First weekly vegetable update of 2025 - May 13, 2025

Authors: Natalie Hoidal & Marissa Schuh

We kick off our weekly updates during a record breaking early season heat spell and fires in the Northeastern part of the state. The dry weather has allowed for field prep and planting, but has made early season watering critical. More seasonable, cooler temperatures and some rain are on deck by the week’s end. 

General Notes

Soils are warming up

In Southern Minnesota soils are already above 65 degrees, meaning growers can comfortably plant sweet corn and green beans. Soils around Hutchinson and St. Cloud are in the low 60’s; soils in far Northwest Minnesota are still in the 50s. Check out soil temperatures for your area using the MDA Soil Temp Network Map.

Preparing for a hot summer

The National Oceanic and Atmospheric Administration’s three month forecast shows that we have equal chances of an above average vs. below average summer in terms of heat and precipitation, with slightly higher changes of below average precipitation in Western Minnesota. Despite the projection of a mostly average summer, this week was a good reminder to take heat safety seriously to keep yourself, your employees, volunteers, and farm visitors safe.

Image: NOAA seasonal temperature outlook


In 2024 we worked with PhD students in the University of Minnesota’s doctor of nursing practice program to develop guidelines for vegetable farmers for heat safety. This includes water intake recommendations as well as break recommendations for different types of farm activities as the weather becomes warmer and more humid. Consider printing these guidelines and keeping them posted at the farm. Click here for a printable PDF of the heat guidelines; we also have it available in Spanish, Swahili, and Hmong.

In addition to taking enough breaks and drinking enough water, make sure to give your crew time to adjust to hot weather. It takes our bodies time to adjust to heat, and so it’s important to follow “acclimatization” guidance with new employees or volunteers. The National Institute for Occupational Safety and Health (2018) provides the following recommendation:

For new workers, the schedule should be no more than a 20% exposure on day 1 and an increase of no more than 20% on each additional day. In an 8 hour work day, this means only about an hour and forty minutes in hot sun on the first day, a little over three hours the second day, etc.. Try to find jobs that people can do indoors or in the shade of they are starting work on a very hot day.

Final crop planning: have you planted enough to fulfill your contracts / goals?

While most farmers have completed their crop plans already, we’re still meeting plenty of folks who haven’t quite finished their plans for the season. Is your goal to have at least 30 pounds of tomatoes for your first farmers market? Or maybe it’s to deliver 300 pounds of broccoli to a local school on September 1? How do you make sure to plant enough to meet your goals without having too much of a surplus?


We’ve developed some new crop planning tools to help you estimate yields, figure out how many plants you need, and provide your plants with enough space to thrive. Check them out here.




Having enough produce to meet your market demands takes careful planning, even for farmers markets. Photo: Cat Dehdashti.

Terminating cover crops

It’s great to see so many healthy stands of cover crops on farms around the state. Most of these cover cropped fields will need to be terminated soon and prepped for planting, so it’s a great time to share this excellent resource from our partners in Indiana, all about cover crop termination strategies for small farms.

Cutworms

Looking at black cutworm trapping networks across the state, we have had the right weather conditions over the last month where there have been a couple drops of moths in many counties in Southern Minnesota. Moths that arrived in early April are in the stage of development where they are doing leaf edge feeding, and potentially cutting (the hot weather will make them grow and get big enough to cut faster). You can find information about cutworm management on the UMN Extension website.



Young cutworms making small holes in and on the edges of leaves. Photo: Bruce Potter, UMN.

Crop Updates

• Asparagus harvest is ongoing. We have heard from a couple of growers about bent spears. Early in the harvest window, a lot of this was likely due to weather (cold temps, high winds). Asparagus beetles are also out, and their feeding can damage the head of spears as well as cause bendy spears. Asparagus beetle management is tricky – sprays should be timed for peak beetle activity (warm, sunny afternoons) and products need a short pre-harvest interval. For example, in organic production, Entrust is labelled for asparagus beetle but has a 60 day PHI, meaning we can’t use it until we are done harvesting. For conventional growers, there are a couple of options, check the Midwest Vegetable Production Guide for information.
  

• Brassica planting continues. Across almost all of the state (excluding the NE), cabbage maggot has emerged or will emerge in the next few days. If you’ve had a history of this pest, either delay planting or use row covers to keep flies off of plants. For conventional growers, chlorpyrifos products with previously existing labels can use existing stock in accordance with those labels until June 30, 2025. The UMN field crops team has a good write-up of what is going on with this active ingredient.
  

• In cucurbits, high tunnel cucumbers are going out, field plantings are waiting for warmer weather. If you are interested in using trap crops for help with cucumber beetle management, remember those blue hubbard squash need to go out before your main planting. Plant them at least two weeks before your main cucurbit crop.
  

• High tunnel spring greens are wrapping up, making way for summer crops like tomatoes. We’ve had a lot of fun tasting some new (to us!) vegetables this spring like Tokyo Bekana and Komatsuna. One of the things we noticed when did the 100 farms project in 2023 was that so many high tunnels were sitting empty in the spring (and research has shown that farmers who use the shoulder seasons in their high tunnels are the most profitable). It’s great to see more farmers and more embracing spring greens. 
  

• Garlic is up. We’ve seen quite a bit of winter kill this year, or fields with really patchy survival. We are nearing the final days where we would recommend spring fertilizer applications, and many growers may already be past this point. Try to avoid fertilizing after your garlic has reached 4-6 inches, as too much nitrogen at this stage of development can hinder bulb growth. With last year being a big year for aster yellows, check for plants that are extra yellow and stunted, and remove them to reduce potential aster yellows later this growing season.
  

• For sweet corn, use soil temperature to pick when you plant. Check the soil temperature maps in your area and wait until temperatures get closer to 60°/65°F consistently to plant your sweet corn. Planting before the soil is warm enough will delay germination, increasing chances of root rots and making succession plantings all come up at the same time. Seedcorn maggot is flying across Minnesota, if you have a history of damage from this pest, have a protection measure in place for plantings going out.
  

• Tomatoes are in all different stages. High tunnel growers with supplemental heating have had their tomatoes planted for weeks, and others are just getting started. In case you haven't seen them yet, we have new nutrient management recommendations for high tunnel tomatoes!