Q.Tomato Plant Issues
We have 3 different tomato plant varieties, each 1 in about a 10 gal plastic pot each. Various issues include self decapitating blooms on 2, yellowing leaves, and tops of 1 that are dying off. I also am noticing 2 plants’ leaves are starting to gray & not sure if it’s a prilim problem starting. Watering about half gallon each morning & getting sun for easily 6-8 hrs /day. Currently on concrete in roll-around bases with gravel in the bottom tray to help drainage. I have pictures but cannot see how to attach/include them.
Certified GKH Gardening Expert
Yellowing with spots would indicate Alternaria leaf spot, which is a kind of fungus. Here is more information: https://www.gardeningknowhow.com/edible/vegetables/tomato/early-blight-alternaria-tomato-leaf-spots-yellow-leaves.htm
It is not necessarily a death sentence for the plants, but could reduce production on the plants. Treat with fungicide about once a week to keep things in check.
I know Ann and I gave conflicting advice regarding watering, and with good reason. It is because we do not know the drainage situation of your containers. I am assuming that the containers have good drainage - in which case they will dry out rapidly in very warm weather. Ann is assuming (I think), less drainage, which would result in flooding the roots. Both over watering and under watering have the same symptoms.
To resolve which advice you should follow on watering, check the top of the soil before you water. If it is dry, follow my advice. If it is wet, follow Ann's advice. :)
Certified GKH Gardening Expert
I would increase water to 2X a day, making sure that the soil is drenched to the point that it runs out the bottom. Most of the issues you mentioned can be attributed to underwatering.
The graying leaves may be powdery mildew. This is often caused by wet leaves. When you water, try to water near the soil to keep the leaves dry and if you water in the afternoon/evening, make sure there is enough daylight left to allow the leaves to dry before nightfall. The condition should clear up on its own if you do this, but if you want it to clear up sooner, you can treat the plants with a fungicide.
Thank you Ann and Heather for your help. At the time our weather had been pretty warm (hi 80's +). I did only water at the soil. The 3 plants are in large pots. We've had now a week of off n on rains and mostly cloud cover. One of the plants is getting a lot of yellowing leaves that appear to be having dark spots on the leaves. Seems like a disease. Will trim of those effected leaves or branches. A dose of water/miracle grow helped previosly. Doing again today. Can the fertilizer help against diseases? Or once they start is it to late? Thanx again for your inputs.
It sounds like they are too wet. 1/2 gallon water daily is a bit much for anything less than a large plant with huge fruit set. Tomatoes like their soil to be evenly moist. To check how moist the soil is, feel under the soil level 3-4 inches. Also, it's best to water thoroughly less often rather than to water more frequently thus keeping the top of the soil ball wet and not promoting rooting throughout the pot. Depending on the tomato variety and type soil in the pot, I would suggest watering with a gallon of water/fertilizer up to twice a week. Remove all yellowing leaves and discard.