Then this is proof that large sugar concentrations in soil are in fact detrimental to some plants, both in low and high soil temps. I wonder what the optimum amount is for the growth of microbial life.
It's very confusing to me. @Meadowlark's onion failure goes against everything I know about what happens with the use of molasses. About one once per gallon of water per week is not a lot of molasses as I use basically the same amount except on a bi-weekly basis when I use 2 onces. All of my plants thrive but then I don't usually have a garden going in the winter either. When I killed the nutsedge (and there was a LOT of it) it took about 4 months. I would apply 1 1/2 CUPS per gallon of water normally every 2 weeks. The area was about 30'x40' and I used over 3 gallons of molasses during the process. When the nutsedge was gone I planted green beans in the area and had a good crop. Maybe, perhaps, onions don't like carbohydrates? The only variable I can think of is the volume of the molasses/water mix poured onto the plants. There is much more to be learned from this.
Agree, it certainly surprised me. There was a very high moisture content in the soil just prior to the big temp drop. Maybe the effect was similar to adding salt to your ice cream maker to lower the freezing point.
Probably so, as sugar lowers the freezing point of water also. Onions have a high carbohydrate/sugar content naturally but would adding that amount of sugar change the freezing point? I cannot believe it would do so. I am more of the opinion that something else caused the failure although I can't imagine what it could be unless the seedlings were still very small at the time of the 15 degree weather and were possibly larger during the freeze 2 years ago.
It all depends on how much organic matter is already there and one cannot have too much organic matter in his soil. Sugars do not break down the organic matter, the soil microbes do. And yes, sugars are a feed source for the microbes which helps them to multiply and the more microbes there are the faster organic matter is broken down and therefore there are more nutrients available to plants.
All I can say is that I start applying molasses when I put my seedlings into the ground and I water my seeds in with molasses water. And I don't put molasses into my compost, I just throw in all of my stale beer and soft drinks. I should add molasses but it costs money and I am too cheap. It is just a guess but I would think cold weather would slow down the growth numbers of microbes just as warmth increases it. It wouldn't hurt anything to add sugars during cold weather but I don't know how helpful it would be either.
fluid oz. I use a little shot glass. I've got a 2 gallon watering can and I put molasses, maybe some liquid fertilizer, maybe some liquid humate, everything liquid I think the plants might need and give each plant about a quart and then water it in. And about once a month I will give each plant a little dry pelleted fertilizer and water it in with molasses. I try to keep everything on a 2 week basis. I probably use too much fertilizer but I have some really nice soil for this part of the country and fertilizer here is fairly inexpensive.
I am thinking of inground tomatoes now. I pour randomly about 1 quart around the base out to the drip line per plant. My tomato plants are on average about 3 feet in diameter so this would be about 7 sq ft per quart/plant or 28 sq ft per gallon and then this is well watered in. So, over a season of 4 months this would be about 8 quarts of liquid or 2 oz of molasses per plant. I grow my peppers in fabric containers so I use about 1/2 as much liquid. I do nothing scientific, just eyeball measurements except I do measure how much of anything I put into my watering can. As I said before, molasses does absolutely nothing for the actual plant, it only benefits the soil. So, since no two soils are identical no two formulas will be exactly the same. When I add molasses to my okra, corn, beans etc. I use a hose end sprayer set at 2 oz per gallon and water until water stands. This is probably more liquid than I put on the tomatoes but it seems to work fine. I have been doing this for years and it seems to have a cumulative effect as my garden soil is MUCH MUCH softer and arable than the surrounding soil although I do add leaf mold, compost and dried leaves each year.