How to Propagate Hardy Perennial Hibiscus

Rose mallows have flowers as much as 10 to 12 inches across.

There are three kinds of hardy hibiscus grown in perennial gardens. Rose mallows (Hibiscus moscheutos) are the largest flowering perennials, according to Dr. William Welch of Texas A&M University. Rose mallows bloom from summer to frost and are hardy in U.S. Department of Agriculture Plant Hardiness Zones 4 to 9. They can be propagated by division in spring or fall, or by seed. If seed is started in very early spring, they will bloom the first year, which is unusual for a perennial. Confederate rose (H. mutabilis) is a shrub in Zones 9 and 10, but a perennial farther north. Propagate confederate rose by cuttings. Texas star hibiscus (H. coccineus) has large, single red flowers and should be propagated by division or seeds.

Things You'll Need

• For Division:
• Shovel or spade
• Organic material, such as compost
• Garden hose
• Pruners or strong knife
• For Seeds:
• Seeds
• Sterile seed starting mix
• Clean pot or other container
• For Cuttings:
• Pruners
• Damp sand or seed starting mix
• Rooting hormone (optional)

Instructions

Rooting Cuttings

1. Fill a bucket or large pot two-thirds full with sand or sterile seed starting mix. Water well so the material is uniformly moist.

2. Cut a 12- to 18-inch long piece from the end of the current year's growth. Take cuttings from rose mallows and confederate roses while in active growth. In areas where confederate roses grow as a shrub, take cuttings any time between spring and fall.

3. Remove all leaves from the bottom 6 to 9 inches of the stem. Cut remaining leaves in half. Remove any flower buds.

4. Dip the cut end of the stem into the rooting hormone. This step is optional but improves the chances that the stem will root successfully.

5. Insert the stem into the damp sand or seed starting mix, stopping 1 inch below the bottom remaining leaf. Firm the sand around the stem. You can root multiple cuttings in the same container; place them 6 inches apart.

6. Store the cuttings in a spot that remains cool but doesn't freeze. Check the container occasionally to make sure the rooting medium stays moist.

7. In spring, give the cuttings a slight tug. If you feel resistance, they have rooted and can be moved to individual containers or to a nursery bed in the garden.

Plant Division

1. Dig holes for the new divisions 12 inches deep and 24 inches wide. Amend the soil with organic material, if necessary. You can also plant the divisions into clean containers.

2. Dig up the hibiscus you want to divide. Wash as much soil as possible off the roots with a garden hose.

3. Inspect the roots. Prune off any broken or diseased roots.

4. Cut the root clump into three or four sections with the pruners or knife.

5. Place each division into its new home. Make sure the plant is situated so that the rootball sits no deeper than it did before. Backfill around the roots with soil, firming to remove air pockets. Water well to settle the plant.

Seed Starting

1. Sow seeds 10 to 14 weeks before the last expected spring frost. Soak seeds for right hours before planting.

2. Moisten the seed starting mix. It should be damp but not dripping.

3. Fill container to 1/4 inch from the top. Gently firm the mixture.

4. Place the seeds on top of the seed starting mixture. Cover with 1/4 inch of planting material. Water gently to settle the seeds.

5. Place the container in a warm, well-lighted area. Keep soil moist but not wet. Ensure that sprouted seedlings receive enough light that they don't lean or get leggy.

References

• Texas A&M University: Hardy Hibiscus
• North Carolina State University: Perennials: Hibiscus moscheutos
• University of Illinois Extension: Dividing Perennials
• Clemson University Cooperative Extension: Hibiscus
• Washington State University: Spokane county Extension: Seed Starting
• Burpee Seeds: Hibiscus: How to Sow