Although it may seem that vegetable gardens have just begun growing well and planting is done, it’s time to seed crops for fall harvest in July, and early August. Crops that require sixty days until maturity, and which are planted in July will mature in September as weather is cooling.
Look at seed packets and note the days to harvest. Count back from the first fall frost date, for example October 11th for the Denver area. With cool season vegetables, note that many tolerate the first light frosts of fall very well, and an extended harvest period can be anticipated. Warm season vegetables, on the other hand, must be planted to mature well before frost when temperatures remain warm.
Here are some vegetable planting suggestions with their typical number of days to harvest. Cool season vegetables include: peas (65), cabbage (85), collards (55), broccoli (65), kale (60), spinach (40), lettuce (60) and endive (45). Some root vegetable planting days to maturity are: beets (60), carrots (70) and turnips (50) days. These can be planted in July for a fall harvest. Even some fruiting vegetables such as bush beans (60) and cucumbers (55), can be planted if put in by mid-July. The very short season radish (30) can be planted in August for harvesting success.
Note that peas planted for fall harvest are prone to powdery mildew, so try to choose powdery mildew resistant varieties. Also, be sure to trellis or support them, so that air circulation will curtail disease. Sometimes harvest is less in fall, when compared to spring plantings.
Planting fall crops in “succession” where other spring crops have been harvested, is a way to extend harvest past the first frost and thereby maximize yields.