You have learned the same lesson - and rather expensively so - that many of container gardeners have come to realize: Miracle Gro potting soil - Moisture Control or not - is just not a good soil mix! Far too uniform and small a particle size and the ability to retain too much moisture. Products like this will always produce a fairly high perched water table or the area towards the bottom of the container that permanently remains overly saturated. This always runs a high risk of producing root rots and contributing to other fungal issues.

I would suggest adding bark fines and enough so they constitute at least 50% of the mix. Ideally, they should be the highest percentage of the mix ingredients, at about 2 times the volume of a "regular" (read 'inferior' :-)) potting soil mix.

$200 bucks is a lot of MG soil at around $10 per cubic foot - how big are your planters?? btw, I'd recommend looking for cucumber starts at your local garden center as it is getting a bit late to start these from seed. You'll save about a month of growing time with starts.

I agree. The only thing you can do to help would be to add pine bark mulch. As in 70% bark to 30% MG moisture control.

@gardengal48 - I like growing them from seeds. It's just the way I roll, I guess. My goal is to harvest seeds and be completely self sufficient, aside from fertilizer. I have four 4ft x 1ft planters and I used it with peace lilies and jalapenos, as well. Only the cucumbers are upset, and a few of them are still fine, while a few others are possibly dead.

I'm trying to save them, just because why not, and while I'm starting another batch, and I can't find how best to prune them. There are quite a few crunchy yellow and brown leaves, which I assume are completely unrecoverable, even if the plant did spring back to life.

Do I prune them at the base of the leaf, or take the stem, too, pruning back to the vine? I've been pruning back to the vine, but some of the stems still look somewhat healthy, though very limp.

Also, it looks like we're going to have about a week of full sun here in central Texas. Should I drape the vines out so that they get the sun, or leave them in the partial shade of the patio? Or does it even make a difference at this point?

I will definitely get some pine bark and start mixing it in, thank you for that!

You plan of being self-sufficient with the veg garden? How many acres to you have?

I don't believe mixing with topsoil or any "dirt" will solve the water retention issues. Pine bark is needed to help it drain.

MG moisture control holds onto water for a long time. The lower half always stays wet, that's why roots would only grow on the top layer.

@Nil13 - No. I want to be self sufficient at whatever I'm planting. For instance, if I plant cucumbers, I want to harvest the cucumber seeds and grow them from seed the next year.

Thank you guys for the help. I haven't decided if I'm going to mix it with pine bark or just replace it with regular potting soil yet. Probably the latter. I'm going to talk to the apartment manager tomorrow about throwing it all in this one barren area near our patio and growing something there, using the MG stuff as a top layer only.

So...starting new, what soil should I buy for planting new cucumber seedlings? I don't mind watering often (Texas), and I don't mind fertilizing (thought I don't have compost yet).

If it were a raised bed, I would agree with mixing in topsoil but for a container absolutely not. That won't help. Containers work best with container media. Raised beds work best with a high quality field soil.

Ahh, I see what you mean about being self-sufficient. That's typically a beginner thing. I think we've all been there. Seed saving is a PITA and when a pack of seed that can easily last 5-6 years is only a couple bucks, why bother? Plus, the odds of actually getting the right variety for your location on the first go is practically zero. Seeds are cheap and will last a long time in the refrigerator, and even longer in the freezer.

Got my new moisture meter today. Tried it on one of the two planters that still has living plants in it. Top inch to 1.5" DRY. A few inches deeper, moist. The entire bottom half, very wet.

So I guess I have some anti-cucumber soil. Oops.

What can I even do about that? I shoved some string into one of the drain holes and out into an empty bowl in hopes that it will wick some of the moisture out of the bottom...

That is 'anti-container soil':)

I would take it out and mix with lots of small bark and maybe some perlite, leaving approx. 20% soil only. Plant new plants in it and fertilize.