I have had good success with Kale and cabbage - not much else....

Maybe don't make the soil too rich? For example, after composting well in the spring for a tomato crop, just plant up the cabbage after the toms are done and see where it goes...

Brassicas, especially cabbage and broccoli are heavy feeders so perhaps the composted manure will do the trick. But corn also is a heavy feeder so they should do well under similar fertility conditions as corn. They also do not like an acidic soil so you might want to check your pH. Cabbage root maggots also do a number on them so you may want to check for those. In Maryland, timing should not be a problem. Cabbage should grow from late March to October.
{{gwi:23919}} {{gwi:22564}} {{gwi:22033}}

when did you plant them sunnibel7? this past summer was kind of hot for these crops.

FarmerDill- I suffer from cabbage envy now. :)

I have tried two plantings every year that I have gardened down here: spring and fall. Transplants went out on March 12 this year in the spring (broccoli, cabbage, kale, cauliflower) and then mid-late August for fall (broccoli, kale, collards, cabbage, sprouts). My soil pH is 6.1 according to the soil test done in August- too low? It was also a bit low in Ca but I did add lime when I planted the fall crops. Perhaps too soon to see a change from that? No signs of root maggots when the spring plants were removed. We do get these awful harlequin plant bugs that have population explosions on anything in the mustard/cress family in the heat of summer, so I pull out anything that might harbor them in summer. Except the horseradish. Anyway, I tend to choose early maturing varieties to help me get around that little miracle of nature.

It's hard for me to know what is caused by something I'm doing/not doing and what is a result of being at the new house with its different soil. I guess I wonder most of all about the cabbages that refuse to head. (They did that at the old house too.) What makes them decide it is time to head up?

Time usually. What variety are you growing? Some varieties will head in a couple of months, others take all summer. You did say early varieties , but they also vary all over the place. pH of 6.1 should be okey, but the lime will help, they do best at 6.5 -7. Harlequin bugs will stunt them, so you need to keep those in check. Your planting schedule seems fine except for Brussels sprouts. Those take a lot of time, so you need to move up your transplant schedule.
Not a great Cabbage but it fast to head Earliana {{gwi:133174}}
A cute little cabbage that is more reliable than Jersey Wakefield {{gwi:133175}} Quick Start , a few days later but dependable and a decent size with flavor. {{gwi:10237}}

Let's see, this year it was "Salad Delight" from Burpee. A red supposed to be ready 50 days after setting out plants. They just stopped growing both spring and fall and sat there looking little and open. To be honest I didn't do much more than note it each time, being unsure what was happening or whether I should interfere.

When would you put out the brussel sprouts? I started them at about summer solistice, but they were my first from seed myself. They did catch up to the ones I bought when I set them out, but then both sets stalled out. That's the best way I can describe it, stalling out. Not struggling or losing leaves or color, just stalling.

Corn is a very heavy feeder. If you grew corn in this spot in the summer that may be part of the reason you're not having good growing now. I'm in Houston and we never grow kohl crops in the spring. They bolt really fast because it starts getting hot.

I always grow broccoli and cabbage, but don't expect them to head until Feb or March. Brussels sprouts, same thing. Usually they sit there growing a little until spring, then they take off.

You could be growing lettuce now, too, if you aren't already.

I am not sure of your area in Maryland, But I used to live across the river in the Northern neck of Virginia. Transplanted Brussels Sprouts in July so That they would start to head in October. Clipped the tops around Thanksgiving so that the heads would fully develop along the stems.
I don't grow red cabbage often, so don't have experience with any other than Mammoth Red Rock and Red Acre. Those varieties seemed a bit more temperamental than green varieties.
Next spring you may want to try digging 12 inch holes about 8 inches deep, filling them with a half soil, half composted manure mix and setting your transplants in that. If that does not work, you have other problems than fertility.

Thank you everyone!

Just to clarify, I did not plant the cole crops in the same spot as the corn, they were both planted in the same new garden. The soil in both rows was treated the same, though. :)

FarmerDill, You can't have been too far off from us as the crow flies, Due west from my house puts us about 5 mi north of the 301 bridge. Leonardtown, which is about 40 minutes south is across the river from Montross.

I never knew that red cabbage might be more tempermental than green, maybe I will pick up a little pack of transplants come spring to trial against my home-grown red. I just liked red to get a wider variety of anti-oxidants in our diet. I'll try the hole with compost mix this spring and see. Thanks for the specific reccomendation to try, on my own I probably would not have used as much and might find myself still wondering come next year. Now I just have to figure out a gameplan for those darn harlequin bugs, if I'm to have brussel sprouts. Like squash bugs they seem pretty bulletproof.

Cheers!