How to Propagate Crocosmia From Seed

Crocosmia is a cheerful South African perennial flowering plant that grows from a bulb, or corm. It features bright red, yellow or orange blooms and attractive, pleated leaves. A relative of the iris, crocosmia grows to a height of 3 to 4 feet tall and excels in shrub borders, flower beds and as a background planting. The crocosmia lucifer, which features crimson blooms, is a popular variety. Although crocosmia are often planted from corms, it is not difficult to grow them from seeds, which you can harvest yourself from existing crocosmia plants.

Close-up image of the vibrant red, summer flowering Crocosmia (montbretia) Lucifer
credit: Jacky Parker Photography/Moment/GettyImages
How to Propagate Crocosmia From Seed

Collecting Crocosmia Seeds

If you have a crocosmia plant in your garden or you know someone who does, you can collect the seeds at the end of the growing season. Harvest the seeds when the seed pods on your crocosmia plants start turning brown and develop a papery texture and cracking tops. The seeds inside should be dry and brittle. Separate the seeds from the chaff and organic debris. Place the seeds in a brown paper bag, and store in a cool, dry place until you're ready to grow them.

Crocosmia often reseeds itself in warm climates, so you can grow new plants from seed without any effort. This hardy plant can even become invasive. Cut off seed pods before they can drop the seeds if your crocosmia is multiplying too rapidly to suit you. You can also share the beautiful blooms by collecting crocosmia seeds and giving them to other gardeners so they propagate their own plants.

Starting the Plants

Starting your seeds indoors helps the seedlings get started early so they're ready to transplant outdoors when the weather is right. Sow your crocosmia seeds in late winter in indoor seed trays. Place a 2-inch layer of seed-starting soil in the tray. Plant the seeds 1/4-inch deep, and spray the with a mister after planting to provide moisture without disturbing the seeds.

Place the seed tray in bright, indirect light. The seedlings grow best at temperatures of 60 to 70 degrees F. Water the trays regularly to keep the soil moist. You don't want to let the soil dry out, but you also don't want to let it become soggy or water-logged. Your crocosmia seeds should germinate within 2 to 3 weeks.

Transplanting the Flowers

When the outdoor conditions are right, it's time to transplant your seedlings into your garden. Transplant your crocosmia seedlings in late spring when they have 4 to 6 sets of true leaves. Choose a transplant site in full sun with rich, loose, well-drained soil and enough room to space your crocosmia seedlings at least 1 foot apart. A spot near a window is ideal so you can appreciate the hummingbirds it will attract.

Water the seedlings well after you transplant them. Continue to thoroughly water them twice a week while the seedlings become established and part of your crocosmia care routine. Mulch around the seedlings to conserve moisture. Fertilize your crocosmia plants after planting with a water-soluble fertilizer formulated for flowering perennials. Repeat fertilization in July when your crocosmia are blooming. Apply a deep layer of mulch in the late fall to protect corms in the ground from freezing and allow them to produce new underground growth during the winter.

Your seedlings will continue to grow throughout the season. In the fall, the seeds they produce can keep your crocosmia collection growing even larger.