Yes, you can plant zucchini late summer and get a great fall harvest if you live in a warm climate. You need at least 40 to 60 frost-free days left in your growing season for this to work. Many gardeners have success with July plantings that produce right up until the first hard freeze.
When I first tried a late July planting two years ago my spring zucchini plants had just been destroyed by squash vine borers. I tested whether a late start could still give me a harvest that year. Those late season plants produced better than any crop I'd grown before and kept giving me squash through mid October.
Fall zucchini planting works best when you count backwards from your area's first frost date. Subtract about 50 to 60 days for the plant to reach maturity and start producing fruit. This gives you the latest date you can plant and still expect a harvest before cold weather arrives.
University of Saskatchewan notes that your soil needs to stay between 59 to 64°F for zucchini seeds to sprout. Late summer soil is plenty warm for this so germination happens fast. Seeds often come up in less than a week when you plant in warm garden soil during July or August.
Late season zucchini plants face fewer pest problems than spring plantings in many areas. The squash vine borer lifecycle winds down by August so your young plants grow up without that major threat. Fewer bugs mean healthier plants and a cleaner harvest with less damage to deal with.
Purdue research shows zucchini plants stay at peak production for only 2 to 3 weeks before slowing down. This makes succession planting valuable if you want fresh squash all season long in your garden. A late summer planting picks up right when your spring plants start to fade out.
Protect your late summer seedlings from intense afternoon sun during their first two weeks in the ground. In my experience the heat can stress young plants and slow their growth even though zucchini loves warm weather. A simple shade cloth or cardboard shield gives them time to establish strong roots in your garden.
Water your late planting more often than spring crops since summer soil dries out faster. The combination of heat and nearby tree roots can pull moisture away from your new plants. Check soil moisture daily and give your seedlings a drink whenever the top inch feels dry to your touch.
Read the full article: When to Harvest Zucchini: Ultimate Guide
