients; nitrogen, phosphorus, and potassium, respectively, contained in the fertilizer.  In this case, the 15-15-15 fertilizer contains a bit more than twice the relative amounts of these nutrients than does the 7-7-7.  The 20-20-20 fertilizer contains almost three times the relative amounts.  Since all three fertilizers contain the same amounts of nutrients relative to each other (i.e. all are “balanced” formulas), you could double (or triple) the usage of the 7-7-7 fertilizer to achieve the same diet as the others.

That said, you need to ask “double” what?  What unit of measure is being used?  One may call for a quarter teaspoon of dry fertilizer while the other calls for 7-10 “drops”, or a quarter “capful”.  Rather than get a headache trying to figure all of this out, its best just to follow the instructions on the label for whatever fertilizer you choose to use–the manufacturer has already done all of this math for you.  Most fertilizers will give directions for every-watering use (what we’d suggest), or for occasional (2-4 weeks) use.  Use whatever dilutions apply for your watering and feeding schedule.  If you use constant-watering systems, such as “wicking” or “self-watering” pots, use half, or less, of the recommended amount, since your violet will be processing much greater volumes of water than one that is only periodically watered.

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