All four of them look like they could be planted much deeper. Just strip off those lower branches and go deep as possible. They are still small enough that they will tolerate transplanting. With soil temps that high you are likely going to have to insulate the containers somehow or provide some partial shade for the plants until the temps fall.

Dave

Liz,

Nice looking 'Tainers!!

Something is definitely wrong for you plants to be turning yellow so rapidly. As Dave says, you need to shelter them either in shade until they take hold, or wrap the 'Tainers in Reflectix (Lowes) to keep them at a lower temperature. I fear you are cooking the roots. Planting them deeper won't help much.

How much fertilizer, and how close to the plants is it?

Raybo

Thanks Dave, would believe that the 2nd planter is already planted as deeply as possible?

Ray - we have some alumafoil that will go on the planters tomorrow. I think we can arrange some temporary shade as well. If these plants were established before this hot weather, would they still be in such distress?

Would it hurt anything to pour ice cubes on the mulch? Or directly on the plastic cover underneath the mulch? The goal would be to lower the soil temp.

As for fertilizer, the first box has the two plants in the middle, and the fertilizer strip around the edge. The 2nd (healthy) planter has the fertilizer strip right down the middle (left to right) with the plants set in the back third of the box.

When I started my own tomatoes, I always grew very strong roots - and still planted them deep. I knew this was overkill for spring planting, but if I ever start them for summer planting, I think I'll do this again!

This morning, the first 2 plants were pretty crispy, so I have given up on this box. For the 2nd one, we wrapped it in reflective insulation, topped the bin with ice and ice packs, and set up shade. The soil temp dropped to 95F in about an hour, though now it's back to 100 at 5:45 pm.

Since my main concern is keeping the soil temps down, I'll move this discussion to the ContainerGardening Forum.

Liz,

Some of my best producing plants are on the covered redwood deck where they only get partial sun. They are out-producing the plants in the full sun. I highly recommend you keep yours under shade cloth or similar protection at this time of year.

Raybo

Liz,
I had some similar problems when I had my containers in full sun. I moved them where they have full sun till around 2 then get partial to full shade as the day progresses. i also moved the containers off the cement and onto soil. My soil temps have dropped and looking great now. JD