Does anyone have experience/advice for growing C. guttatum here in z6A Massachusetts? A local rare-plant nursery is listing them this year, nursery-propagated, flowering size, and I'd thought I give them a try if there's any hope in keeping them alive and blooming.

Specifically, recommendations for compost for pot culture? How much light does guttatum require, both in duration and intensity, since they come from so far north? And how cool do they have to be kept during the summer? (I am currently reasonably successful with C. pubescens and C reginae.)

Thanks in advance!

I heard they can be pretty difficult and need at least 5 months of cold winter chill... I'd love to hear other growers' experience with this cyp also!

I have some seedlings that I have grown inside in pot culture. They have done well with daytime temperatures around 70 - 73. I have given them 5 months in the refrigerator. It will be interesting to see their long-term success - they have made it two years so far. Bill Steele keeps them and has many (in northern MN). He cautions about extreme heat sensitivity.

Good luck!

Ron Burch

You will need to really focus on keeping this one cool in the heat of summer. Air temperatures above 80F for extended periods (say days) in particular can send this one into a tail spin. Still, it has been grown as far south as Iowa (zone 5) by Carson Whitlow. I remember reading an article by him about cultivating this species and its near relative C. yatabeanum. He noted that in hot spells plants would get blackening on the leaves and the affected growths would die completely or partially. I also remember him saying that if the plant was well established that it would send out several new growths the following season, but the lion's share would be very small and nonflowering. Here's a guttatum with this leaf blackening (http://www.cypripedium.de/forum/messages/763.html) stress response.

In its native habitat this species rarely sees temperatures above the low 70's and in most cases not above the 60's. That is going to be a problem in your area with summer heat waves. The best solution would be to grow it in a cold greenhouse. Barring that alternative I'd choose a north wall of a house that receives no sunshine, but unobscured light (no tree canopy). I would make a large bed at least a foot deep and several wide (use a sandy soil with lots of pine humus and needles). The bed cannot be in deep shade however since the plants will never flower for you. If you can get them settled in well, then perhaps they will be more heat tolerant the following years.

Let us know how they do!

Thanks for the detailed advice. I was worried about the heat, since we can get weather of 90+ for a week at a time here. Seems like the heat-zone rating for this one is more important than the cold hardiness zone!

I have some reasonable open-shade beds on the N side of the house that stay cooler than the rest of the lot (e.g., the ground is still hard and frozen now!) so while the air temp may get out of bounds, the soil should remain cool. I think Ron's suggestion of indoor culture is the safest, but is probably not for me.

That leaf blackening is certainly vivid...