AboutMike Mascio Expertise I have been an avid gardener since 1985 and an AllExpert volunteer since
1998. I specialize in soil preparation, seed starting and plant
propagation, flowers, vegetables, and general landscaping. I am a strong
advocate of the square foot method of gardening and the use of organic
controls for pests and diseases.
Question We have several tomato plants (different varieties), lots of blossoms and
already some small fruits. But the leaves on some of the plants are turning
yellow. One or two plants look yellowish all over. They are all in plastic
containers, at least two gallon size each. We live in No. CA near the ocean so
the days can be overcast and foggy. Can the yellowing be from too much
watering? We have been fertilizing about once a week with a organic blend
(6-4-4). Too much fertilizer or maybe not enough. Any advice would be
greatly appreciated....
Answer Jennifer, both of the possibilities you mentioned are the primary reason for yellow leaves on container-grown plants.
Excess water depletes the soil of nutrients. Since soil is the primary source of nutrients, it is imperative that you use a fertile potting mix and only water when the soil dries out. Excess water also saturates the roots, making it very difficult for the plant to absorb oxygen and nutrients.
My advice is to only water after the top three inches of the soil dries out. You can purchase a water meter at most garden centers for less than $10. These are very accurate and are a must for plants grown in containers.
You are definitely fertilizing too often. Most plants should only be fertilized once every 14 days, even less often if you have fertile soil. Fertilizer can burn the roots when applied too often or at a higher ratio than what is recommended by the manufacturer. This is even more prevalent with containers since the soil area is so small. It is a good idea, however, to continue using the organic brand.
I hope this answered your question. Please write again if I can ever provide assistance.
