Thanks for the quick reply to my inquiry. I wonder if I snip the topmost leaf off at the right spot will that promote side sprouting while presrving the rest of the existing leaves? I will experiment as you suggest. BTW the collards have been the most vigorous, though some of the kale has gotten a little taller that the collards, but skimpier looking.

Some clarifications. My main goal was to keep the cabage worm moths out since we were so heavily infected last year (our towers were mainly chicken wire with window screen celings, which only discouraged the squirrels), so I focused on the cabbage worms.  I shielded the plants with what was available, using 1/4' or 1/2" hardware cloth where I had enough, and window screening material wrapped on the chicken wire towers where I ran out of hardware cloth. All ceilings are window screening.  I minimized the use of screenng because it cuts out so much more sunlight. I can see the difference in the plants---the ones with less screening more hardware cloth on the towers are more vigorous. The Earth Box is  1/2" made hardward cloth on 3 sids and some of the back, with a plastic panel in the rear which never faces the sun. The ceiling is window screening. That is the one doing the best. The rest are pots (2 of them in the red wagon at the edge of the photo) and have a mixture of materials on the sides (towers) and window screening on all celings. I have not seen any cabbage worm moths yet but I expect them to be excluded. My spouse thinks they will get through the 1/2" hardware cloth, but I don't. I realize other insects will get in.  We probably had aphids and white flies last year.

I have never used insect netting/row covers, but I realize that would have been the better option to wrap around the towers. Maybe next year. I have to be around and diligent to get enough sun, moving these 4 platforms multiple times per day-- and each year it gets worse--that I did not want to lose sun to a covering that would cut a lot out, like the window screening does. I don't know how insect netting/row covers compare to the window screening (fiberglass?) that I am using. 

Appreciatively,

Mark

I followed the idea of cutting  the plants off near the soil when they (collards and tuscan kale growing in containers with a screened top) became too tall for the space available at the top. I snipped thru the stems about 1 1/2 inches from the soil. Out of 5 or 6, two sprouted leaves just below the top of the stumps and became bushy plants with lots of side stems. Hooray! 

However, three shriveled up and turned brown, with no new growth at all---dead. The successful ones ocurred first-- the failed ones a few weeks later when it was much hotter. Could temp have played a role? 

My question, now, is how to"replace" the lost plants. All the plants are now too tall for their space. I am wondering if I can cut healthy looking collard or kale leaves and try to root them in water for creating new plants. Will a single leaf with some stem sprout roots like oregano, sage,eg, will?

Fall should be cool and I believe I might get some growth once I have "rootlings," altho diminishng sunlight wil be limiting.

Thanks for your response. Too bad, I was hoping I could propagate the kale ur collards with a "sprig" in water. Buying seed or new plants is the obvious alternative, but I had not thought of it, since pruning had worked initially (cooler weather, I am guessing).

Mark