Our trick for getting Beans to sprout early

We got off to a good start this year, with our first plants actually making it into the ground in March.  Here in Colorado, while there are plenty of days for shorts and t-shirts we can still get a good snowstorm or a deep freeze in April.  This makes it difficult to plant things by seed because the soil temperature can vary quite a bit from year to year.

We were proud of getting some pole beans in the ground on April 4 of this year, and were looking forward to seeing vines in May.   The soil temperature was 58 degrees, which is a bit below the low end threshold of 60 degrees, but we thought "close enough".  It had been beautiful out for more than a week, and the forecast for the upcoming week was warm too - with lows in the 50s.  

Before planting, we soaked the beans (seeds that is) in water, and then rolled the beans in Inoculant.  This is a naturally occurring bacteria that aid growth of plants and add to the soil fertility.  Here's one on Amazon for beans.  I don't know much on the subject, but it certainly worked last year when we had 100% germination in both our purple and green pole beans.  We put some carrots in the foreground of the beans, and thought to ourselves that those should sprout no problem because they are a cold-weather plant for sure.

After a week, however, there were no signs of sprouts in either the carrots or the beans.  We thought that maybe it just wasn't quite there in temperature, but the upcoming week would produce.  At the end of that week, however, we started to wonder whether we were going to have to replant.  It's always a tough call to tell when you have waited too long.  Still, we are way earlier this season than in many of our other seasons.

But, I had this idea to help things along, just in case.  I speculated that by putting clear plastic down over the soil, we would send the water evaporating back down in the soil, and the plastic layer would also trap heat to warm the soil for germination.    It was pretty simple to lay out, and we used some old plant markers to pin it down.

Sure enough, within 7 days, most of the beans have sprouted.  We had to take the plastic off tonight before they all sprouted because we didn't want the weight of the plastic on the seedlings that have now come up, and were concerned about burning the first leaves with the heat trapped under the plastic.

 You can see the condensation under the plastic.

 The first beans poking out, with plastic lifted

I looked before posting to see if this was a common practice that I just stumbled into, or if this was a genuine discovery.  I didn't find any pages in my brief search, but you can post them in the comments section if you find them.  I did find lots of pages about starting seeds in plastic bags, so if you think about it, this isn't much different.  It certainly solved our dilemma.