Tomato plant w/ multiple symptoms. Under-watering? Over-Watering? Both?

Question

I'm an absolute beginner so bear with me.

I've started growing tomatoes but I'm seeing multiple problems:

1. Looks like mushrooms are sprouting under the plant.
2. The bottom of the fruit is black.
3. The leaves at the bottom of the plant are curling.

Here is an array showing the (apparent) mushrooms, the black spots on the bottom of the tomatoes, the curling leaves, and then the overall planter.

Based on looking around online I see that the mushrooms are likely caused by over-watering or too much moisture in the soil, and no opportunity for sunlight to hit the soil. But then item 2 (bottom of fruit is black) is most likely blossom end rot -- see the comments at the end of this post -- and the most likely cause of that is under-watering of the plant. Lastly, my research tells me that the curling leaves are a sign of distress, but there could be multiple causes of that distress.

I had been giving the plant a thorough watering 1x daily (I had no idea of the "correct" watering schedule, this was just a guess). I'm located in Southern California so the days have been very hot and dry lately. I've been giving plant food once every 2 weeks per the directions on the box. Am I over-watering? Under-watering? Or do I perhaps have both problems due to the small size of my planter? Any advice on the underlying problem, and best way to fix it, would be appreciated.

Answer 1

As you suspected,the black parts on the fruits are blossom end rot - this is usually a result of erratic watering rather than simple underwatering. Once the fruits are forming, they need calcium - this is transported from the soil through the plant's vascular system and into the fruits. It is quite rare for the soil to be deficient in calcium, but if the watering is insufficient or irregular (maybe you forget one day and do it the next instead, or you usually water twice a day and only do it once for a day or so) then the calcium supply to the fruits is intermittent, and blossom end rot appears. In terms of watering, daily or twice daily in hot weather is probably essential, but generally, feel the top of the soil with a finger - if it feels just about dry, water, if its still wet, don't. Water should always be applied to the soil and roots, not the foliage, to discourage disease.

The toadstools are nothing to worry about - the mycelium for these will have been present in the soil already, and these are just the fruiting bodies and should disappear shortly. If you have been overwatering, that would have encouraged them to form, but they are not uncommon at this time of year.

The container is too shallow, as you also suspected, which is the likely cause of the stress symptom on the foliage - tomatoes should be in a container that is at least 8 inches deep and 6 inches wide, but bigger if possible. Given there is no proper drainage at the bottom, it's possible the soil remained wet for too long, but as the roots grew and took up all the space in the container, it would have been more difficult to keep the plant well supplied with water because of the shallowness of the soil within. You might well have watered thoroughly in the morning or evening, but as the plant matured, it was probably necessary to water twice a day - this difficulty in keeping the plant regularly hydrated would link in with the presence of blossom end rot. If the plant is still growing and producing fruit, then check the soil for dryness morning and evening, to try keep it evenly hydrated. Next year, use a much deeper container...

You can still eat the fruits with the blossom end rot - just remove the rotted parts first.