All plants need carbon dioxide to complete photosynthesis. Mammals take in oxygen and breath out CO2. It is the exact opposite for plants. The stomata on the plants act as lungs for the CO2 to enter the plant. The plant then puts out oxygen into the air. Since plants need CO2 and they are putting out oxygen, extra CO2 in the air will hope the plant grow.
Poinsettias are short day plants and consequently are triggered to bloom by decreasing hours of daylight. Poinsettia growers follow a careful schedule of decreasing light in order to get them to bloom for Christmas. Most poinsettia growers use only artificial light so that light outside the greenhouse won't interrupt the flowering.
Like most hardware stores, Home Depot's stock of plants each year depends largely on what is available from their growers. So, they may carry Hamelia patens one year, but not the next. Your best bet is to call greenhouse growers in your area to see if they plan to stock these. If they don't, many sites like Amazon do, but you will need to start them from seed, though.
Farmers' cooperatives were common among fruit growers in the west.
Sunsweet Growers was created in 1917.
Bradenton Growers was created in 1919.
Bradenton Growers ended in 1926.
Stemilt Growers was created in 1964.
Dakota Growers was created in 1990.
The population of Stemilt Growers is 1,500.
United Grain Growers was created in 1906.
United Grain Growers ended in 2001.
Florida's Natural Growers was created in 1933.