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Extension > Small Farms News > March 2016

Wednesday, March 23, 2016

Soil Temperatures Needed for Germination

Source: Beth Berlin, University of Minnesota Extension

We had a glimpse of an early spring, but then temperatures dipped back down to close to normal. Many gardeners were ready to get a jump start on their gardens when it was so warm in early March. Although the frost is out early this year, soils need to reach a specific temperature in order for seeds to germinate. Here is a list of common vegetables and the minimum and optimal soil temperatures for seed germination:

Crop                              Min. Temp (F)     Optimal Temp. (F)
Bean                                    60                          60-85
Beet                                     40                          50-85
Cabbage, Carrot,
Cauliflower                            40                          45-85
Corn                                     50                          60-95
Cucumber                             60                          60-95
Eggplant                               60                          75-95
Lettuce                                 35                          40-80
Pea                                      40                          40-75
Radish                                  40                          45-90
Squash, Watermelon,
Muskmelon                            60                          70-95

Recognize that even if the minimum temperature is met, it may delay the number of days until the seedling appears. For example according to research done by J. F. Harrington, University of CA at Davis, a carrot planted at one-half inch that germinated in 41°F soil took 51 days for the seedling to appear while only 17 days when the soil temperature was 50°F. 

Other crops such as tomato and peppers in a typical year need to be started indoors or purchased as a transplant due to the number of days to maturity.  Read your seed packets to know specifics for that variety. For example, some varieties of tomato mature in 57 days where others require 70 days or even longer.

To determine your soil temperatures, purchase a soil thermometer from a local vendor or online supplier.  Success using other types of temperature gauges, such as a meat thermometer has shown some success as long as the thermometer reads lower temps. For more information about gardening visit 

Increase the Competitiveness of Specialty Crops in Minnesota

4:00 pm CST on April 29, 2016 is the MDA’s deadline for Specialty Crop Block Grant Applications.

Specialty crops include most fruits & veggies, floral and nursery crops; see federal definition here:

MDA SCBG funding priorities:
  • Innovation in production, aggregation, processing, packaging
  • Improving operational efficiencies, reducing costs or other barriers, and increasing access to distribution systems and new markets for specialty crops
  • Increasing the demand-for and supply-of locally produced specialty crops
  • Pest and disease control, and varietal improvement
  • Practices that encourage conservation and environmental stewardship, including organic specialty crops research
  • Grant requests may range from $10,000 - $100,000.
  • Match is not required.
  • Indirect costs are not allowed.
  • Duration of projects may exceed two years.
Industry-wide benefit/Industry Support and extension of results are important, and grant administration/reporting are not to be taken lightly. For those reasons, we encourage collaborations that involve growers and industry organizations. USDA does not allow projects that benefit an individual farm, food business or other entity.

This SCBG competitive process requires you to apply online. Start today and chip-away; your changes will be saved in our MDA online grants module until you hit submit!

For more information:

The Specialty Crop Block Grant RFP and Grants Manual is published online here:

Questions? Contact Julianne LaClair, MDA Grants Specialist, 651-201-6135,

Friday, March 4, 2016

Tree and Shrub Pruning

Source: Nathan Winter, University of Minnesota Extension

Pruning trees and shrubs can be extremely beneficial to their health and beauty. Pruning trees during winter dormancy results in vigorous new growth in the spring, and can be used to eliminate branching problems the tree may have.

Apple trees, including flowering crabapples, mountain ash, hawthorns and shrub cotoneasters should be pruned in late winter from February to early April. Spring or summer pruning increases chances for infection and spread of the bacterial disease fireblight. Autumn or early winter pruning is more likely to result in drying and die-back at pruning sites. Oak trees, especially red oaks, should also be pruned before April to reduce their chance of developing oak wilt.

Pruning approaches include crown thinning, crown raising, and crown reduction. Crown thinning is primarily used in hardwoods to increase the amount of room for light and air to penetrate the tree. You still will want to maintain the trees natural shape, and form. Another form of crown thinning is to make sure there is only one dominant leader instead of two or more co-dominate leaders on the tree. This is the easiest to do while the tree is still young.

Crown raising is cutting off some of the bottom branches to permit travel underneath the tree. This could be for lawn mowers, people, and vehicles. Be sure not to raise the crown of the tree too high to avoid an excessively high crown. At least 50% of the tree’s height should be living crown.

Crown reduction is another approach to pruning. This method should be used only in a last resort when the tree has outgrown its permitted space. This approach should not be used on trees with a pyramidal growth form.

Topping and tipping pruning practices do more harm to trees than they help. Topping is pruning large upright branches between the nodes and is sometimes done to reduce the height of the tree. Tipping is pruning lateral branches between nodes to reduce the crown width. These practices result in sprouts and dead branches that will reduce the life of the tree. Use the crown reduction method as a last resort and avoid topping and tipping.

What about treating the wounds? Most of the time the tree sap, gums, and resins naturally work to decrease pathogens invading the trees. Therefore, there are very few circumstances when wound dressings are needed for pruning cuts. Often, they create more problems than they avoid. One scenario in which treating wounds is recommended is for oaks that are wounded between April and October. Remember; do not prune oaks between these months. Fresh wounds during that time attract the beetles that spread oak wilt, and leaves the trees very susceptible.

The University of Minnesota Extension Website contains a vast amount of information and can be found at the following link: Following is a great link to learn more about pruning trees and shrubs:
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