Your soil looks pretty wet. Are you overwatering? Also, what is the soil temp?

I agree with David that your soil looks pretty wet and that could certainly cause the yellowing of leaves and contribut to the purpling of stems (because roots are drowning and dying, so can't provide nutrients the plant needs). You can allow your potting medium to dry and see if the plants recover. To help wick the water out, you can put the containers on a towel or something else dry that will absorb the excess moisture.

Once they have dried, don't water until the surface of the soil is dry. I actually lift a pot or two, if it is light, I water, if not, I wait. If water is standing in a tray more than 10 minutes after I water, I drain it using a piece of 1/4" tubinb as a siphon and tip the tray to get as much water out as I can.

Purple stems indicate a problem with phosphorus and is often the result of low temperatures and usually goes away when the plants are in a warmer situation.

If you are using a good quality growing medium, you really shouldn't need to feed your tomatoes unless you carry them beyond 8-10 weeks. Even then you may not need to feed them if what you are using has a time or slow release plant food incorporated into it.

Betsy

Hmmmm....the sprinklers were on this morning so the soil would definitely be wet.....sounds like I may truly be over-watering and will try to dry out the soil and see what happens. I did, however, just change out the soil about 10 days ago and have not watered much since then. Thanks for the feedback. The temps here have been fine, nothing really below 64 for a low so I don't think that is the problem. Sounds like no feeding require at this stage, thanks!

transplanted them to containers using a mix of mulch and potting soil.

Caught my eye. What mulch? What potting "soil"? Besides over-watering issues (which I agree with) that plant looks severely N starved as well as P deprived. Wood chips in this mix binding up the nitrogen? Soil not soil-less mix as is recommended for containers so poor drainage and kinky pH?

Dave

Patrick

Like Dave that is the first thing I thought the problem was, I don't know what part of Florida you are but in my zone 9b we had a lot of damaging rain for a couple of days. Luckily all my plants are doing okay today and the containers are really wet from all the rain.

Here are pictures of different tomatoes and how they look today after the rain.

Some are fruiting already

Some dwarf tomatoes

Silvia

May I ask how many years experience with tomatoes you have?

"mulch and potting soil" leads me to wonder about your planting media. The term 'mulch' just means any organic or non-organic material used on top of the regular soil. Mulch sold in bags at the local store is usually some form of acidic carbon-rich nitrogen-poor material like shredded bark or tree pieces.

My tomato and pepper seeds, started in the basement, are put in a "seed starter potting soil". Maybe that is overkill, but it works for me.

When I initially transplanted the plants into containers I unfortunately could not find pine bark mulch. I was trying to mimic the recommended pine bark mulch, potting mix and perlite noted in the container gardening forum. So, instead I tried a mix of about 1 quart cypress mulch mixed with 4 quarts of Lambert's 100% organic potting mix along with some perlite. My experience tomato gardening is not in Florida but in the northeast and not using containers but simply building raised beds and planting directly in the ground. Container gardening is a whole other world apparently. Anyway, after about 2 weeks I changed out the cypress mulch/potting mix to strictly the Lambert's potting mix noted above..that was about 10 days ago and not much difference in the plants which of course led me to post this scenario. Hope this info helps and look forward to learning what not to do!!

Leaving out the perlite may have not been a good choice. Most potting mix is too water retentive for good healthy growth IMO. Some of them are fine without amending but not many and I'm not familiar with Lamberts. Keep an eye on the moisture level (letting it dry out some before watering) and you may be fine.

I agree with Taz that you will have to watch the watering very carefully unless the potting mix you ended up using has lots of perlite in it. But you also need to feed the plants, not spray but a good root drench of a well balanced fertilizer.

With containers, nutrients leach out of the soil with every watering so maintaining nutrient levels is more complex than with in ground plants. One of slow release granular ferts works well mixed into the soil and then supplemental weekly feeding of a diluted liquid to keep the nutrient levels in line.

But over-watering, especially heavy periods of rains leads to root rot and plant death so before watering stick your finger deep into the soil first. Don't just go by the surface appearance of the soil.

Good luck with your plants.

Dave

Two possibilities struck me, and both would be a form of poisoning. First, cypress contains a substance that retards growth in some plants. And second, it looks like fertilizer burn. I have killed tomato seedlings by fertilizing them in the first few weeks. I think spraying them with Miracle Gro was a mistake. I no longer fertilize or even use a potting soil that contains a fertilizer until my seedlings are at least six inches tall and ready to move into 4-6 inch pots. Even then, I would only use less than half strength once or twice before setting them out.