Now that you have selected a site for your garden and understand basic soil needs, it is time to decide what to plant. Some plants, such as tomatoes, peppers, and eggplants, require a longer time to mature. These plants can be started indoors or purchased at greenhouses and gardening centers as bedding plants.
Purchasing plants is a convenient way to get the vegetables you want to grow in your garden, but the plant variety you can choose from may be limited. For instance, if you want to plant a specific heritage variety of tomato, you may have to grow the plant from seed. Any plants started indoors or kept indoors for a long period of time must be hardened off before planting. Hardening off acclimates plants to the outdoors by slowly exposing them to outdoor conditions. It is usually accomplished by repeatedly moving the bedding plants inside and outside to exposing them to various amounts of sun and wind. For more information on moving seedlings outdoors, visit the UM Extension website.
Other plants can mature during the Minnesota growing season and are best sown directly into the soil. Seeds for these plants can be purchased from seed catalogs, garden centers, greenhouses and any other retailer that carries them. Root vegetables, such as carrots, beets parsnips, and radishes, can be sown into the ground as soon as the soil is warm enough to germinate, or sprout, the seed and the danger of hard frost has passed. The same is true for green leafy vegetables, such as lettuce and spinach, and legumes, such as beans and peas. Most vegetable seeds will germinate if the soil is 65 and 85°F. While germination may occur at cooler temperatures, the best success rates occur in this optimal temperature range. Since each vegetable has an ideal germination temperature, detailed information by plant type is available from the University of California Cooperative Extension.
When to plant the garden is another important decision. If you plant too early you risk the danger of frost, while if you plant too late your plants have less time to mature. The Minnesota Department of Natural Resources collects information about the average last freeze date in spring and first freeze date in fall for certain locations throughout the state. Based on the information for Detroit Lakes, if you plant on May 20, there is a 20% chance for the temperature to go below 32 degrees Fahrenheit, and if you plant on May 27, the risk reduces to 10%.
This does not mean you cannot plant sooner than theses listed dates. If you want to extend the growing season by planting earlier, you can cover your garden with blankets or ground tarps if there is danger of frost. A five-gallon bucket turned upside down on a tomato plant is a great way to protect it from frost.
There are also other ways to protect your plants if you plant your garden early. High tunnels are frames covered by plastic that can be up to 8 feet tall and 12 feet wide. They are designed to protect plants and provide the gardener room to walk. Cold frames are smaller, do not cost as much, and can be very useful for the home gardener. They consist of an unheated box with a cover of transparent material, which traps heat in the box and warms the soil up earlier. This means you can plant seeds in the cold box sooner than you normally would, and achieve better germination. This works especially well for crops that grow better in cool temperatures, such as kale, lettuce, and broccoli.
Sources for this article include:
- University of Minnesota Extension, starting seeds indoors: https://extension.umn.edu/planting-and-growing-guides/starting-seeds-indoors
- University of California Cooperative Extension, germination temperatures by vegetable type: http://sacmg.ucanr.edu/files/164220.pdf
- Minnesota Department of Natural Resource, Final Spring/First Fall Freeze & Frost Date Probabilities: https://www.dnr.state.mn.us/climate/summaries_and_publications/freeze_date.html
- Berlin, Beth. Extension Educator-Horticulture, University of Minnesota Extension, starting your gardens early: https://local.extension.umn.edu/local/benton/county-horticulture-educator/article/starting-your-gardens-early-1
More master gardener tips
According to the Becker County Master Gardeners, April is the time to...
- Have your soil tested if you plan to start a new flower or vegetable garden, or if one you have is not performing well. University of Minnesota’ Soil Testing Lab will analyze the soil and make recommendations based on reliable data. Stop by the Extension Office to pick up a soil testing bag and information sheet.
- Plant bare root trees and shrubs.
Repair lawn; reseed dead patches, dog spots and winter injury. Rake in lawn seed, do not fertilize until after first mowing.
Hose winter dirt off evergreen shrubs and trees if we haven’t had an early spring rain.
Plant pansies, violas and Johnny jump-ups outdoors late this month or early next, to enjoy them as soon as possible and for the longest time. They thrive in cool weather, but rarely hold up once summer temperatures soar. Dead-head faded flowers to promote best blooming.
Also, if you have not done so already, late March or early April is your last chance to ...
Start your seeds indoors under fluorescent lights. Check seed packets to see how many weeks ahead of transplanting they must be started.
Cut slender branches of pussy willow, Nanking cherry or red maple to force into bloom indoors. Re-cut the stems and soak them in a warm (not hot) water bath overnight, then in a bucket of warm water in a 60 to 65 degree location with indirect light. Move them to brighter light as flower buds open.
Repot houseplants before spring growth starts and you are busy outside.
Start new houseplants from tip shoot slips for new houseplants or to add to container plantings in May.
Prune trees, summer blooming shrubs, fruit trees and roses. If your oak trees need trimming, do it now to help prevent the spread of oak wilt disease.
Master gardeners, local library to co-host April 9 event
Local master gardeners will be setting up information stations at the Detroit Lakes Public Library on Friday, April 9, sharing tips about seed starting.
This program is offered free of charge, and will include stops at stations dedicated to making a newspaper pot, creating your own recycled container station and starting seeds in plastic deli containers and making a self-watering container out of a soda bottle.
All are welcome to tour the stations, which will be available at the Detroit Lakes Public Library, 1000 Washington Ave., between 9 a.m.-5:30 p.m.