I've seen it done with plastic mulch but they were using a transplanter designed to plant through plastic. Looked like it worked well and they got very nice looking, large onions. You could do it by hand - I think all you would need is a small hole through the plastic perhaps a pointy stick to make both the hole in the plastic and into the soil - but as you say time is a factor. However, if you can plant then forget about needing to take time to weed you may find it actually saves time in the long run. Aside from that a good pre-emergence herbicide does help a lot. Also if grasses are a problem you can use Poast as a post emergence. It works very well. As to broad leaves, to the best of my knowledge there is nothing that work post emergence in onions as a spray. I have, however, use a pipewick applicator and glycophosphate (read generic Round-Up) between the rows. It looks somewhat like a hockey stick made from 3/4 PVC pipe with a cord along the bottom. You have to be very careful not to get into the onions, though. I know where your coming from - the onions are the hardest thing to keep clean that we grow. We are sitting on 7000 sets now going on two weeks waiting for a break in the weather.

Tom

After several years of hand weeding onions, this year I put down some Preen before I planted the onions.

Almost two months later and very few, if any weeds. The bindweed pushed through, but it could grow through a sheet of metal, if you gave it time.

These onions were planted on March 7th in one of my high tunnels. I put out over 7000 onions this year, many times more than I have ever put out before. I was dreading the weeding, but the Preen is doing a great job. I will reapply in several weeks, as directed.

I planted the onions in this building on 40 plus inch beds, 4 rows. I planted them 1.5-2 inches apart. We pull every other onion for green onions, or smaller fresh onions. In another building we planted them the same distance, only 2 rows to a 30 inch bed. The outside rows are 3 rows to a 36 inch bed.

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I appreciate the suggestions, I think I may try a row of the plastic mulch, I will plant them 5 inches apart in all directions on a 36 in row of mulch wish me luck,...
If I get baseball size onions it should be interesting pulling them I am trying to picture planting in a quarter size hole and pulling thru the same hole...
Jay your onions look wonderful and did I say I had a lot to plant 7000 is not anything doable for me! I don't use weed killers of any kind because I grow on a small scale my niche is the organic side of things, Thanks for sharing your suggestions and pictures.
PitterPatter lets get atter...

i grow organically and find that i have to weed my onions at least once thoroughly then i mulch them with straw.

The cost of Preen for me is outrageous. I use granulated Treflan that I order from a couple farm supply companies/ Equity and FS here in IL. It costs $30 for a 40lb bag and goes a very long way. It works great. I believe Dixondale recommends it. I also give them a N boost with a little ammonium sulphate ($10 for a 50 lb bag).

Brook

I only used this on my onions. The big bottle cost $10 at a local store on sale. I thought it was well worth my time and money.

Jay

Watch puting too much ammonium sulfate into your onion patch if your growing sweet onions - sulfur is what makes onions hot and you cry when you cut them (hydrogen sulfide). Ammonium nitrate works well but you have to jump through hoops to get it. Treflan is what we use for pre-emergence control, too. Trifluralin (the generic ingredient name of Treflan) was the active ingredient of the original Preen. They make an organic Preen with corn gluten as the active ingredient but my understanding is that efficacy was is somewhat hit and miss. We tried straw mulch a couple years ago on a test patch and had a lot of neck rot problems. My gut feeling is that as the onions mature you need to pull the straw back from them so that they can dry down with out the straw holding in moisture.

On an interesting side note there is an old Amishman up here that grows Sweet Candies that are consistantly half again as big as a softball. His secret (aside from a dozen little Amish kids to weed) is lots of horse manure and water the snot out of them until the summer solstice then no more.

Tom

Ammonium sulphate also acidifies. I use it on my blueberries. I agree on the straw. I have used it with success on garlic. I really honestly don't use a lot of chemicals, but after losing whole crops to weeds and disease I had to do something---and it works!! I tried the corn gluten to absolutely no avail. In my small garden at home, I have great control over problems, but I simply can't do that on 5 acres. When I retire and can invest all my time to it, maybe I can. Also, the weed bank in my soil is immense, but every year I see improvements. Do any of you use fungicides on your onions??

Brook

Brook

Tom, where are you getting Poast? We haven't been able to find it.

All of you, be grateful that your area have fertilizer companies and such that are willing to talk to a vegetable grower. Around here, they just laugh at you and say they can't help you. Our greenhouse that should be able to get most anything, is only for the household size and not for the small commercial person.

Pitterpat, the Amish wait til most of the onions are mature, then they pull the plastic off of the onions, and then gather the onions up and finish drying them.

Marla

Brook - never used fungicides on the onions - I have been trying to get them pulled as soon as they start to droop and getting into the shed to cure. Sometimes the weather does not co-operate and the last couple of years actually had to dig them with a spading fork as the roots were too deep and tore the bottoms off an unacceptable number. On my list (you know the one as long as my arm) is to build an onion digger attachment for the tractor. We plant 6" centers on 12" rows so it has to be offset to the tractor but that's no big deal.

Marla - we got the Poast from FS. Dad's been dealing with them for years and had most of them in school along with their kids so they are pretty good about taking care of them. IIRC E&R also carries it (they are more over your way) but can not find their catalog off hand to see. It's a RUP so to get it you have to have your Private Applicator's tag but that's realy simple to get. A little secret is that there is a home based product that is the same as Poast called Hi-Yeild Grass Killer. It comes in small bottles (pints I think as opposed to the Poast which came in a 2.5 gallon jug) so the cost per sqft coverage is higher but if you don't need much you save off the big jug price. I have seen it at Rural King and Farm and Fleet - it is not restricted use.

Tom

Tom, I love my Rural King, I know many of the employees by name and sight, and they know me. Thanks so much, I've seen the Hi-Yield, but didn't think about it being home-based Poast.

Marla

I think that planter's paper would be better than plastic for onions. I used to use weed blocker on everything when I had a small garden and made little triangles for each onion seedling. A little mulch is ok for onions but not too much.

Jay, at $10 I'd buy Preen too. Here, I think an 8lb bottle is $24.

Brook

brookw, I think that you are thinking of aluminum sulfate as an acidifer not ammonium sulfate. No big deal, unless someone uses ammonium sulfate on their blueberries.

No, Luke, I meant what I said. When I first started growing blueberries, I used aluminum sulfate and lost a lot of them even tho' you frequently see it recommended. I then read about toxicity of aluminum and blueberries and switched. I've lost almost none since. Alum sulf is a great acidifier for other plants, but I keep it completely away from blueberries. Anyway, I acidify with elemental sulfur and if the plants yellow or show chlorosis, I give them a shot of iron. I think the product is called Copperas.

Brook

I thought about this idea in winter but it is too windy for me to try in my field:
Put down newspaper sheets and bury edges, then wet really well and poke the onions through the wet paper. Then sprinkle on some mulch to hold everything ok- just a little.