I'm trying to grow orchids. I can't find a book that tells me when and how to repot them.

I have some with roots on top of the pot. Is that the way they're supposed to be or is it time to repot?

Also, do I feed them when they are in bloom? I've got two books on orchids and neither answers those questions.

– Melba Dean, Fair Oaks

According to UC Master Gardener Bill Pierce, a great resource for your orchid questions is the Sacramento Orchid Society. Its website is http://sacramentoorchids. org. The group meets at 7 p.m. the first Wednesday of each month, except August, at Odd Fellows Hall, 1831 Howe Ave., Sacramento.

A comprehensive book that may help answer your questions is "Ortho's All About Orchids" (1999) from the Ortho Books gardening series. It contains information about transplanting, pot sizes, step-by-step instructions and photos. Copies are available via Amazon.com and other sources.

This book recommends that these plants be fed weekly – whether blooming or not – with a diluted (half strength) solution of plant food.

Meanwhile, here's some general information in response to your questions.

The new roots in orchids are usually very obvious – they often grow above the pot rim. You should repot the plant when the new roots are just beginning to appear.

Before repotting, water the orchid, then remove the plant from the pot. Clean the roots by pruning away rotted sections. Divide the plant if desired.

Choose a pot that will accommodate two years of new growth (that may be only an inch or two bigger than the former pot). Repot the plant with bark and support the plant with a stake if it appears to be top-heavy.

Mystery lily

Both Dracunculus vulgaris and other black calla-like lilies are near-black purple and smell pretty bad, but there's a big difference between them – mainly size.

C.J. Addington of Citrus Heights should know. He grows them in his garden. That prompted Addington to write in when he saw the photo of the mystery lily sent in by a West Sacramento reader.

"I grow Dracunculus in my own yard here in Citrus Heights, and that plant in the picture is most definitely not it," Addington wrote. "Dracunculus is a big, massive plant – sometimes over 3 feet tall – that makes a single huge bloom with a pungent dead animal scent."

Addington identified the mystery plant as Arum sintenisii (recently moved out from Arum orientale as a separate species).

"It is a much smaller, tuberous, clumping plant that has glossy arrow-shaped leaves," Addington wrote. "I also grow this plant in my yard, and if you see the two side by side, the difference could not be more obvious."

Arum sintenisii is hardy in this area and a reliable spring bloomer, he said. "The odor of the blooms is 'interesting' but relatively innocuous, not nearly as intense as other carrion flowers."

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