In my experience, no container will grow a cabbage that large.

Here is what I would do. Dig a hole 3 feet deep by 3 feet diameter and toss all the subsoil aside. Then fill the hole in with good topsoil and lots of compost. You can use cow manure if you don't have compost available. It will take about 100 pounds of manure/compost to do the job. If you choose to use commercial fertilizer, you can put 1 cup of 13-13-13 in the hole and mix thoroughly with the toposil and compost. The hole should be completely filled in and mounded up nearly a foot high when you are done because it will sink down as the plant grows. Plant your cabbage in the top of the mound and water it thoroughly. If you want to use miracle grow of similar, use only very weak at first. It is best to use a water bucket to provide water. You can make one from a 5 gallon bucket with a few small nail holes near the bottom. The water has to seep out slowly. Keep it watered and fertilized as it grows.

DarJones

My cousin gave me one of these cabbage plants from his school.

I planted it about 3 weeks ago. It is beginning to grow rapidly.

The plant I received is an 'O.S. Cross Cabbage.'

I have never grown this type but I expect it to want lots of water.

I think it will be interesting to track the progress of your plant.

yeh i reckon you would,ahve to ahve it in the garden and in a very good medium well fed, one example i saw recently from ireland i think was huge i mean huge i would take me 6+++ months to eat it(would only need to grow one for self consumption), they used human urine to get it to this level, i use urine i get large cabbages but reckon our winters too short and mild to get them any bigger, get them around 5 to 7 kilogram size.

so start with a garden full sun and good watering and nutrition all you can do the rest is up to nature. also no guarantee the seed/seedling will grow true to form, lots of variables.

len

Here is a link that might be useful: lens garden page