Yellowing Plants

Help! I just moved to Whittier, CA. I've always been a good gardener. . . indoor and out. My yard was the talk of the neighborhood (yes I'm bragging). So the first thing I did was start buying new plants and many of them (mostly the potted plants) are turning yellow. What could be the problem? Is their something weird in the water down here? Please help me before all my plants die. I usually use one of those little water prods to see if my plants are due to be watered, and it's worked before. HELP!

Hi Frances,
Some of the most common reasons plant leaves yellow are:
Too much water, constantly being wet
Lack of fertilizer
Lack of iron
There could be other reasons as well, but these are probably the most common.
Be sure the containers have large holes in the bottom so the excess water drains away. If the pot is in a saucer, remove any excess water remaining it the saucer after about an hour or so. I think once in a while you should also use your finger to 'test' the soil to see if it is moist or dry. Sometime the probes can give false readings.
Your plants are always using 'neutrients' out of the soil. Those neutirents should be replaced on a regular program. For most liquid plant foods including water soluble, it is usually about every two weeks. Dry foods once a month or so. Some slow release will last much longer, read the labels.
Often the soil mix lacking iron can cause yellowing. This is 'usually' identifed by looking carefully at the leaves, if most of the leaf is yellow with the veins being green, this is usually a lack of iron. You can buy iron by its self or in the plant foods you buy, you need to read the label.
In So. Calif., often the water is 'alkaline'. The alkaline salts build up in the soil and it makes it difficult for some plants to absorbe the plant food, even if it is applied as directed. You can help counter act the alkalinity, if that is the cause, by a good deep watering about once a month to try to 'wash out the salts' that have accumulated. You should try to time this with your fertilizer applications. Usually flush the soil, then the next day apply the plant food. Also you can buy a simple pH test kit at most nurseries and garden centers. Quite inexpensive, for what you might learn.