60-70 days. Black Beauty Zucchini Summer Squash Seeds.  Open Pollinated. AKA: Courgette. One of the most productive crops to ever find its way into the home garden, Black Beauty zucchini summer squash seeds will produce vigorously well up until the frost. Harvest Black Beauty zucchini often as fruits are most tender and delicious when about 6-8", but seeds quickly produce 18-24" long zucchini if left out in the garden even for a few extra days.