I have heard different opinions on how to treat iris foliage. Some say to cut it down after flowering, and others say to leave it. Which is correct?

Unlike most spring bulbs, bearded iris don’t require a period of cold to produce blossoms. They are also extremely drought tolerant – good for areas with little or no summer rains. Bearded irises are not actually bulbs, but rhizomes – a kind of thick brown root. The rhizomes need plenty of sun to bloom well and regularly. They do best in well-drained soil. To plant a rhizome, dig a large hole, fill the center with a mound of soil and set it on top. If planting in the fall when dormant, cut back existing roots to about three inches. Iris planted in the spring should have their roots fanned out around the sides of the mound. The rhizome itself should sit at about ground level. Growers differ as to whether it is best to cover the rhizome completely with a light layer of soil or to leave the tops a bit exposed.

Irises multiply out from the center, which gradually becomes dry and dead. Every three to four years, they need to be dug up, divided into new plants and replanted to provide the most flowers. Cut off dead blossoms and dead bloom stalks when the iris has stopped flowering, but don’t cut back the leaves until they begin to turn brown in the fall. The leaves are needed to produce next year’s blooms.

A common problem is the iris borer, one of the most destructive insect iris pests. Females lay their eggs on old iris leaves and other plant material in the fall. These eggs spend the winter on leaves and hatch in April or May. Cutting iris leaves back to a four-inch fan and removing other garden refuse during the fall can save iris plants from serious damage next season. Feed your irises a teaspoon of bone meal every fall and when you replant. You can feed again a month before they bloom if you like, but they are quite tolerant of just one feeding.

When can I plant cannas and dahlias out in the garden?

Since neither cannas nor dahlias are the least bit cold-hardy, planting outdoors for both of these beauties should be postponed until all danger of frost has passed. In order to get a head start on the growing season, you could start the canna’s rhizomes and the dahlia’s tuberous roots in containers that have a growing medium of one part potting soil, one part peat moss, and one part builder’s or horticultural sand. When it is safe to start planting your annuals (in southeastern Michigan that should be right around mid-May), then it will be safe to put your cannas and dahlias in the ground.

What does “heirloom” vegetable mean?

There are many opinions on what is an heirloom vegetable. The most common definition: open-pollinated plants (pollination by wind or insects) which are at least 50 years old, and which have been grown continuously. This would include varieties recently reintroduced by seed companies, but which were previously unavailable through the seed trade. Instead, they were preserved over the years by families, or by ethnic, religious, or tribal groups who handed down the seeds from generation to generation. But it also includes varieties that were commercially available in the 19th and early part of the 20th century. The variety must have a history of its own.

This is a broad definition to many. There are those who consider a variety that was available or is now available commercially not to be a true heirloom. Others dislike the “grown continuously” label because it excludes those that were lost and rediscovered. A good example of a lost variety is the Anasazi bean uncovered by archeologists. It had not been grown for 400 years.

Left out are the “modern heirlooms.” These are the new open-pollinated varieties that are the product of accidental natural crossing or intentional cross-breeding. These natural hybrids have the ability to breed true to type. Many of these will be passed on and fifty years from now will earn the title “an heirloom variety.”