Can cabbage leaf be cut and grown again directly in soil?
You cannot regrow cabbage from its leaf, though you can allow it to go to seed and plant those. Note if you do this, however, you may be sacrificing the cabbage head, as bolting will make it bitter. This article will help with growing this vegetable: https://www.gardeningknowhow.com/edible/vegetables/cabbage/growing-cabbage.htm
My cabbage plants are beautiful but won't head up. Why?
It may be that it is too warm or that you just need to give them some more time. There are a few pests that can cause this too. This article has more information on them:http://www.extension.umn.edu/gardeninfo/diagnostics/vegetable/cabbage/headnone.html
If you suspect that it may be heat, mulching well around the base of the plant can help.
I have a raised vegetable bed. I'm a complete beginner. Can anyone tell me how to thin my cabbages?
Thinning is something that you do when you are growing from seed and the seedlings are growing too close to each other. You can either pinch out the weaker seedlings or snip them off with scissors.
If you planted seedlings or young plants and spaced them properly, you do not need to do any thinning.
I planted my cabbage plants over a month ago. They are growing nicely, but when do the heads start forming? I live in Reno, Nevada.
Cabbages mature in 60 to l05 days. This article will help: https://www.gardeningknowhow.com/edible/vegetables/cabbage/growing-cabbage.htm
Is there anything special that you have to do to a cabbage plant to get them to head?
Keep them cool. They will naturally form a head, unless they bolt from too much heat.
I have just noticed cabbage worms on my cabbage and broccoli, as well as their green eggs. I purchased Bacillus thuringiensis to spray; however, the liquid just seems to bead off of their leaves. Does it come in a powder form, or is their something I can add to help it actually stick to the leaves?
You could try using neem oil, which will stick to the foliage and help with the worm problem. Here is more info: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
This article has some ideas for preventing these pests in the future: https://www.gardeningknowhow.com/edible/vegetables/cabbage/protecting-your-cabbages-from-cabbage-maggot-cabbageworm-and-cabbage-moth.htm
How do I make my cabbage plants head?
Keep them cool is about it. They will naturally form a head, unless they bolt from too much heat.