Annual Gardens


The Amien and Florence Carter Trial Garden is a formally designed garden that covers 2 acres. Here we grow and evaluate hundreds of new varieties each year including annuals, perennials, and vegetables. These trials decide what home gardeners find at local nurseries, and seed catalogs, as wholesalers and retailers use them to select cultivars based on how well the plants perform in different areas of the country. Michigan is 3rd in U.S. production of bedding plants and this trial garden helps to promote the horticulture industry.

Peak season for this area is mid-July through mid-September.

Our goals are:

  • To determine how these plants perform in our mid-Michigan growing conditions
  • Inspire the gardening public to explore new varieties and plant combinations
  • To educate the horticulture industry and our garden visitors about our findings and recommendations.


Each year, between 20,000 and 30,000 individual plants, representing approximately 500 different plant varieties, are planted in the annual garden. The vast majority of these 500 varieties are unique from one year to the next; very few are repeated. With such a huge volume and diversity of plant material, precise record keeping is necessary to keep track of all of the plants from the day they are sown in the greenhouse until the day they are planted outside.

Plant breeders generally submit their list of upcoming trial entries to our program during the winter. The breeders supply us with the variety names, as well as their desired growing conditions (e.g. sun vs shade) and planting location (in the ground or in a hanging basket or planter). Depending on the plant variety and starting material (e.g. seeds, cuttings, or vegetatively propagated young plants), the breeders ship us their material at the appropriate time during late winter and early spring to grow in our greenhouses. Some of the plants in the trials are started as early as January, while others are started just weeks before they are planted outside. The various types of starting material are all transplanted into flats, with the exception of some of the larger perennial varieties, which are grown in pots. The plant material is grown in climate-controlled greenhouses with artificial supplementary lighting, and irrigated with a water-fertilizer solution.

Once the weather has warmed and stabilized (generally in late-May), the plants are planted in their final locations in the garden. A bulb planting auger fitted into a cordless drill is used to efficiently dig the approximately 30,000 holes needed. Planting the entire annual garden takes several weeks due to the volume of plant material. Weeding, watering, and fertilizing are all done by hand in order to more closely mimic the growing conditions in a consumer’s backyard garden. The Trial Garden and other displays in the Annual Garden are planted and maintained by the Annual Trial Garden Manager, with the help of student interns and volunteers.