Northern gardens are characterized by short growing seasons, mild summers and harsh winters. This is because most of the northern part of the United States falls between USDA hardiness zones 1 and 5. Temperatures in zone 1 during winter may fall as low as minus 50 degrees F, while zone 5 temperatures can drop to minus 10. Because of this, most gardeners are somewhat limited in their choice of plants to grow. One of the keys to successful gardening in northern climates is to select the correct vegetables and plant them at the right time.
Consult the USDA plant hardiness zone map to determine your hardiness zone. Most garden plants available for purchase have hardiness ratings for specific zones Plants such as tomatoes that are not hardy to northern temperate zones may only grow between the first and last frost dates in your area. Cool-season vegetables such as carrots will grow after the year's first frost.
Learn the first and last average frost dates for your area. You can start seeds as early as two weeks before your last frost date. Grow tender bedding plants after the last average frost date of the year.
Break up the soil in your garden to a depth of 8 inches with a rototiller as soon as the ground thaws. If the soil is wet, wait for it to dry and then break it up. All soil types can benefit from an application of organic materials such as compost or peat moss. Spread soil amendments over your soil to a depth of 4 inches and mix them with the soil using the rototiller. Pick out any stones, sticks and debris.
Select early-bearing hybrids of warm-season bedding plants to ensure a good crop of vegetables before the first frost date of fall for your region. Cold-hardy plants such as tomato, radish or lettuce will grow well from seed and continue after the first frost of fall.
Use a rake to dig furrows for your seeds. Plant your seeds twice as deep as their diameter. Cover with soil and water until the ground is as damp as a wrung-out sponge.
Plant bedding plants by digging a hole twice as large but no deeper than the plant's root ball. Tender plants may be started in the ground early by placing a floating row cover over the ground to add warmth for 48 hours. Then plant bedding plants, covering each with soil and the row cover to maintain warmth in the evening, at night and on cool days.
Check your plants daily and water whenever they appear dry. Your soil should remain as damp as a wrung-out sponge.