Some annuals are such reliable self-seeders they can pretty much hold their own with their perennial counterparts. They are usually wild meadow flowers, a little rugged but relentless in the propagation of their species.

I still find tall bell flowers from two years ago, blooming where I never planted them, and weedy little sprouts like the French mallows in the picture, whose seed heads, 'cheeses' as they are called, produce more than enough seed to populate the entire northern hemisphere. A third generation of Spider flowers reigns supreme over an entire flowerbed after it elbowed out the competition over the course of two summers.

I still find calendulas from seven years ago as well as the occasional snapdragon, stripped of the hybrid characteristics of the original cultivar and donning the more classic features of its parentage.

The vegetable garden surprises me every year with marigolds, and the flower borders with love-in-a-mist and moss roses.

Heirloom varieties are more likely to self-sow and they usually come true from seed.

Author's Bio: 

Main Areas: Garden Writing; Sustainable Gardening; Homegrown Harvest
Published Books: “Terra Two”; “Generations”; "The Plant - A Steampunk Story"; "Letters to Lelia"; "Fair"; "Door Number Eight"; "A Year and A Day"; "Möbius' Code"; "Between Mirrors"; "The Blue Rose Manuscript"
Career Focus: Author; Consummate Gardener;
Affiliation: All Year Garden; The Weekly Gardener; Francis Rosenfeld's Blog

I started blogging in 2010, to share the joy of growing all things green and the beauty of the garden through the seasons. Two garden blogs were born: allyeargarden.com and theweeklygardener.com, a periodical that followed it one year later. I wanted to assemble an informal compendium of the things I learned from my grandfather, wonderful books, educational websites, and my own experience, in the hope that other people might use it in their own gardening practice.