I have been given some Hibiscus plants called swamp mallow, (Hibiscus sabdariffa) which grow well in my garden (just north of Toronto). I have both red and white varieties, some with both on the same plant root ball. The plants grow best during hot weather and have shoots up to 6 feet. The large beautiful flowers 8-12 inches in diameter last only a day or two. I have noticed that there have been fewer red flowers each summer, leaving me with only white blooms on most plants.
Is there a reson for the loss of the reds?
What fertilizer/nutrients are best for this hibiscus?
Attempts to grow from seed have been disappointing, as germination and growth is slow and new plants do not survive the first winter. Seed pods develop only during the hottest part of summer and we had little of that in the last year. Division of the root ball seems to work best.
Your comments and suggestions would be appreciated.