It could simply be a difference in temperature of the soil. Not sure what the weather has been like in your area over the last month or so, but containers will warm with the air within hours, but the soil 6-12" down in the ground will take weeks or more.

It's a double edge sword, of course. Come the real heat of summer the container plants may require shading to do as well as the in ground plants, particularly since the inground plants are mulched.

What you might wish to do if you suspect a soil temp difference is rake back the mulch until the ground plants take off.

Ahh, I didn't think about that. The containers are mulched as well, however, they are black, and now that I think of it they also get more sun than the in-ground bed does. And here I was worried that I had a soil issue!

Thank you for pointing that out. I am going to paint the containers white pretty soon, as I don't want to cook the roots when we start hitting high 90's on a regular basis. We've been hovering around high 80's with night time temps in the mid-upper 50's.

Thanks!
:0)

You might have mixed results trying to paint the tubs -- plastic doesn't take paint too well. Easier, and probably would work better, to hang opaque cloth (supported by stakes) just in front of, and around, your tubs. I use 90% shade cloth. As an added benefit, the cloth will protect the tubs from UV as well.

-Bruce

Thanks, Bruce! I will go pick up some shade cloth. It sounds a lot less messy, and it will probably look a lot nicer as well. I had contemplated building planter boxes around them, but I have so many containers that it would be a time consuming project, and likely an expensive one for all of the wood. :)

JAG- I'm going to rake back the mulch in the bed for a few weeks and let the warm, 80's temps heat up the soil a bit before putting it back.

Krylon "fusions" spray paint is made to be used on plastic and has worked great for my SWCs while also providing UV protection for the plastic. They are available at Home Depot and a can will paint at least 3 27 gallon containers.

Below is a pic of several of mine with dark green paint (the ones with the yellow covers). There are also many other colors like tan if you want something lighter to reflect the sun a little more.

Black plastic mulch can help with early planted in ground tomatoes, it helps warm the soil, it made a huge difference for me this year. I personally have had better taste results with in ground tomatoes than containered ones. However I will admitt that I have more experience with growing tomatoes in ground than in containers. I have changed my fertilizer program and growing medium for my containered plants this year, so we'll see if it makes a difference in taste.

Damon