Costus spectabilis (Fenzl) K.Schum.
Cadalvena spectabilis, Cadalvena dalzielii, Cadalvena pistiifolia, Costus pistiifolius, Kaempferia spectabilis
Bloom Time: Late spring to early winter
Costus spectabilis is a herbaceous perennial plant that produces four large fleshy leaves that lie flat on the ground and form a basal rosette. The leaves are glabrous above and pubescent below, especially along the midrib, and often have purple-pink margins. The inflorescence is terminal, growing from the center of the rosette. Flowers are showy, yellow, open singly and die rapidly but are immediately followed by another. This species becomes dormant during winter, shrinking to a centipede-like rhizome without roots.
USDA hardiness zone 8b to 10b: from 15 °F (−9.4 °C) to 40 °F (+4.4 °C).
How to Grow and Care
Costus fall into the tropical category, so if you do well with philodendrons and other tropical plants, you should be able to grow Costus without too much issue. They aren't terribly picky about their light, but the key to successful growth is lots of water and fertilizer to keep up with their heavy demands. If your plant starts to suffer from brown leaf margins, it most likely is being underwatered or exposed to cold drafts. Try to raise the humidity and increase the water. Costus are susceptible to mealybugs and aphids. Keep a careful eye on your plants, and inspect them to catch infestations early and treat them immediately. Severely infected plants should be discarded.
Depending on the species, you'll probably need to repot your Costus annually at the beginning of the growing season. If you want to keep it a manageable size, use this as an opportunity to divide the rhizome and refresh your potting soil, but keep it in the same size pot. Some larger species can grow to 10 feet (3 m) or more, so be aware of the potential size issue.
See more at How to Grow and Care for Costus.
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