Hardy through U.S. Department of Agriculture Zone 4 and known botanically as Hibiscus coccineaus and H. moscheutos, these hardy cousins of the well-known tropical hibiscus are native to North America. Also called swamp mallow or rose mallow, these hardy perennials die down to the roots in winter and re-grow the following spring.
They are one of the last perennials to begin growing in spring, so be patient and don't give up on them. hibiscus powder They will begin to sprout about the time you are planting your peppers and eggplants, after the soil is completely warmed up.
They grow best in sites too wet for most other plants, one of the reasons for their common name "swamp mallow. "
Hardy hibiscus have much larger flowers than their cousins, H. rosa-sinensis. They can grow to the size of dinner plates in ideal sites, and usually reach at least 6 to 8 inches across regardless of growing conditions.
Propagate them using stem cuttings, which are cuttings taken from the still-tender new growth in late spring. Take the cuttings by midsummer, so the newly rooted plants have time during the growing season to become established before freezing weather sets in. Start more cuttings than you think you need; they have a relatively high mortality rate.
To propagate hardy hibiscus with stem cuttings:
Fill a shallow pan with vermiculite. Water it well, so the vermiculite is thoroughly moist but not saturated.
Cut off the tips of branches on a healthy hardy hibiscus, making the cut right below the third set of leaves. Remove the lowest set of leaves on the resulting cutting.
Push the eraser end of a pencil into the vermiculite to prepare holes for the cuttings. This will keep the vermiculite from pushing off the rooting hormone when you insert the cutting into the hole.
Dip the end of the cuttings into powdered rooting hormone. Blow off the excess.
Insert the cuttings into the holes in the vermiculite. Firm it around the stem of the cuttings so they stand up by themselves.
Put the pan of cuttings into a large plastic bag but do not seal the opening. Put the pan, inside of the bag, in a sheltered location in the shade.
Check the cuttings daily. If condensation forms on the inside of the bag, open the bag or remove the pan of cuttings from the bag. Water the vermiculite as needed to keep it moist but not wet.
Check for the formation of roots after 3 to 4 weeks. If the cutting resists coming out of the vermiculite when you gently pull on it, roots have formed. Let the cuttings continue to grow their roots until six weeks after you first started them.
Remove the cuttings from the vermiculite when they are six weeks old and plant in individual pots or into a nursery bed.
Plant hardy hibiscus cuttings in their final location in your yard the following spring, after the soil has warmed up completely, about the time you are planting your squash and melons.