Zones 5 and 6 cover the upper Midwest through the mid-Atlantic — Ohio, Indiana, Illinois, Pennsylvania, and much of the Pacific Northwest. Average minimum winter temperatures are -20°F to -10°F (zone 5) and -10°F to 0°F (zone 6). With four-season potential, gardeners who plan ahead can harvest every month of the year. Zone 5 average last spring frost: May 15. Zone 6: April 15. Zone 5 first fall frost: October 1-15; zone 6: October 15-31. These are averages — your location may vary 2-3 weeks based on elevation and local geography.
Spring Planting Calendar
8-10 weeks before last frost: start tomatoes, peppers, eggplant, and leeks indoors. 6-8 weeks before: start broccoli, cauliflower, and cabbage indoors. 4 weeks before: direct sow peas, spinach, arugula, and lettuce (all tolerate frost to 28°F). 2 weeks before: transplant brassicas outdoors under row cover; direct sow beets, carrots, and Swiss chard. At last frost: transplant tomatoes with protection, direct sow beans, and transplant peppers after soil reaches 60°F.
Summer Variety Selection
Zones 5 and 6 suit all warm-season crops. Key varieties: tomatoes — Early Girl (57 days) and Celebrity (70 days) for reliability; Brandywine for flavor in a full zone 6 season. Peppers — California Wonder and Keystone Resistant Giant; zone 6 can ripen Ancho and Poblano. Cucumbers — Marketmore 76 and Straight Eight. Sweet corn — Ambrosia and Peaches and Cream; direct sow after last frost when soil reaches 60°F.
Fall and Winter Potential
By planning a second calendar around your fall frost date, you can harvest well into November and beyond. Start broccoli, kale, and Brussels sprouts 8 weeks before fall frost. Direct sow spinach, arugula, and lettuce 6 weeks before fall frost — these overwinter under row cover in zone 6. Plant garlic 4 weeks before fall frost for next summer's harvest. Cold-hardy kale and spinach continue producing under N-50 row cover through November in zone 5 and December in zone 6. A cold frame or low tunnel extends zone 5 harvests into December and enables true four-season production in zone 6.
Frequently Asked Questions
- What is the difference between zone 5a and 5b?
- Sub-zones represent 5°F within the main zone. For annual vegetables, use your actual recorded frost dates rather than sub-zones for planning.
- Can I grow sweet potatoes in zone 5 or 6?
- Zone 6 yes, zone 5 marginally. Use black plastic mulch, plant slips after soil reaches 65°F, and choose Georgia Jet (90 days). Results are inconsistent in cool zone 5 summers.
- When should I plant garlic?
- Zone 5: mid-October. Zone 6: late October to early November. Plant 6 weeks before your expected hard freeze, mulch with 3-4 inches of straw, and choose hardneck varieties.
- What should I succession plant?
- Lettuce every 2-3 weeks from early spring through July (then again in August for fall), radishes every 2 weeks April through September, and beans every 3 weeks from last frost through July. The long zone 5-6 season fits 3-5 successions of quick-maturing crops.