You started conditioning your bales, but were interrupted by Mother Nature.  Snow, rain, cold, whatever has thrown a twist in your progress and you are now concerned that the bales will not be ready to plant on time.  Relax, and just pick up wherever you left off or were interrupted, and continue the process.  One tip for speeding up the process if you are concerned that the bales are not conditioning quickly enough for your planting schedule, is to cover the bales with some black plastic sheeting.  This will help adsorb heat energy from the sun and hold in the heat promoting the growth of bacteria in the bales. This isn’t required but can be helpful if you are on a strict schedule and need to plant on a particular date.

It is true that if the air temperature is cooler, the bacteria will not grow as quickly.  This is why we refrigerate our leftovers from dinner, or put stuff we want to preserve in the freezer.  When bacteria are cooled or frozen they will not reproduce as quickly and their effective rate of decomposition of any substrate will slow dramatically.  If the bales warm up to even a slightly higher than air temperature level, this means the bacteria are growing inside.  Bacteria reproduce by expanding to a certain size and then splitting.  During this magical splitting process, the cell will shake and vibrate and create friction, which raises the temperature inside the bales.  If the air temperature outside is 40 degrees but the temperature inside your bales is 45 degrees, this is a great sign of bacteria development.  If the air temperature is 75 then the inside of your bales may be 130 degrees or hotter.  The differential in temperature will increase as the air temperature increases.  Don’t expect too much if your bales are in the “refrigerator” or the “freezer” outside.  When the days get warmer the bacteria will grow quickly.  Plan to plant after you have been conditioning the bales for 12 days (when the temp is over 45 degrees).  If you get a few colder days, just add a couple more days to the c1129_thanksgiving-leftoversonditioning period, or cover with black plastic.  A sunny day will really get things cooking under that plastic.  It is NOT necessary for your bales to ever get HOT.  Sometimes they don’t get so hot, but they will always get warm.  If you measure the temp every day and the temp never goes above 80 or 90 degrees, don’t worry, they will be fine.  If you put your hand into the bales and they feel cold, don’t worry, if you followed the conditioning recipe then the bales are ready to plant after 12 days (18 days for the organic treatment), so plant or seed right away.  Don’t worry if it seems like the bales still look the same, they will not have changed much in appearance, but the bacteria will have grown and colonized much of the bale by then, so it is time to plant.


  1. Elaine Woodward

    Never done this before. Been watering for over a week. Added fertilizer. They told me urea instead of nitrogen. I have put urea in water x 2. There is something in an article about putting top soil on bales? Also, there is grass growing thru the top.

  2. If I go ahead and plant and my bales start to heat up later, won’t that harm or kill the plants? My straw bales have not heated up at all. I started conditioning about 4 weeks ago. Last year they hit over 100 degrees. Our spring temperatures have been all over the place from 35 degree nights to 85 degree days so it has stayed cold or hot for only a couple days at a time. Are there any other causes for this delay I should address besides weather?

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