Growing a successful edible garden involves timing. Sowing the right seeds at the right time makes optimum use of space and allows you to stagger your harvest. But before choosing your seed packets and eagerly planting your plot, remember that soil temperature is critical to seed germination. If seeds are planted in soil that is too cool, you'll lose both money and precious growing time. So for June planting, match your region's average soil temperatures with the vegetables best suited to those conditions.
Late-maturing vegetables sown in June in cooler climates will not be ready for harvest until late fall. So get a jump on things by purchasing plant starts for these varieties. Gardeners who live in warm climates can sow those same seeds straight into the ground in early spring. Just because a seed doesn't fall onto your climate's list for June doesn't mean you can't plant it; you just need to do so at a different time.
Hardiness Zones: Why They Matter
Hardiness zones or growing zones are a standard developed by the U.S. Department of Agriculture for gardeners to use to determine which plants will thrive in their location. Hardiness zones can generally point gardeners to the best time of year to get seeds or seedlings into the ground based on the average ground and ambient temperatures and sun exposure.
Hardiness measures the coldest temperature in the region, with the scale ranging from 1 (the coldest) to 13 (the hottest). A majority of the U.S. lies in zones 3 through 9. Knowing your plant hardiness zone will help you understand how cold it gets where you live and if it is too cold for your plants to survive.
Zones 2 and 3
Zones 2 and 3 encompass Alaska, North Central U.S., Northern New England, and the Rockies. Some think it's an exercise in futility to grow vegetables in these areas, but certain hardy plants do well in cool climates. When everyone else's arugula and lettuces have gone to seed, gardeners in the north are planting a second crop for season-long salads.
In June, plant root vegetables like radishes, carrots, beets, and potatoes so their sprouts appear after the last frost (which can happen in mid-June in high mountain regions). Hardy plants like peas, scallions, kale, and chard also do well sown straight into the ground.
Zones 4 and 5
By June, summer temperatures should be in full swing in zones 4 and 5 of the Northern Midwest and Southern New England. However, you can still get away with sowing hardy greens like chard, kale, and some lettuces (though certain types of lettuce may go to seed if the temperature climbs too high). All root vegetables, like carrots, beets, and parsnips, will do well sown in June. Carrots and parsnips can even withstand a little snowfall in late autumn to set their sweetness before harvest. Sow your second radish crop at this time, too.
Squash (zucchini and summer squash), beans, cucumbers, melons, and pumpkins can all be planted in early summer. Hope for an Indian summer for a bountiful harvest. And if summer decides to cut itself short, throw a frost cover over any remaining plants with fruit to protect your harvest a little longer.
Zones 6 and 7
These zones, the Pacific Northwest, Midwest, and mid-Atlantic, have some of the best climates for seed germination (and good soil to boot). Since seeds and seedlings love water and need to be constantly hydrated—almost soaked—to sprout, the mild June rains in the Pacific Northwest are perfect.
Pumpkin, squash, and zucchini seedlings love the moist soil and with the days growing warmer and sunnier into June, this will allow the plants to proliferate. Beets, carrots, parsnips, and potatoes will also benefit from June planting. But don't plant them too soon in a rainy climate or they may rot before they flower.
Zones 8 to 10
Some crops may have peaked by June in sunny California and the southern United States, which are zones 8 to 10. While New Englanders are just starting to see a variety of veggies on their plates, Californians are eating nothing but homegrown vegetables. Sowing in warm climates in what seems to be full-bore summer can be tricky. Just inland, you need to rinse to provide enough water for seeds to sprout. But coastal Californians can use the reprieve of the marine layer to help with sprouting. Try tomatoes, melons, corn, and okra in zones 8 through 10 in June, but cover seeds with row cover to keep them from drying out.
Southerners can plant a second crop of peas, plant sweet potatoes, and begin clearing out areas for fall planting.
Zones 11 to 13
Most climates in zones 11 to 13 including the islands of tropical Hawaii enjoy fresh produce year-round. Like the continental south, Hawaiians are reaping their gardens' bounty in June, however, beans, corn, watermelon, and tomatoes do well from seed in June. If you live there, practice succession planting (planting one crop after another in the same space). Make sure to rotate your crops based on soil nutrient needs so you don't deplete your soil.
Vegetable Garden Calendar. University of Georgia Extension