Beginner Gardening: Why does marigold crowded by alyssum seem much happier?, 0 by RosemaryA

RosemaryA wrote:
My landlord planted a bunch of purchased marigold plants around the garden. One of them was planted where I had already sown some alyssum seeds but they hadn't sprouted yet.

Most of the marigolds have grown very little (only about 15 cm tall), have few flowers, and seem to be struggling, but the marigold surrounded by alyssum is 10 times as big (in terms of volume), about 25 cm tall, and loaded with blooms.

I would have expected the opposite, that the marigold crowded by alyssum would be having more difficulty because of the competition.

Here is the happy marigold: