Annual flowers that return each year through self-sowing

Sweet alyssum
By planting annual flowers in your garden, you can set a theme using the same flower varieties and colors each year, or create different garden themes by choosing different flower varieties and colors each year, or do a mixture of both by exchanging, adding, or reducing the number of flower varieties or colors. It's no wonder flower gardeners appreciate annual flowers when you think about the ability to set a new garden theme each year, plus annual flowers have a longer bloom cycle than perennial flowers.

The flower seeds of some annual flowers can be harvested for planting in the garden the following spring. But the exciting part is, when the flower seeds are allowed to mature and drop in the garden, if conditions are right, those flower seeds will produce new plant growth the following spring. This perpetuating new life the following spring in a process called naturalize.

Which Annuals Will Self-Sow?

Some annuals flowers are better at self-sowing than other annuals, perhaps because their seed is easily "harvested" by the movement of wind and watering. These annual flowers will usually self-sow:
  • cornflower
  • dusty miller
  • four-o'clock
  • impatiens
  • marigold
  • morning glory
  • petunia
  • spider flower
  • sweet alyssum
  • viola
Impatiens self-seeded, growing in cracks at the bottom of a step.

Optimal Conditions for Self-Sowing

I purposely do not mulch next to annuals to give them dirt near to the "mother" plant for seeds to drop. That's not to say that the seeds won't settle beyond the plant because seeds can flitter in the air, be carried by birds, bees, or a trouser leg, or float on excess water, taking shelter against any object that gets in their way. I've found viola growing five feet from where the mother plant had been, which was also through a picket fence to a landing spot in the grass. It's quite a sight to see a lone viola growing in the grass.

For the best success at getting annual flowers to self-sow, plant the flowers in rich soil and do not deadhead the flowers, or at least stop deadheading by the end of July. To create sticking power for the seeds, when you water the flowers, be sure to moisten the ground between the flowers. When the flower's seeds have matured, you can shake the flower on a near windless day to encourage the seeds to drop near the mother plant. Or, to keep with the self-sowing concept, let nature take its course, allowing the seeds (and pod or casing if applicable) to fall where they may. The flower seeds will become set in the ground, waiting for the cold of winter to continue their metamorphosis into new seedlings in the spring.