How Soon Can You Plant Small Grains? Can You Plant Too Early?

February 19, 2024 /

Margaret A Smith, PhD
Forage Agronomist, Albert Lea Seed

Key points are boxed below.

How time flies! It was only a year ago we were asking, “When is it too late to plant small grains?” 

With the warm and balmy weather south of the Minnesota border, we’ve been receiving calls asking, “Can I plant oats now?” 

Enthusiasm is great, but please keep the drill in the shed—for now. We don’t know for certain how early you can plant spring oats, barley and wheat. While the conventionally accepted answer has been, “As early as you can get into the field,” I question that truism this year.  

The unknown wildcard factor is: Will air and soil temperatures continue to rise, as we usually see with a late March or early April planting in southern Minnesota and northern Iowa? The concern about ultra-early planting concerns whether or not there are prime conditions for planting—fit soils and warm days—followed by cold, wet weather. If seeds swell and start to germinate, then air and soil temperatures drop below optimum for continued growth and the seeds or seedlings may rot before temperatures are warm enough for the development of a functioning root system and crop emergence.  

Tables 1 and 2 below show the recommended optimum and last planting dates for small grains for six northern states. How much sooner we can go depends on predicted temperatures and your willingness to take on increased risk. For those farming outside this area, make adjustments to these dates based on your geography and long-term small grain planting trends. 

Table 1 – Optimum seeding dates and last recommended seeding dates for small grains in Minnesota

Area of Minnesota Optimum Seeding Date Last Planting Date
South of U.S. Highway 23 First week of April First week of May
South of MN Highway 210 Second week of April Second week of May
South of U.S. Highway 10 Third week of April Third week of May
South of U.S. Highway 2 Fourth week of April Fourth week of May
South of Canadian border First week of May First week of June

Source: University of Minnesota’s Late Planting Spring Small Grains

Table 2 – Recommended spring seeding dates for spring-seeded small grains in five northern states.

North Dakota (South) North Dakota (North) Nebraska Ohio Pennsylvania New York
Before May 15 Before April 30 March 15-April 1 Late March-Early April April 15-May 10 By April 15

Key Point: What is “Early Planting” for Small Grains in Your Area?

Not sure where you fall in these geographic ranges? The closest you can get to localizing these recommended dates for your farm is to use past experience on the farm and in your surrounding area. Your observations are important due to microclimatic differences, such as in the coulee regions of the Driftless Area in the Upper Midwest and near the Great Lakes.

What is a long term, early average planting day for small grains you or your neighbors grow? Perhaps not the earliest planting date you’ve ever experienced, but early! The optimum planting period for your farm is likely between that date and 7-10 days following. VERY early planting will be two to three weeks before the first date identified.

Growth of Cereal Grains

Spring-planted cereal grains are cool-season annuals that thrive in temperatures below 70o – 75oF. Minimum soil temperatures for germination of small grains are:

  • 35o – 37oF for spring wheat
  • 36oF for barley
  • 40oF for oats

Ideally, daytime air temperature highs would reach 60ºF and overnight temperatures would not drop below 40ºF for a great small grain stand within 8-10 days after planting. Fortunately, small grains are resilient through germination and emergence. Similar to corn, the growing point on small grains remains below the surface until the five-leaf stage. During seedling emergence, the plant growing point can survive temperatures down to at least 28ºF (and sometime lower). Oats planted on two farms in northern Iowa in late March 2023 withstood an extended wet, cold period in April and didn’t emerge for 30 days. After temperatures finally warmed, seedlings emerged and fields had excellent stands. 

Your Forecast

Check the 30-day forecast for your area. Though weather forecasts 45 days ahead are subject to change(!), they are the best we have to work with. Forecast temperatures for Albert Lea, Minnesota through March 26 predict almost all daytime temps above 32ºF and nighttime low temperatures consistently below freezing. Though February has been unseasonally warm, these March predictions are only slightly warmer than long-term temperature averages. Remember that these are air temperatures, not soil temperatures. Though you may be able to get into the field during this period to plant, these temperatures are less than ideal for rapid stand establishment. 

Keep watching your forecast and have equipment primed to go when soil conditions are good and temperatures three weeks out look favorable.  

Key Point: Early Planting Dates for 2024

In general, planting two weeks BEFORE traditional early planting dates (see tables above) for spring-planted small grains should be safe. Growth may be slower, but still progressing. Planting three to four weeks before the long- term average early-side-of-optimum dates, puts you at risk of rotted seeds and reduced stands.  

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