Self seeding plants, a blessing or a curse?
Without planning and proper management, a rampant self seeding plant can definitely be a curse in your garden. But there are ways to deal with prolific volunteers
Consider first your garden style. If it is manicured and restrained, self sowers are probably not a good idea. Perhaps you could consider transforming your gardens to a more informal look or cottage garden, where masses and random self sown flowers are suitable.
Plan a cutting garden. Self seeding annual and perennial blooms will not drop seed if you consistently cut blooms for indoor fresh arrangements.
Deadhead, deadhead, deadhead! Remove blooms as soon as they are spent and fading before developed seeds drop.
Hula Hoe! Cultivate around and between plants periodically to cut off seedlings at the root and bury them.
Try new varieties of plants that have been hybridized to minimize seed production or are bred to be sterile.
Using self seeding plants in less than ideal environments will reduce blooming, but will of course also reduce seed production.
Whatever you choose to keep aggressive seeders reigned in, they are generally preferred to plants that spread by rhizomes or underground runners. Those can be very difficult to contain.
Choose wisely, manage carefully, or just let them have there way with your garden bed.