Gardening successfully in Ohio depends on understanding the state’s dynamic seasonal changes. The climate creates distinct planting windows, making “what can I plant now” a matter of precise timing and selection. A thriving garden relies on matching a plant’s temperature needs to the current conditions, ensuring seeds and transplants establish themselves. This seasonal guide details planting from early spring through winter preparation.
Understanding Ohio’s Planting Windows
The growing season in Ohio is defined by two major climatic markers: the average last spring frost and the average first fall frost. The state spans USDA Hardiness Zones 5b through 7a, with most populated regions falling within the 6a and 6b zones. This variation means the last expected spring frost can occur anywhere from mid-April near Lake Erie to mid-May in the inland and northern areas, creating a difference in planting start dates.
Beyond air temperature, the soil temperature is the most important factor for seed germination and root establishment. Cool-season crops can begin sprouting when soil temperatures are as low as 40 to 45 degrees Fahrenheit. Conversely, warm-season vegetables will fail to germinate or suffer stunted growth if the soil temperature is not consistently above 60 degrees Fahrenheit, with some needing 75 degrees for ideal results. Gardeners must consult local frost data and use a soil thermometer to determine the current planting window.
Early Season Planting: Crops for Cool Soil
The first planting window opens as soon as the soil is workable, often in late March or early April, well before the last frost. These cool-season vegetables are resilient, able to withstand light frost and the temperature swings common to Ohio spring weather. These crops are harvested before the intense heat of summer causes them to “bolt,” or prematurely flower, which reduces flavor and quality.
Root vegetables such as radishes, beets, and carrots can be direct-seeded once the soil has thawed and drained sufficiently. Peas should also be direct-seeded in early spring, as their roots do not tolerate transplanting well. Leafy greens, including spinach, lettuce, and kale, thrive in cooler temperatures and can be planted in succession every two to three weeks for a continuous harvest until the weather warms.
For the Brassica family (cabbage, broccoli, and cauliflower), plant seedlings grown indoors four to six weeks before the last frost date. Setting out transplants gives these plants a head start to mature before the summer heat. In the flower garden, cold-tolerant annuals like pansies and violas can be planted early, as they handle temperatures slightly below freezing. Hellebores, or Lenten Roses, are an excellent choice for early color, as they are perennials that bloom even when snow is present.
Peak Season Planting: Warm Weather Vegetables and Flowers
The peak planting season begins once the danger of frost has passed, a point many Ohio gardeners mark around the Memorial Day holiday. This timing is important because these plants are sensitive to cold, needing both warm air and warm soil to thrive. Planting too early risks killing tender new growth and delaying the harvest.
Warm-season vegetables, including tomatoes, peppers, and eggplant, should only be planted as transplants once night-time temperatures remain above 50 degrees Fahrenheit. Corn and bush beans can be direct-seeded into the warm soil; corn requires an average soil temperature of at least 60 degrees to germinate. Vining crops like cucumbers, zucchini, and squashes also need this warmth and a long, frost-free period to produce a high yield.
For flowers, the peak season is the time to plant heat-loving annuals that provide continuous color until the first fall frost. Vibrant zinnias, petunias, and celosia are choices for sunny areas, as they tolerate the high summer temperatures and humidity common in Ohio. Impatiens and coleus are perfect for shadier spots, adding bright foliage and color where direct sunlight is limited. These summer annuals are purchased as transplants and set out in late May or early June.
Late Season Planting: Fall Harvest and Overwintering Preparation
The third distinct planting window is in mid-to-late summer, focusing on crops that mature during the cooler, shorter days of autumn. This involves planting a second round of cool-season vegetables from spring. Timing must be calculated based on the days to maturity relative to the average first fall frost. Planting kale, broccoli, or late-season carrots in July or August allows them to mature in the mild fall weather, often resulting in a sweeter flavor after a light frost.
Preparation for overwintering begins in the fall, when spring-blooming bulbs like tulips and daffodils must be planted. These bulbs require a period of cold dormancy (vernalization) to produce flowers, so they should be planted from late September through early December before the ground freezes. Another task is planting garlic cloves in late October, covering them with mulch so the bulbs can establish roots and sprout the following spring.
Once the main garden is harvested and cleared, cover crops can be sown to protect the soil over the winter. Cereal rye and oats are choices, as their dense root systems prevent erosion and suppress weeds. Legumes, such as hairy vetch, can also be planted to fix nitrogen in the soil, which benefits the next season’s crops. These cover crops are terminated and tilled into the soil in early spring to enrich the garden bed.