Late summer is a good time to start thinking about next spring in your flower gardens. Chores such as removing perennial weeds, refreshing the mulch, and trimming back spent flowers are all important to keep your flower garden under control and healthy. Another task is to decide what to do about flowers that like to self-sow. These are flowers that grow vigorously each year and then in summer drop a bunch of seeds that will overwinter and sprout next spring. This could be a good thing in the garden, depending on what you’re growing and what you want to grow next year. The first step is to know who the rampant self-sowers are and what to do to encourage them to multiply or to stop them from taking over.
Here are some common flowers that readily self-sow in the garden. To discourage them from dropping seeds, remove spent flower heads before they go to seed and cultivate the soil well next spring to kill any sprouts that germinate. If you want them to self-sow, leave the spent flower heads and next spring thin the new seedlings to a proper spacing so they aren’t overcrowded. Overcrowded seedlings will be tall and spindly and will have poor flowers.
Cleome: The spider flower loves to drop seeds all over the garden. If you want to avoid these seedlings, grow sterile seed varieties such as ‘Senorita Blanca’.
Calendula: It’s nice to see calendula sprouting up in the garden each spring, but remember that the offspring may not have the same flower color as the mother plant.
California Poppy: California poppies love to self-sow. They look beautiful, if you have the room for them, when they flower en masse. Although orange is the dominant color for California poppies, sometimes you’ll even get red or white versions popping up, too.
Anise Hyssop: Anise hyssop is a beautiful white, blue, or pink annual flower that self-sows readily. The varieties with blue flowers self-sow the most. To prevent this, grow ‘Blue Fortune’, which has sterile seeds.