Well, the basic problem is that some may start to sprout in warm, moist soil. It depends on the variety, some are just quicker to do this than others. So, the safe thing to do is to dig them ASAP.

I gardened in SF clay for decades so I know what you're talking about. You cannot work California clay in January. That is the rainiest month, and right now you've gotten huge amounts of rain even for January. Wet clay should not and cannot be worked. I never planted anything in the ground (pots only) in December or January - the clay is too wet and too cold. A planter box should have purchased soil mix in it. Not clay. The comment about using plastic is to protect soil about to be planted in from getting excessively wet. Not for the whole yard. I would instruct my clients to tarp the area they wanted me to plant fruit trees in so it would be workable. Once clay is wet, you have to wait for it to drain a few days before you can work it. (Hence the tarping beforehand.) Squeeze a bit in your hand. If it squeezes through your fingers and remains in one piece with ribbons sticking out where it came through your fingers, it's too wet. It should crumble at least a little bit before you try to work it. When it's dry enough, compost is the best thing. Gypsum does not work in California clay. You will not transform it overnight, or even in a year or two. It will always be clay, and that's not a bad thing - I miss clay. Here I'm gardening in dirty gravel, with no water retention or nutrient retention or any measurable organic matter. Most trees and shrubs will grow in clay just fine, with annual additions of a little compost. Lettuce and other vegies are a different story, they need a looser soil. That's where mounding up amended soil comes in. Dig up the clay, add some compost and maybe some purchased topsoil, and mix it all together and heap it up above grade. Don't just lay stuff on top of the clay and then plant in it, as water will sit on top of the clay and the plants' roots will then be sitting in water. Mix it up so it grades from amended soil to the native clay. Compost helps any soil, clay or sand. You just can't work clay soil after all that rain you've gotten. You'll have to wait for it to dry a bit.

I believe Corn Gluten is considered an organic pre-emergence. Emergence meaning when the plant from seed can be seen above ground. Specifically what Corn Gluten does is attack the plant's rectal when the seed coat softens, opens and the stored energy within the seed begins growth by bringing the rectal into its escape route into your soil. Corn Gluten carries with it a low level organic nitrogen percentage that nurtures the existing plants while serving as a pre-emergence product. The cost of this and several chemical ways to do pre-emergence has always been debated. My opinion is that all ways of using pre-emergence tactics is only a relatively short time period of less that excellent control anyway. The chemical companies have always paid the universities to come up with warped facts to satisfy the use of their poisons. For instance as stated above: half life is a relatively short period of time but soil life comes out to be about a year. Few stop to read, think and question. First these chemicals are non-degradable. Half life I guess means only half of it has been flushed by rain or watering from your use point and is on its way to your rivers, bays and oceans. Full life must mean your soil is again void of the chemical. That is a direct statement that everything you put on is now en-route to the oceans of the world. The enormous poison pits and zones in the oceans are known and growing. There is no other place for them to go except to enter the evaporation facts and become even stronger where they are. Severe weather may lift them and redeposit them to complete the journey once again back to the ocean pits. If you use and love sea salt now how do you feel it will be enjoyed in another million years? Back to our soils now stated to be full life with no measurable poison in the soil. What they do not test and will not tell you is how long your natural biological recovery will take. The realistic recovery may be five years or longer. Is there a point of no return? I do not think anyone knows. No part of the answer to that question is very nice. Would growing the grass at four inches and mulching the cuttings make better sense? Would spot treatment in the early recovery make more sense than wholesale broadcast of some poison? Do we really need golf course picture perfect homestead grasses? Could we as homeowners recycle those leaves and plant tops by mulching open soil? Could legumes become cover crops that rejuvenate? I'm sure most could do some of these things to eliminate the use of some if not all man made chemicals. This reasoning and these questions apply to all man made non-biodegradable poison chemicals. All! There are no other statements possible that are absolutely true. How does all this relate to pre-emergence chemical concerns? Dumb question. 90% or more of those chemicals are non biodegradable.

Glad other folks don't go strictly by the "soil worked" statement. zeedman, I'm actually over 100 miles south of you. I'm pretty close to the bottom of Lake Michigan- I probably should have said so in my first post. So I'm not sure if that will make a difference or not with timing. And not anything to do with the conversation at hand, but I miss camping at High Cliff. forgotten- I didn't realize I could sprout my peas. I figured since they aren't supposed to like transplanting, that meant I couldn't sprout them either. I am so going to do this with some of my peas this year. How long do they take to sprout? I would be doing them in my 65 degreeish dining room where I have south facing windows for a little extra warm if the sun ever comes out again, lol. farmerdill- I didn't realize there were smooth and wrinkley peas. All of mine look kind of smooth like the Alaskas, so I think maybe I'm good with adverse conditions peas. My beds are pretty good draining- a mix of horse compost, leaves and grass clippings, and sandy loam that gets stirred up every spring, and put to bed with another layer of leaves in the fall. Some are raised beds, and others are lasagne beds, kind of like raised beds without the outside box because I heap them in deep.