What to Plant in July in Zone 3

Count backward from mid-September before you sow anything new

With your first frost typically landing around mid-September, any fall crop sown this month has somewhere between 60 and 75 days to finish before that date arrives. Check the days-to-maturity number on the packet and subtract it from that count. A 55 day fall lettuce sown early in the month still leaves a full week of buffer against an early frost.

Kale, collards, and the fall brassicas on this month's list all fall inside that window comfortably, while a full head cabbage rated at 80 days does not, and belongs under cover instead of open ground if planted this late.

Keep the summer harvest moving so the plants keep producing

Bush beans, cucumbers, and summer squash all slow production noticeably once 3 or more fruits sit on the vine unharvested at a time. Pick every 2 days through the peak of the season, even fruit that looks slightly undersized, to keep the plant sending energy into new flowers instead of ripening what is already there.

Shade the seed row until it germinates

Soil surface temperature in full summer sun regularly exceeds 90 degrees here, hot enough to stall germination on fall lettuce and spinach seed entirely. Lay a board over a freshly seeded row for the first 3 to 4 days, checking daily, and pull it the moment you see the first sprouts push through.