Question: What is the best fertilizer to use on African violets?

Answer: The answer is ever-changing, because fertilizers seem to come and go frequently. The best fertilizer for you will depend on the source of the water you are using and what is or isn't in the water as well as the pH of your water. The temperature of your growing area may also affect your choice.

Almost all fertilizers offer the basic three "macro-nutrients" of nitrogen, phosphorus and potassium which are needed in ample supply for healthy plant growth. A few also include the "macros" of calcium and magnesium. Since these two latter "macros" are found in many city water supplies, most growers will get enough calcium and magnesium from their water. If you use rain, distilled or reverse osmosis water, be aware that you need a fertilizer that contains both, or you will need a supplement (commonly called Cal/Mag) to supply them. In the past, many growers chose fertilizers with a high "middle number" (phosphorus) because it promoted blooming. There may be some value in boosting phosphorus briefly if you are a show grower, but be careful because too much can damage foliage and hurt the plant.

Many fertilizer brands also have and list "micro-nutrients" which are needed for healthy growth, but in very small amounts. Not all brands list the "micros" but they can be very important. Sulphur, for example, tends to lower pH in the root zone. If you have problems with high pH (over 7), a fertilizer with sulphur will help you control your problems and bring your pH into a more desirable range of 6-7. But if your pH tends to become too acid (below 6) then sulphur will make the problem worse. If you use well water, or live in mining regions where your water supply may carry high amounts of specific minerals, it is possible for your violets to show symptoms of toxic levels of a micro-nutrient. This may cause irreversible stunting of center growth which looks very much like the violet has mutated to a miniaturized version of the original. It helps to know what your local water supply contains and to choose your fertilizer accordingly. If you use rain, distilled or reverse osmosis water, you will want a fertilizer which promises all the micronutrients needed.

Choosing a fertilizer according to the source of the nutrients is also wise. Fertilizers listing their source as urea nitrogen are often the cheapest and also the least desirable. If your growing area is frequently colder than 70 degrees Fahrenheit, a fertilizer made from urea is more likely to result in ammonium toxicity. This is because the mycorrhizae (soil bacteria which process nitrogen into a usuable form for roots to absorb) are inactive at cold temperatures - ammonium toxicity becomes more likely if fertilizer is sourced from urea. Fertilizers using ammonical nitrogen or nitrate are a little more expensive but are generally better quality less likely to pose problems.

It is often wise to ask others in your area which fertilizer works best for them. Some growers like to rotate and use different fertilizers during the year, using balanced formulas during times when more growth is desired and high phosphorus formulas when preparing for show.

Fertilizers currently (2020) being mentioned by many growers in social media (especially to use with rain, distilled or reverse osmosis water) include either DynaGro Grow 7-9-5 or Feed Me MSU fertilizer for African violets (from repotme.com). Also recommended is Better Gro Orchid Plus 20-14-13 without urea, which is also preferred by many growers of other Gesneriads. Jack's Classic formulations generally lack sulphur and may be useful for growers with acid growing conditions. As always, read and follow package directions (do not exceed recommendations) for best results.



Question: Is it okay to use a fertilizer with urea? I use fluorescent light and average 24 degrees (centigrade).

Answer: Urea-based fertilizer should not cause problems for you if 24 C is your usual temperature for growing. The exception to that would be if your soil pH were quite acid. The symptoms of ammonium toxicity (the result of using urea-based fertilizers in cold or acid conditions) are generally seen on the leaves or in the root system.





Question: The only peat moss I have found in bags also has fertilizer in it. Can I still use fertilizer in the water every time I water or will this be too much? 2)The fertilizer I have is 12-14-12 and says to use 1/2 tsp per gallon of water. Should I dilute it even more then? 3)I haven't found any peat moss without fertilizer unless you can use the kind you buy in bales that you would use in the garden. If you use this kind I thought I read somewhere about having to sterilize it. Is this true and how would I go about it?

Answer: If you have no choice except for the fertilizer-charged potting mix, then you do not want to fertilize for about three months. This is why we dislike potting mixes with a fertilizer charge - you really don't know at what point you should begin fertilizing.

If the fertilizer recommends this rate for once a month fertilizing, and you are going to use it weekly, you should dilute it to no more than an 1/8 tsp per gallon. If this is their recommendation for weekly watering, I would still dilute to 1/4 tsp and then watch. If you see fading vigor then a bit more might be good. However if you see yellow spots or edges around the perimeter of the older leaves, you are over-fertilizing and need to cut back the rate of feeding.

If you choose a bale that has no tears or cuts, the peat should be safe to use. Rather than sterilize the potting mix, the goal is only to pasteurize it which is done by heating the damp mix just to 180 degrees F and holding that temperature for thirty minutes. Sterilizing it (at a higher temp) would destroy the beneficial bacteria that enable the roots to absorb nutrients.



Question: I was told to water my African violets with warm tea. What does this do and is it okay? What brand name fertilizers are okay to use on these plants, as mine have great foliage but are not blooming although I have them in a window with north light.

Answer: There isn't anything obvious in traditional drinking tea that would be beneficial for African violets, although some teas might help amend the pH or provide some nutrient that the African violets need in tiny quantities. I would be very careful about using "warm" tea, since it is not good for a plant to have a sudden change in the temperature around the roots... a change of more than ten degrees (either colder or hotter) can result in spotting on the leaves because of root damage.

Some growers (especially those who prefer organic methods) create a tea using various composted materials (straw, manure, eggshells, etc.) which dissolve as the water stands. These may be quite smelly, are of unpredictable strength and composition, and usually better for use in the garden than inside. There are a number of good African violet fertilizers which will probably be more effective. Use according to package directions, erring on the side of using less rather than more than recommended.

In a north window, you may not be getting enough light to the plants to get them into good bloom. The ideal window seems to be an east-facing one in which the plant receives bright morning sun. On the north side, the window must be fairly large and the African violet must be sitting so that it almost touches the glass. Having a building nearby that reflects light into the window can also really enhance the quality of the light. If you suspect inadequate light, you may need to supplement it with a little artificial (fluorescent or LED) light for up to twelve hours a day. For more blooming tips find the article “Blooming Secrets” on the AVSA web site.

Question: The first time I repotted my African violets, I lost some plants due to shock, I believe. How can I prevent root shock? Will extra Superthrive help?

Answer: Many growers do use Superthrive with good results, but I would not recommend using more than the package suggests. I find that I rarely have shock if using a light porous potting mix (equal parts of a quality potting mix and coarse perlite) and if the plants are enclosed in a clear container or bag (set away from direct sunlight) for about one month after transplanting.

Updated 07-2020