I know from experience that allium can be allelopathic toward some legumes, specifically, pisum. The effect from perennial walking onion on spring-planted peas has been very pronounced, such that occasionally some pea-plants have been a near-total loss. However, the peas have to be quite near the root-zone of the onions, and if the onions are pulled a few weeks or months before planting peas there doesn't seem to be any problem. Annually-grown onions are quite unlikely to be a problem, since peas are planted well before started onions are set out and it would be months before the onion roots would be robust enough to exude serious quantities of whatever it is that the peas don't like, and of course by then peas are pretty much gone by. That's why most gardeners never have encountered this mis-companionship. I suspect that in the days when walking onions were quite common the conflict was well known, and the tale still gets told though tradition has changed.

Sharon: THANK YOU FOR THOSE FANTASTIC PICTURES !! I also did red-cabbage test today Sat. 7/25/20. Distilled water boiled in red cabbage is actually acidic according to on-line info. "Pure distilled water should be neutral with a pH of 7, but because it absorbs carbon dioxide from the atmosphere, it's actually slightly acidic with a pH of 5.8." From your pictures above, the grayish blue solution is alkaline with pH 7.5. My pH 7.7 clay is a bit bluer (tested by Earth Corp. soil testing company). Black, gray, or clear solution is neutral pH .. means it's a fantastic buffer (good for plants). I tested COMPOSTED grass clippings and it's clear water above black solution. Buffer is great to neutralize the acidity of rain. Clay buffers better than sand/loamy soil, but the best buffer is composted organic matter. Coffee is also a buffer (at first pinkish, but after 20 min., it's a clear solution). COMPOSTED plant-matter is very alkaline and neutralizes acidic rain well. COMPOSTED leaves decompose to alkaline pH, when I stuffed a bunch of leaves in LOAMY & fluffy soil .. the next year that got converted into HARD CLAY, very alkaline. Green grass clippings stay fluffy longer (more nitrogen & more acidic). Brown leaves are considered "carbon" in a compost pile, and decompose to alkaline pH & hard like clay. My tap-water in red-cabbage is VERY BLUE, it's at pH 9 as stated on village's website. I also tested baking soda and it's more blue than my tap-water. I tested paver's sand or yellow coarse sand, and it's slightly alkaline. I tested composted manure and it's very alkaline (from the lime added to deodorize and kill weeds in the bag). The pH of composted manure is just as alkaline as my clay at pH 7.7. Your LAST pic. is slightly acidic. Rain-water is even more acidic & reddish purple. Rain water here is pH 4.5. I also tested some drops of vinegar and it's fuchsia red around pH 3. All my rooting-soil for cuttings are black or clear solution at neutral pH (they have lots of yellow sand or vermiculite mixed in). The clay taken from diseased & black spotted roses are slightly acidic, rather than blue like my pH 7.7 clay. I had tested 5 different roses with black spots in the past, and the soil taken from the root level is pinkish in red-cabbage juice. It's either acidic rain can't drain well from that spot, or else there's NOT enough buffer to neutralize the heavy rain going down.

I've done it with one of the landscape cloth type mulches. It really kept the weeds down and I was really happy with that part of it. I watered with soaker hoses laid down on top of the landscape fabric (which also had a couple of inches of old hay on top of it), with one hose in between every two rows of onions. It worked well enough. At harvest time, you either have to cut the holes in the mulch material larger so you can pull the onions out through the holes (my holes were just X's cut in the mulching material, or lift the whole sheet of mulch so you can pull the onions. You still have to deal with weeds that pop up directly beside the onions, but that's nothing compared to how many winter seeds, in particular, sprout in newly planted onion beds. Bruce Frasier wrote about using plastic mulching long ago in one of the Dixondale newsletters, and if he says it can be done successfully, then it can be done. I think lots of commercial growers do it. I only did it for a handful of years. I found that I prefer to use a pre-emergent (corn gluten meal) at planting time and then just hand-weed what little bit of weeds sprout. By the time the pre-emergent is losing its effectiveness, my onions have made some good growth and I just put another layer of mulch on. My first later of mulch is usually about a half-inch of compost. Then I put on about an inch of old, spoiled hay. Then, as the onions enlarge, I add a layer of grass clippings. If the mulch thins out or weeds stop popping through, I add more mulch. I like using organic matter more than plastic because the organic matter decomposes and enriches the soil. Having said that, though, there's certainly nothing wrong with using plastic mulch. It works fine. I am not sure how well it would work in a very wet year. Since I have heavy clay, I always worried that the plastic might hold in too much moisture in a wet year, but we don't often have wet years here at our place, so I worried for nothing. I did love how the mulching material reduced erosion. I garden on a slope. There is not much flat land in my garden at all, so erosion can be an issue and the plastic certainly prevented much of that from happening.

