The ultimate guide to when to plant vegetables and why

Squash
Summer squash, such as zucchini, are best planted in late spring (May to June) to early summer (June to July). Winter squash, such as pumpkin, can be planted in late summer (July to August) for a fall harvest. Harvest summer squash when they are still young and tender, usually in mid to late summer (July to August). Harvest winter squash when the skin has hardened and can’t be easily punctured with a fingernail, usually in late fall (September to October).
Carrots
Carrots can be planted in early spring (March to April) or late summer (August to September), when the soil is cool. They grow best in well-drained soil and full sun. Harvest carrots when they have reached the desired size and color, usually around 60 to 80 days after planting, depending on the variety. For spring-planted carrots, harvest in late spring to early summer (May to June), and for late summer-planted carrots, harvest in late fall (October to November) or early winter.
Broccoli
Broccoli is a cool-season crop and can be planted in early spring (March to April) or late summer (August to September). It grows best in moderate temperatures and partial shade. Harvest broccoli when the heads are firm and compact, but before the yellow flowers open. This is usually around 60 to 80 days after planting. For spring-planted broccoli, harvest in late spring to early summer (May to June), and for late summer-planted broccoli, harvest in late fall (October to November) or early winter.