Soil Temps & Planting Dates

A few weeks ago Kendal wrote about some of the variables farmers have to deal with during the first part of planting season, especially in a drawn out winter that just seems to never end. Putting your right foot forward is important to secure a great starting point for your crop and yield potentials. Kendal mentioned soil temps, hybrid selection (excellent vigor/emergence), watching heavy residue and late season frosts that can all tie into yield make or break. I am going to touch on the soil temps/planting dates. Both aid in a good stand going forward into the growing season.


Soil temps and planting dates work with each other in certain ways, but again do they? Most everyone knows that you can have the best plan at the end of March on how you are going to attack the spring planting come April, but Mother Nature sometimes has other plans for us. We know that it is important to be timely on planting dates for the maximum yield potential but planting too early can also be hurtful to yield. At this time, the weather has yet to let up on winter with temps staying around the 35-40 degree mark during the day range here in southern Iowa to a lot less north of here.


The soil temps for planting need to be at the 50-degree mark and for a couple of days following planting for good germination. Its important to keep seed out of a cool, wet or snowy soil. 


Here are a few other ideas to check out on your own soils to determine if you are close to your window opening:

1. Look ahead at the forecast to insure a cold snap isn’t coming to cause soil temps to drop. 2. Check soil temps for the past 5 to 7 days and do a physical test with a thermometer (4″ deep after day break). If soils temps are not at the correct temp or are expected to drop, it might be a good idea to postpone your planting, no matter what the date is.


Early planting can boost yields but it is no guarantee that it will make or break your yields come fall. Delayed planting dates cannot determine lower yields by itself. When delayed planting occurs, from cold or wet conditions, most of the time warmer soil conditions are just around the corner to help get that optimal stand we are looking for.


Mark Johnson

Iowa Regional Agronomist