Geseneriad Petrocosmea

For those of you that are not familiar with Petrocosmea here is what the judge's manual of the American Glozina And Gesneriad Society has to say about Petrocosmea.

Petrocosmea: Asian genus with sometimes very flat rosettes of white-haired leaves. Most flowers resemble Saintpaulia. Most species have purple/lavender flowers, but P. kerrii has white and yellow flowers. The species with flat rosettes produce offsets tightly clustered around the crown. The bloom usually occurs from these offsets, so it is not advisable to remove them.

Petrocosmea Our Fury Friend

The following article is one that Linda Golubski handed out at a workshop she presented, at a convention I attended.

In 1990, I brought a marvelous (in my eyes) miniature sinninnigia 'Super Orange' on the plane with me to the Boston Convention. I KNEW it would win best in class or maybe even best other gesneriad. I walked into the showroom after judging and all I had was a blue ribbon. Sitting next to my "perfect" sinninnigia was this plant-miniature in size. It looked like a violet, covered with white hairs - IT HAD MITES! It's center was so tight and it had these dark purple flowers, one per stalk just standing straight up over the foliage. Surely, classification wouldn't have allowed a violet with mites in the show in a gesneriad class, would they? I investigated and found out that it was Petrocosmea flaccida and that it came from China.

That was all it took. It was love at first sight! I don't even remember who it belonged to, but I had to have one. It took me a year and half before I found one. My first petrocosmea came from Marcia Belisle. Every time I took it to a show everyone was fascinated with it - deep purple flowers, white hairs and perfect symmetry. What a must for a gesneriad lover!

I now grow 14 varieties and have been growing them for 14 years. There were no instructions on how to grow them when I started so it was strictly trial and error. I'd like to share some of my experiences with you.

I grow all my petrocosmeas exactly the same way as I grow my African violets. I use the same soil, fertilizer, light and wicking. I grow them on reservoirs and my humidity is between 60% and 70%. My temperature is about 68 degrees at night and about 74 degrees in the daytime. Now here are some specifics that I have learned. Petrocosmeas have shallow root systems, so I grow them in 5" pan pots or saucers with holes drilled in them for drainage. Some varieties like P. flaccida and P. forestii do not like to be repotted. They have been known to sulk for month's before they start growing again. When I repot my petrocosmeas, I over pot them with and inch or two of soil between the edge of the plant and the rim of the pot. The leaves creep along the soil surface without rotting. If you use this method, watch the leaves when they get to the rim and gently lift the leaves over the edge of the pot so that they don't curl under and inwards.

The tops of the plants like to be about 10" to 12" from the lights. Petrocosmea forestii absolutely does not like to get its leaves wet! They will turn gray, twist and die. And even though they are fury and look "petable", they don't like to be petted. We once had a lady at a show that picked up P. flaccida at a show and would not stop petting it. We finally had to ask her to either purchase it or set it back on the table because there soon wouldn't be any leaves left!

Another useful piece of information is that you need to be gentle when brushing. If you brush too vigorously you will probably get brown spots on the leaves.

Petrocosmea forestii is the most prolific. I've had as many as 50 blossoms on one plant in a 5" pan pot. Petrocosmea minor with it's shiny foliage is almost always a winner even without bloom. P. minor also likes to put out stolens. It is also the most difficult to proprogate from a leaf. I've had leaves down for as long as 6 months before I have even seen a hint of a baby. Patience! Petrocosmea 'Momo' is a baby machine! I am always taking suckers off this plant from under the leaves. I once took 25 suckers out from under the leaves from one plant in a 5" pot. Don't do this! We have since learned that the flowers on P. 'Momo' come from these suckers underneath.

I've been growing P. begonifolia for about four years now. It's an exceptional plant with it's beautiful yellow flowers. The leaves are light green in the center and dark green on the edges. It has crinkled leaves. I have to digress and tell you how I acquired this plant. At the AGGS Convention in Kansas City in 2001, I bid $130.00 for 2 plants no bigger than my thumbnail (we plant people are just a little bit crazy) and lost the bid to Mary Jane Evans. I asked if I could buy a leaf (you can imagine how small they were) and she said no. However, I had written a registration program for the convention that year. Mary Jane's husband was the registration chairman for the next convention and she wanted my program. She offered me a leaf if I would email her husband my program. I jumped at that opportunity! She gave me two leaves and they had four babies. Plant people are wonderful!

Petrocosmea parryorum is another plant with beautifully crinkled leaves that I have now grown for 9 years and have never seen it bloom. I've tried growing it wet, dry, high light, low light, cool, warm, low humidity and in high humidity. However, I have learned that all the suckers that I cut off from underneath the leaves were probably bloom stalks. I said that this was trial and error-more error. P. parryorum and P. kerrii are two varieties that bloom from underneath the leaves. If anyone out there has ever been able to make P. parryorum happy enough to bloom, I'd certainly like to know how you did it.

The largest petrocosmea I have found to date is P. kerrii. It has dark green, long feather shaped leaves. Just beautiful! Then there is P. formosa which is a miniature with dark green, soft, fury leaves and is a medium bloomer.

I have five more which I am now trying to grow, but don't feel at this time that I could give you any valuable or accurate information.

Petrocosmeas are such a delight that I'm sure if you try one, you'll have to have another! and another! and another!

My Petrocosmeas

Petrocosma "Momo" Other Gesneriad