I planted a pot of flowers on the balcony, and I heard that earthworms are a good thing, so how can

You're right, if there are earthworms in the pot, it's very beneficial for the growth of the flower. If you want earthworms to be in a pot, you need to dig a few earthworms in the wild and bring them back to keep them in the pot. The earthworms newly placed in the pot should be observed often to see if they have settled down, otherwise the earthworms should be re-dug to replenish.

Then go dig for earthworms.

Earthworms are nocturnal animals that live in mud burrows during the day.

In the burrow, it goes out at night, generally from 8 p.m. to about 4 a.m. in summer and autumn, and its feeding and mating are carried out in dark conditions.

Location: Next to the well, at the bottom of the firewood and straw stack and near [the best of the depression], by the road after the rain, it is also a good place, the field and vegetable garden are fertile, and the soil is collected with a shovel, and then there is a shop that sells fishing gear, specializing in fishing.

Of course, you have to use humus or loose soil, where earthworms live, first of all, your potting soil must be qualified, like hard loess on the side of the road, no matter how deep you dig there is no earthworm, that is not where it can live, so the focus is on what soil you use, the nutritious soil bought online can raise earthworms, dig one in the field and throw it into it to live, generally live in the place of black soil and humus, urban green belt also, that is brought by the transplantation of horticultural merchants, occasionally crawl out of the big earthworm in the morning, and directly pick up the ready-made.

That's not easy, go grab one.