By Karen Johnson, University of Minnesota Extension
Have you put much thought into your garden yet this year? Now is a great time to take a soil sample, consider plant placement within the garden, and to get started planting some of the cool season germinating vegetables.
Do you know what the nutrient levels are in your garden? If not, how can you create the best growing environment for your plants? The University of Minnesota Extension has a soil testing lab that can help you understand your specific nutrients available in the soil and provide suggestions on how to improve the soil so you can grow healthy plants. Home gardens can get a basic garden soil test for $17 which provides the estimated soil texture, organic matter, phosphorus, potassium, pH, and lime requirements. The test includes an interpretation of the results and recommendations for your specific garden. For information on how to submit a soil sample, please visit soiltest.cfans.umn.edu.
Each year, a critical component to be successful is knowing your plant families for crop rotation and avoiding continuous disease or virus issues in your gardens. Many diseases and pests will impact multiple crops in the same family.
Here is a breakdown of many popular garden crop families:
- Apiaceae: Carrot, parsnip, parsley, celery, celeriac, dill, chervil, cilantro, and fennel
- Asteraceae: Sunflower, lettuce, endive, escarole, Jerusalem artichoke, artichoke, chamomile, tarragon, and echinacea
- Brassicaceae: Cabbage, broccoli, cauliflower, Brussel sprouts, kohlrabi, turnips, radish, kale, collards, rutabaga, watercress, horseradish, and bok-choi
- Chenopodiaceae: Beet, Swiss chard, and spinach
- Cucurbitacea: Cucumbers, melons, squash, pumpkins, and gourds
- Fabaceae: Beans, peas, cow peas, and lentil
- Lamiaceae: Basil, lavender, marjoram, oregano, rosemary, sage, thyme, and mint
- Liliaceae: Onion, scallions, garlic, leeks, shallot, chive, and asparagus
- Poaceae: Corn, sorghum, and small grains
- Solanaceae: Peppers, tomatoes, potatoes, and eggplant
Try grouping your garden by families to make crop rotation from year to year easier. Crop rotation helps to break the continuous issues with disease or virus affecting your vegetables.
Once you know the nutrient levels in your soil and where the ideal spot is to plant each vegetable family, consider getting a start with some of your cool season germinating vegetables. Vegetables such as peas, lettuce, radish, beets, and carrots will germinate in soil temperatures as low as 35-40°F. Here is a helpful chart with a list of common vegetable crops and their seed germination minimum and optimal temperatures:
Min. Temp (F)
Optimal Temp. (F)
Cabbage, Carrot, Cauliflower
Pumpkin, Squash, Watermelon
Although seeds will germinate at the minimum temperatures indicated, the rate at which they will grow and emerge out of the ground is much slower until the optimal soil temperatures are met. Keep in mind vegetable plants like the tomato and pepper typically have longer days to maturity and are best purchased as a transplant or started indoors in Minnesota.
Getting your soil sampled, understanding vegetable families, and planting cool season germinating plants, are all great ways to start this year’s gardening season!