Question
I am trying to grow a few tomato plants in some pots.  I live in Los Angeles...  I grew them from seed and now they are about 3 feet high.  They have a few green tomatos.  But the plants look very stressed.  I go out at dusk and dawn to look for horned worms and I found a few!  But lately I can't find any more worms and the plants don't seem to be getting better.  Lots of yellow leaves, spotted leaves... and in one case shriveled, tiny leaves.  I bought a bottle of "organic" 3 in 1 (insect, mold, fungus) spray stuff at the gardening store.  I sprayed once, but before I spray more of that, I thought I'd ask your advice.  

Thank you!

Paul Myers

Answer
Paul, the symptoms you've described indicate the plants are stressed. This can result from several factors, but the most likely are a lack of nutrients in the soil or the plants have become rootbound, a very common occurrence when the plants outgrow the pot.

Assuming you used large pots (you would need a minimum 12" wide by 10" deep pot for mature tomatoes), let's focus on the soil.

Tomatoes need a high concentration of phosphorus, calcium, magnesium, and nitrogen, in that order, to produce a healthy harvest. It is very important to use a growing medium that is highly fertile. There are potting soils sold specifically for that purpose. It also is necessary to supplement the feedings every 10 days with a water-soluable fertilizer sold for tomatoes and peppers. These tend to be higher in phosphorus and potassium, and lower in nitrogen. Phosphorus produces more blooms and larger fruit, while potassium produces healthy roots.

Finally, potted plants need to be watered deeply until the water runs out of the drainage hole. Only water when needed. A good indicator is when the soil dries out 2" below the surface.

When stressed, plants become more vulnerable to insects and disease. It sounds like that is what has occurred in this particular case. I would follow the steps I outlined above, and continue spraying them with the organic all-purpose spray until they perk up.

I hope this information helps. Please write again if I can ever be of assistance.

Regards,

Mike