Terminal cone

So in previous years I have noticed that my hops get to a certain height then decide that they've grown far enough and produce a cone on the apical meristem, which is the origin of vertical growth. In Houston this happened at the start of July and last year here in Maryland it was closer to the end of July. The Columbus has already produced an apical cone on the tallest of the shoots and we're still in May:

As with previous years, I'm hoping this will mean that the rest of the plant will begin to fill out and hopefully produce more cones as a consequence. There are already a lot forming on the Columbus:

There's currently no sign of cones (let alone terminal ones) forming on the Cascade:

Or Willamette:

I guess this means that they haven't stopped growing vertically yet. There is still plenty of growing time left this year so I am still very hopeful the Cascade and Willamette will end up being more productive than last year in terms of cones.

I'm really not sure what determines the height hops grow to. It seems to me that at less than 14 feet tall the Columbus is somewhat short of what would be considered normal growth, especially for commercial growers. Perhaps I've ended up with a dwarf variety somehow. It's also possible that they are not getting enough water. I have only actively watered them once so far this year as (I feel) we have had plenty of rain so far. It is also possible they are just not able to transport water any further up the stem than this. I have a vague memory from a botany class a very long time ago that plants rely on evaporation through the stomata in the leaves to achieve transport of water up from the roots. If this is the case I can see that living in an environment with high humidity (such as we have here) would make this more difficult and thus limit vertical growth. This would also explain why (relatively arid) Eastern Washington state is an ideal growing area for them. There may well be a trade off though between having the plant putting energy into vertical growth versus cone production. What is the ideal point for switching from one to the other?

The shorter stature may well make it easier to harvest, so no complaints from me on that front. My biggest concern is successfully getting cones from these plants that I can use in my beer. I suspect the reason for the apical cone appearing earlier this year has a lot to do with these being in their second year of growth and are thus much more vigourous. The Cascade and Willamette still have over a month to produce an apical cone if they are to stay on the same timetable as previous years so I'm not worried at all. I'm still quietly confident that this year will provide an increased harvest compared to last year.