Hello there fellow tomato growers,
This is my first year where I'm growing tomatoes in earnest and have been trying to do everything by the book and have learned a lot from this forum. I have some tomatoes in SWC and some in the ground. Overall, the plants are doing well in that they are large and are setting ample amounts of fruit. I have Pineapple and Brandywine fruits growing so I must be doing something right.
However as of late many of my plants are showing signs of stress in what looks like phosphorous and magnesium deficiencies.
I think the phosphorous deficiencies might be due to the colder weather we've had of late. The last two weeks haven't been particularly warm and the nights have been in the low 50s and the humidity has been high. Lately, I've noticed most of the plants in the ground are showing purple new leaves and purplish upper stem growth. When temps were warmer I didn't notice this as much but the plants recently went through a major growth spurt and fruit set.
Secondly, both the plants in the ground and in the SWCs have what look like chlorosis in some of the larger, lower leaves with veins that remain green which would appear to be a lack of magnesium. (from what I've read and pictures - this makes the most sense) The plants in the containers seem to have this condition on more of the leaves than the ones in the ground.
My question is what should I do to tackle the magnesium defiecency and whether I should do anything at this time for the purple leaves? I'm afraid if I apply a phosphorous fertilizer that this may make the magnesium deficiency worse. (I read that high amounts of phosphorous make it harder for the plant to absorb magnesium) I've read about foliar sprays with Epsom salts but worry about spraying the plants with salt. Has anybody used this technique to resolve magnesium deficiencies? How about spraying with a magnesium chelate?
Any thougths on this would be welcome.