B. Rosie Lerner
Consumer Horticulturist







Question and Answer

Q. I live in northern Indiana. Please tell me how to grow mint. What is the difference between peppermint and spearmint? 

A. Mint is an important commercial crop in Northwest Indiana, with over 9,000 acres raised in 2007 at a value of over $6 million (USDA National Agriculture Statistics Service The bulk of the Indiana mint crop is peppermint, followed by spearmint.

Mint belongs to a botanical genus of plants called Mentha. Peppermint is Mentha piperata; Spearmint is Mentha spicata. These and most other members of Mentha are herbaceous perennials that have similar plant habits. Spearmint is said to be a bit narrower in leaf and flower and a bit more robust in habit than peppermint. However, the key difference among the various types of mint is in the essential oil contained in all parts of the plant. It is this oil that is responsible for the various wonderful flavors. And there are several varieties of both peppermint and spearmint, each with their own distinct variation in flavor. Generally, the greatest concentration of quality oil, and thus flavor, is contained in the foliage, just at the onset of flowering.

Mints are notorious spreaders in the garden and especially prefer moist, but light, well-drained soil. Many gardeners find it helpful to keep mint confined to its own garden beds, confined by root barriers or in raised beds or container gardens to keep the plants in check and because mint requires more moisture than most other garden herbs. Harvest foliage as soon as flowers are noticed and either use fresh or dry or freeze for later use.

While peppermint and spearmint are the most popular, there are many other species and selections, including pineapple, apple and, my personal favorite, chocolate!

See Purdue Extension bulletin HO-28, Growing Herbs in Indiana for additional information on growing and storing herbs.

Q. I have needed to write for some time because I am frustrated with my dogwood tree. It is a "Kousa Dogwood." I've had it for several years. It looks healthy, but it does not bloom -- ever!

A. There are numerous reasons why plants fail to bloom, including immaturity, poor nutrition, insufficient light, pruning at the wrong time of year and spring frosts. Most trees have a juvenile period of growth where flowering will not occur. This is a time when the tree puts the carbohydrates made during photosynthesis to work making a strong root system, more branches and foliage. It can take 5 years or more for many ornamental trees to become mature enough to blossom. Over-fertilizing with nitrogen can delay the onset of maturity -- in other words, promote vegetative growth at the expense of flowering. Kousa dogwood performs best in full sun but will bloom well in light shade. Maturity may be delayed in shady conditions.

Kousa dogwood blooms about 2-3 weeks later in spring than the native flowering dogwood, with blooms appearing at the tips of branches after the leaves emerge. The flower buds are initiated during the late summer and fall of the preceding year. If you prune the tree any time during fall, winter or spring, you will have removed the flower buds for that season. Pruning, if needed, should be delayed until after flowering, and for plants that have not yet reached flowering maturity, pruning in late June should be safe. Severe low temperatures during winter can damage flower buds, but our winters have not been all that severe the last several years. However, spring frost/freezes can damage the flower buds after they've begun to emerge.


Writer: B. Rosie Lerner
Editor: Olivia Maddox,