Bugs usually get mine in the summer, then the first frost kills the little pests. Mine look like yours now and I may not plant anymore in the spring and just plant in the fall.

Im guessing its a nutrient issue, if its bottom leaves yellowing the falling off it could be a nitrogen def. Could you take a closer pic of the leaves with the issues?

In my experience the bottom leaves always fall off kale and Brussels sprouts in the winter and it has nothing to do with nutrients. It's just normal behaviour for old foliage late in the season.

I've had kale that retained its lower leaves into the 20's no problem, definitely not loosing leaves too the extent his are. Brussels i cut the leaves to promote sprout growth.

Kale has a pretty high nutrient needs in big plants. In hydro i run my 12" taller plants at 1200ppm, soil they get a very large dose of blood meal going into late fall. Wish i grew kale this year so i had some pics of them goingo.

Have you looked close for pests, As i zoom in it looks necrosis and blotchy on leaves. I also see lower dead leaves sitting at the base of the plant, if it is bugs this provides a nesting ground for them to breed. Def recommend to remove them and throw in the compost pile or trash.

Well, I certainly agree on clearing up fallen and yellow leaves and keeping the air circulation around the stems. I've just been doing that on my kale and broccoli on the allotment. But I still don't think it's worth sweating over some manky leaves in mid-Winter.

Yeah, but it'll give Him a better chance to successfully sustain a larger harvest next year if we can pinpoint The problem now.

I was assuming, since these are biennials, that the harvest would be through this winter and early spring. Next year the plants will flower and would normally be pulled.

You are in a warm zone, I remember seeing kale and chard look exactly like this when I lived in Hawaii because they never actually stop growing. If you're not picking the leaves soon enough, they eventually just go into senescence and die off as they age. If it is still growing new top growth that looks healthy and it's just the large older leaves that are yellowing, I wouldn't worry too much about it, just pick them when they are still young, green, and tasty.

I think with nitrogen deficiency, it's the newer leaves that yellow first, but I'd have to dig through some books to make sure I'm remembering that correctly.

I saw some in the Santa Monica community garden that looked just like this, only about 5-6' tall. They seemed in really good shape. I agree, this looks like the growth habit for mild-winter areas. Pick & eat, it should be fine.

I think i found my answer by accident. They are kale trees, i think. If so it is perfectly normal.

Chuckwagon009, I cleaned up the leaves on the ground as . It was a reminder that i need to eat more kale, but oh well. Maybe making kale chips will help.

I've been giving them more organic compost and worm castings from mainly fall leafs. Now leaves are starting to come out the trunks of a few of them. I'll post a pic when the side growth is better.

I noticed the tallest one is starting to bolt, so i chopped off the very tip of the plant hoping to stall the inevitable.

Thanks everyone for your input.