Answer: There are several explanations for this. It is possible that you have planted two different types of cosmos or that the growing conditions are slightly different -- the nonbloomer may be in a cooler or shadier location or growing in a richer soil. In any case, they will most likely bloom eventually. Since the plants are growing well and since excess nitrogen can encourage more foliage and delay blooming, do not be tempted to use extra fertilizer to make the plants bloom. Unfortunately, all I can suggest is patience.
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