Soil temps down in the root zone are raised by a warm weather spell, yet still kept low due to cold rains, cold subsoil, short days, limited light intensity, etc. In another 10 days the soil temps will start rising dramatically, above the 50-degree mark. Right now your soil temps at 6 inches may still be in the mid 40-s, risky territory for many onions.

Here is a link that might be useful: cool soil temp graph / Massachusetts

That's an interesting graph planatus, thanks. It would be interesting to see one from this year to compare the changes that seem apparent in our climate. I do keep some records and one of note was the high temperature (air) didn't go above 50 till April 10 in 2003. Most years I'm looking at total snow melt in the last week of March. Of course this year we had no snow but to support what you are saying, my asparagus has not broke the surface yet so the soil temp is still low. I expect that to happen sometime this week with the currant 10 day weather forecast.

It's so nice to know there are other people around who actually like to think about soil temperature. My asparagus isn't showing yet, either. Maybe we can use it as an indicator plant for setting out onions?

I planted lots of onion seedlings and a few rows of shallot sets on March 14th. We then proceeded to have five days of record warmth. The new Vermont records are in some cases 20 degrees warmer than previous highs. Needless to say, things jumped out of my raised beds. My garlic is almost a foot high as of yesterday compared to last year when it was still covered with snow.

I know from experience these crops are quite hardy. However, I'm concerned that this enormous unprecendented early rapid growth will be severely damaged as temperatures have now moved toward normal.

Alright, you're killing me! How did it turn out? I have only gardened in northern MA for 10 years, and this season is my second in a new vegetable garden, so the weird winter is very hard to factor. My hardneck garlic Belarus (first year for that crop) was up by March, not sure how high, and did well, I think. Harvested in July, which seemed early but most scapes had bent. It tastes good. How did the warm/cold/hot season suit your onions and garlic?

Although we fell back into cold weather after planting I had the best yield ever. Fully expecting a lot of bolting that never occurred, in hindsight waiting till the temperature stabilities would have been a more prudent approach. All in all a great year for onions and a disaster for my apples.