Shaer, If you go to the Dixondale Farms website page I've linked at the bottom of the page, you can read about their trench method of fertilizing. I usually work fertilizer into the soil before planting because I want it down deeper in the bed below the root zone of the early plants, but I also use their trench method some years. The trench method can be used with any form of organic fertilizer or synthetic fertilizer. I like Dixondale's own fertilizer for use at planting time, although I don't buy it every year. I usually buy it and use it every other year. In the in-between years, I add lots and lots of organic matter in the fall and winter before planting onions in either February or March. I have clay soil that is mineral-rich, so mostly all I have to worry about is adding organic matter to improve its tilth and texture. With any kind of manure, even if it has been composted and even if it is from animals that people swear have never been fed any sort of feed that could be contaminated with herbicide residue, you still need to do a bio-assay test for herbicide residue. There is a specific type of herbicide commonly used on hay fields, pastures, and in city parks and golf courses that can persist even in the manure of animals long after they've eaten food raised with that herbicide sprayed on it. If it contaminates your garden seed, it can kill your crops and make your soil virtually unusable (except for corn and other monocots) for 1 to 4 or 5 years. Google "killer compost" or "herbicide carryover in manure or compost" to read about this long-term, ongoing issue that has been a problem throughout the 2000s if it is new to you. A couple of years ago, purchased, bagged compost killed gardens in a particular area, and the herbicide residue eventually was tracked back to name-brand horse feed that your or I or anyone else could walk in to a feed store and buy today. That's why we need to test all manure before we add it to our gardens----there is no guarantee that our animal feed wasn't contaminated with herbicide residue. A neighbor of ours inadvertently ruined her own garden a few years back by using manure from her animals and/or purchased hay as mulch. I don't believe she uses those herbicides on her place, but it was during drought years when ranchers were scrambling to buy hay from somebody....anybody.....in order to have something for their horses and cows to eat. I think that during that time, those herbicide residues were brought onto her place in purchased hay and then came into her garden either via hay mulch or animal manure. Rather than waiting for a unknown number of years for the soil to clear up, she decided to build a new garden in a new area----a workable option for folks on rural acreage who have lots of space, but not for someone on a standard city lot. You also can make manure or compost tea and feed it to the plants. That is another way to use clean, herbicide-free manure in a manner that won't burn plant roots. You dilute the manure tea after you make it until its color is the color of weak, watered-down iced tea. There are a couple of plants that are such heavy feeders that it can be hard to keep them happy---onions are sort of that way. They will devour any and all nitrogen you give them, and that's a good thing because lots of nitrogen makes lots of onions. With onions, the more nitrogen, the merrier. The number of leaves each onion plant has and the size of the leaves is what determines how big or small (along with rainfall) your onions will be. For big, softball-sized onions, your plants need regular access to plenty of nitrogen and roughly 21" of rainfall/irrigation during the plants' lives. With most plants, we urge folks not to overfeed nitrogen, but with onions, if you want big onions, shoot for producing big leaves and plenty of them. Each leaf gives you a layer or ring of onion flesh. Big leaves give you big thick rings or layers, small leaves give you smaller rings or layers. Early in their lives, I like the fertilizers that have more of a 1-2-1 ratio (like Dixondale's) to get the onions off to a good start. Then, a few weeks later, I like to give them some extra nitrogen to help the leaves make great growth. Having said that, sometimes I don't feed them at all and let them make all their growth merely of what is in my soil, but I do enrich the soil with copious amounts of compost every year. I often use Espoma's organic fertilizers, though I find myself not as happy as before with some that have been reformulated in recent years. Hope this helps, and feel free to ask more questions. Dawn Dixondale Farms' Onion Fertilizer Trench Technique