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A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Thursday - October 01, 2009

From: Thornwood, NY
Region: Northeast
Topic: Container Gardens, Pruning, Seasonal Tasks, Herbs/Forbs
Title: Overwintering Cardinal Flower in Thornwood NY
Answered by: Barbara Medford

QUESTION:

I have 6 Cardinal Flower plants in planters. They have mulch on top to keep them moist. Can they stay in the planters all winter? Do I cut the stalks before winter comes or leave as is?

ANSWER:

Lobelia cardinalis (cardinalflower) is native to New York and to Westchester County, on the southeastern tip of New York. It is hardy from USDA Hardiness Zones 3 to 10; you are in Zone 6a, with minimum average annual temperatures of  -10 to -5 deg. F, so it would seem the answer to your question is yes. The only reservation we have is that the roots will be in planters instead of the earth. When roots are in the ground, the whole earth is insulating them from the cold. In a planter, they are insulated by the mulch on top of the soil, a few inches of potting soil, and whatever the planter is made of. If it is possible, it would be better if the containers were situated in front of a sunny wall, where the day's warmth from the sun would be re-radiated back out to the nearby plants. If that is not possible, we still think the roots of this plant will be all right, just do everything you can to protect them from freezing temperatures. 

 

From the Image Gallery


Cardinal flower
Lobelia cardinalis

Cardinal flower
Lobelia cardinalis

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