The Question Corner                                                                   By Nancy Manozzi

Question: What is that slimy green stuff I see in my wicking reservoirs and is it harmful to my African violets?

Answer: Algae! Algae is one of the simplest organisms among plants. African violet growers may recognize it as a green slime noticeable on clay pots or floating in the water of self-watering containers. In most cases, algae is more unsightly than it is harmful. However, in certain types of watering devices, algae can inhibit the absorption of water into the soil. And, Dr. Jeff Smith has found that algae on the soil can be a problem with seedlings. Anytime he got an algae mat growing on the germinating bed or on the soil of a young seedling, the seeds or seedling didn’t germinate well.

If you find algae growing on the side of your pot, use warm water to wipe the pot clean and increase the amount of air circulation between your plants. A glazed or plastic pot is best since they will cut off the water supply that otherwise soaks through an unglazed pot.

If you find algae growing in the self-watering device, empty the water, clean the container, refill with fresh water and replace the wick with a new one. If you’re using capillary matting as a wicking method, run the matting under warm, soapy water, being sure to rinse ALL the algae off the material. Dr. Ralph Robinson (Rob) has learned to use dark colored, acrylic blankets since algae is less likely to grow on dark surfaces.

To prevent the growth of algae in your self-watering containers, the safest method is to simply cut off its supply of light. The type of algae that grows in these containers needs a lot of sunlight. By shading the area around the device (though not the plant), you will cut off the supply of light that algae needs to thrive. This can be accomplished by using opaque or colored pots.

And, a last good preventive measure is Physan 20, a relatively safe algaecide. Add ¼ to ½ teaspoon to every gallon of water used to water your African violets. Physan 20 may also be used to keep your capillary mats from turning green.