Your location please so we have at least an idea of how long your growing season is and how close you might be to needing to harvest them? Have the tops started to lay over on them? If not then there is no need to harvest them yet and no need to stop watering them.

If they are laying over and beginning to dry out so harvest time is coming soon then you can reduce or stop watering if you wish but it isn't required.

With drip tape you can shut it off at any point along its run just by folding it back on itself and clamping the fold with one of the end clips of anything else that will hold the bend in place.

Dave

I'm in north central Illinois. If I'm reading you right there should be a period of time when the watering stops before harvesting. As to the drip line it seems the onions should be at the end of the line (this part of the question is for plans for next year when I set up the drip irrigation in case anyone is wondering) otherwise when I fold the tape back on itself it will cut off everything after the onions unless I'm not thinking straight. Thanks digdirt for your response.

sheesh I'm sorry make that east central Illinois. I think the eclipse must be blacking out my mind as well as the sun.

No I'm not saying that. Just that it is an option you can experiment with if you wish. Some argue it intensifies the onion flavor if you do, some research says just the opposite, that the flavonoids are varietal and not affected by reduced watering.

I'd hazard the guess that most gardeners do not reduce or shut off water for their onions as they want maximum growth and development out of them before harvest Reducing the water only stresses and speeds up the plant die-back.

It is your choice to try or not. However even those who advocate it only recommend doing it AFTER plant die-back and top collapse has begun. So have yours started to die back already? Mine haven't.

As for the drip line - yes they would have to be at the end of the line.

Dave

Thanks digdirt it certainly would make it a lot easier. What I have in mind is to maybe have a shut off valve for some lines (maybe not even go that far) but generally just water everything in unison as much as possible.

Do keep in mind that different crops have very different water needs so if your plan is to "water in unison" then you will have to organize your beds according to the water needs of the crops in it. That can be difficult as different crops have very different nutrient needs so you'll need to keep that in mind as well.

The easiest solution is to give each crop its own bed that can be watered and fed as it needs. But that isn't always possible to do so as much flexibility in your water set-up as possible can be a big help.

Dave

in terms of your drip line if they are being watered somewhere in the middle of your drip line via emitters that are coming out of the main supply hose, I assume you could take out the emitters and plug those holes with "goof plugs" so that you still get water downstream to other plants but your onions would dry out.

Thanks Sabrina I wasn't certain if drip tape worked the same way with goof plugs as drip lines or not. I think my easiest course may be to set up the onions at the end and then either not bother as digdirt suggests (in which case it really doesn't matter where I plant them) or shut off the end of the line by folding back the drip tape. It may turn out to be too much work, but I could use the old tin can method and bury a tin can next to those plants needing more and extra water and then simply water any given spot the smallest amount needed by all plants in the area served (think least common denominators).