Commercial Horticulture
  Greenhouse Crops
  Harvest and Postharvest

Long stem roses, the national flower of America, and carnations are two examples of cut-flower crops grown in the greenhouse. Roses are grown in beds on the floor of greenhouses and the plants produce cuttings for about 5 years. The roses receive a full day of natural sunlight, and specialized lightbulbs extend the total amount of light up to 18 hours per day. This way, the plants can be cut four times a year and harvests are timed for Christmas, Valentine’s Day, Easter, and Mother’s Day.

Flowering potted plants include poinsettias, marketed around the winter holidays, and geraniums that are very popular from Mother’s Day through Memorial Day. Poinsettias may have their photoperiod manipulated by bursts of infrared light in order to time the bloom for the holidays. Green plants—which are sometimes called foliage plants or houseplants and include philodendrons, ficus, and ferns—are also grown for sale in pots or hanging baskets.

Bedding plants are often grown in
Figure 6.3 Bedding plants are often grown in
greenhouses, such as at the Plantorium in
LaPorte, Colorado, pictured above.
Bedding plants are raised for sale to consumers who plant them in their gardens or window boxes and include about 50 different types of flowers and vegetables (Figure 6.3). These crops are started in plastic trays called plugs, which are mechanically watered and fertilized. The seedlings are transferred into the flats, small containers, or small pots that are found at the garden center.