Question
Hi
I'm an Illinois Institute of Technology architecture student currently working on a project that attempts to bring portions of a public park indoors in winter time. The project I am presenting tries to incorporate very sustainable features with solar radiation indoors, natural humidity control from solar radiation, and geothermal heating. I was wondering what species of plants might be best for an indoor greenhouse like structure in Illinois. The geothermal system can keep soil temperatures consistently in the 55 to 65 degree range. Although the winter sun gets as low as about 30 degrees for solar noon on the winter solstice, I'm trying to optimize solar penetration for indoor plantlife and for certain hours of the evening in winter there will be indoor lighting which could help sustain plant growth and life. Currently I don't know the exact HVAC systems or humidity controls will be used, but the plants you suggest might help inform what type of system I need to select. Part of the research I did was on the indoor propogation of citrus plants, as done in Paris for hundreds of years now. I've also found Orchids and Gardenias that may be suitable for our conditions. If you have any advice or can suggest proper species of plants I should look into I'd be very appreciative.

Answer
Hi  Dan,

The key factors in selecting appropriate plants for your greenhouse are temperature range and available light.

For the temperature range you have cited, only tropical and semi-tropical plants will survive. Temperate plants from the Illinois area, for example, will not do well in that temperature range.

Some tropical plants require direct sun all day long. At the other extreme, some tropical plants that grow under the forest canopy in deep shade, must be protected from direct sunlight at all times. Many other plants fall somewhere in between these extremes.

There are some species that require high humidity, but generally humidity is not a major determinant in plant selection.

Assuming you have selected plants appropriate to the light and temperature, you then have to know the specifics of each species related to soil composition and proper watering and nutrient management. In other words, you will need an experienced professional to care for the plants and that person should be consulted as to the selection of particular species.

I realize that I have not given you the list of specific plants that were seeking. But without knowing about the light available and the knowledge of those in charge of the plant care, I cannot honestly make specific recommendation to you.

Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC