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4 early-planting factors to consider

Chris Torres soil temperature measurement
STRAIGHT FROM THE KITCHEN: Look in a kitchen cabinet, grab a meat thermometer and check your soil temperature before planting.
Look at your weather history, check your soil temperature and check on early-planting dates with your crop insurance agent.

Are you ready to plant? This past week’s beautiful weather might have you itching to get your planter into the field, even if it’s only a few acres of corn or soybeans.  

Can you argue against the idea of getting corn or soybeans in the ground earlier? The crop will mature earlier, you’ll be able to harvest it earlier, and you’ll be able to get fall work done earlier. Hard to argue against, especially when prices are as high as they are.

But remember, spring is unpredictable. Look at last year. It was beautiful, dry and warm in the beginning of April, only to feel like winter by the time the month ended. It was cold, rainy and, yes, even snowy in some places.

The official forecast from the National Weather Service is for a warmer, wetter spring. But short of having a magic crystal ball, we can only guess what Mother Nature has up her sleeve.

Here’s four things you should consider before planting early:

1. Look at your weather history. “The way I tell people is look at your historic weather patterns for 10 years, or at the least, five years, to see your historic weather extreme,” says Gaurav Goyal, regional territory agronomist for Bayer Crop Sciences in the Finger Lakes.

Remember that the ideal soil temperature for corn and soybeans is 50 degrees F. Anything less for a prolonged period can result in cold injury. Cold temperatures and rain, especially in the first 48 hours after planting, can lead to seed inhibition — when cold water rushing into the seed to rehydrate the cells ruptures them, leading to swollen kernels, aborted roots and chilling injury.

2. Check soil temperature. Measuring soil temperature is as easy as just getting a kitchen meat thermometer and sticking it in the ground a few inches, says Eric Rosenbaum, owner of Rosetree Consulting in Shillington, Pa.

“Then I stick it in the soil for three to four minutes before reading it," he says. "If I do that three times, I have a pretty good idea of what the soil temperature is."

If possible, try to sample in the afternoon.

“To get an accurate measure on their own, sample 4 inches deep at 1 p.m., keeping in mind the nighttime temp dictates temperatures, and this can change rapidly," says Del Voight, Penn State Extension agronomist. "Soil types and amount of residue all come into play, so this can vary across the field management zones."

Or, take soil tests at different times to get an average.

“Generally you take the soil temperature at planting depth,” says Jeff Graybill, a Penn State Extension agronomist. “So for corn, that would be 2 inches deep. Some folks say to take it midmorning. Another way to get an average would be to do it in the morning and again in the late afternoon and average the two. Soils under fodder will be cooler, and so if you have uneven fodder, you would take some temps under fodder and in some bare spots to get an average.”

Syngenta’s GreenCast tool measures current soil temperature down to 4 inches, the 24-hour soil temperature average and the five-day average soil temp. Just enter your zip code, and you’ll instantly get some useful data.


Cornell’s Network for Environment and Weather Applications estimates soil temperatures across the Northeast down to 2 inches. It’s just an estimator that’s based on current and historic weather conditions, but it still can be useful.

If you farm in Michigan, you can get soil temperature data from the National Weather Service’s North Central River Forecast Center. Just click on a location, and you’ll get close to real-time soil temp data, based on sensors at depths of 2, 4, 8, 20 and 40 inches.


3. Check your crop insurance. If you plan on going in early, check your crop insurance policy or call your crop insurance agent and ask what the early-plant date is for your crop. Anything planted before the early-plant date won’t be eligible for replant payments.

Also, look at historic planting dates for your area and try to get planting within that time frame. Historic planting dates can vary greatly.

In Pennsylvania, for example, the optimum corn planting date varies from April 15 to May 1 in the southeast part of the state, to May 15 to 25 in the state’s Northern Tier and Laurel Highlands.

“I have seen time and time again that if you’re planting corn a day or two after optimal planting date, you’re losing yield,” Goyal says.

Even worse, though, is planting in less-than-optimal conditions and having to replant because you lose seed or the early-planted crop dies.

“It’s better to plant in better conditions rather than rush it along to hit optimal planting,” Goyal says.

The bottom line is, don’t rush it.

4. If you must replant. Check your crop insurance policy first as this will play a big role in a replanting decision. If a crop is damaged by too much rain, frost or something else, the crop insurance agent must decide whether it’s eligible for a replant payment.

Most farmers have multiple corn and soybean varieties with varying maturities to manage risk.

If you plan on changing hybrids, make sure there’s enough growing degree days left in the season to accommodate the hybrid. Cornell’s Climate Smart Farming has a Growing Degree Calculator that keeps track of accumulated growing degree days based on weather conditions.

“Before replanting, you need to decide and see, do you have enough GDUs based on a five-year or 10-year average? That's the first thing to look at," Goyal says. "Also, think about other factors when you're changing product. How much yield will you lose by changing products."

Soybeans are a little tricky.

“On soybeans, you don't want to go too short on maturity here; you need longer maturity for vegetative growth," Goyal says. "It needs vegetative growth before reproduction season hits, and then daylight starts changing and the plant comes hard.

"Let's say you come into June and you want to switch the relative maturity from 3.0 to now 2.0 because you have a shorter season left. Well, the problem with that is now that it is 2.0 relative maturity, it's not going to grow as much into the vegetative state.

“So maybe go a little lower, but not too low that you will have such a small plant that you won't have much more to produce flowers on,” he adds.

More information on early plantings can be found at and

Good luck with planting!

TAGS: Planting
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