The leaves on my plants are turning yellow.

The most common cause of yellowed leaves in aeroponic growing is using well, softened, spring, or very "hard" water which is outside a normal range of pH or dissolved mineral content. While these types of water may be excellent for drinking, they can cause problems with aeroponic growing because the dissolved minerals or strong pH can interfere with the proper uptake of the AeroGarden nutrient/pH-buffer tablets by the plants. This can prevent or retard germination of seeds, severely stunt growth, and cause “chlorosis”, or yellowing of the leaves. Be aware that most water filters do not remove these dissolved minerals, as described in more detail below.

Even if you are using municipal tap water, over time the pH or dissolved mineral content of your AeroGarden's water can occasionally become too strong or too weak.

Most municipal water supplies are treated so that they fall within a certain range of pH and dissolved mineral content, which works well with the AeroGarden. However, if you have been using well, spring, softened or very "hard" water, we recommend that you switch to using inexpensive bottled water labeled "drinking" or "distilled" (not "spring" water) available at most supermarkets. If accessible, you could also refill water jugs from an ordinary, municipally-treated source (that is not softened).

To correct the problem of yellowing leaves, we recommend that you do what is known as a "Rinse and Refill" (for detailed instructions, click here), and if you have been using high mineral-content water, switch to using bottled "distilled" or "drinking" water. After performing a rinse and refill, it may take a week or two for plants to recover and begin growing new, green growth. 

About Filters and Water Softeners

So-called “hard” water has a high dissolved calcium and magnesium content, and is common in mountain communities, parts of Florida and the desert southwest. While this is not harmful to drink, it can cause deposits to form in pipes, tea kettles and bathroom fixtures. Many apartment complexes install water softeners at their source to prevent mineral build-up in pipes. Water softeners work by displacing magnesium and calcium ions with sodium ions, which do not cause deposits in pipes, but which still cause problems with aeroponic growing.

Some people with water softeners remove the sodium ions prior to drinking with a reverse-osmosis water filter, which will do a good job for drinking water, but which unfortunately does not seem to correct the problem from an aeroponic-growing standpoint. If you are on a well, however, a reverse-osmosis filter may work for your AeroGarden, provided the pH is not too high or low.

Be aware that most home water filters, however, do not remove dissolved minerals. They are designed to remove contaminants such as organic solvents and chlorine taste, but dissolved minerals generally occur as tiny ions which are too small to be filtered out. The only filters that remove minerals are high-quality reverse-osmosis filters and the commercial “de-ionizing” filters used by certain manufacturing industries. Again, if you are using a reverse-osmosis filter on water that has previously been through a water softener, you may still have problems using the water in your AeroGarden.

Distillers do remove minerals, by heating, vaporizing and re-condensing water and leaving the mineral deposits behind. Pure distilled water works very well in the AeroGarden, provided it is within normal pH range.